posted March 31st, 2010; last edited March 31st, 2010 –– David Sibley

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  • Books 

    The Sibley Guides series began with the publication of The Sibley Guide to Birds in 2000, and since then has expanded to include four additional books on birds…

    • Sibley Backyard Birding Flashcards 

      Sibley Backyard Birding Flashcards: 100 Common Birds of Eastern and Western North America View at Amazon.com Information from Crown Publishing More…

    • The Sibley Guide to Trees 

      Information from the publisher, Alfred A. Knopf, Inc. Information and sales at your local Independent bookstore or Amazon.com ------------------------------…

      • Press about the Guide to Trees 

        7 Jan 2010 - a short interview with the Boston Globe is here 23 November 2009 - A thirty minute audio interview with Mark Lynch for the show Inquiry on…

    • The Sibley eGuide to Birds App 

      The Sibley Guide to Birds – the most popular, most comprehensive, and fastest-selling printed field guide to North American birds – is now available in…

      • Sibley eGuide FAQ 

        What makes this app different from other bird ID apps? A few key points that set this guide apart from other bird ID apps: Illustrated with paintings…

    • Bright Wings 

      Published Nov 2009 by Columbia University Press Info and sales at Amazon.com or your local independent bookstore An anthology of bird poetry selected…

    • The Sibley Guide to Birds 

      Information from Alfred A. Knopf, Inc (publisher) Info and sales at your local independent bookstore or Amazon.com Publishing history: First…

    • The Sibley Guide to Bird Life & Behavior 

      info from the publisher Alfred A. Knopf, Inc. Info and sales at your local independent bookstore or Amazon.com Published 2001, new cover in Sep…

    • The Sibley Field Guide to Birds of Eastern North America 

      Information from the publisher Alfred A. Knopf, Inc. Info and sales at your local independent bookstore or Amazon.com Originally published in 2003 A…

    • The Sibley Field Guide to Birds of Western North America 

      Published 2003 by Alfred A. Knopf, Inc. Info and sales at your local independent bookstore or Amazon.com Originally published in 2003 Updates and…

    • Sibley’s Birding Basics 

      Information from the publisher Alfred A. Knopf, Inc. Info and sales at Amazon.com or your local independent bookstore Spanish language edition…

    • Hawks in Flight 

      Published by Houghton Mifflin Co. Info and sales at Amazon.com or your local independent bookstore First printing 1988 New cover on paperback…

    • The Wind Masters 

      Originally published by Houghton Mifflin Co. Info and sales at your local independent bookstore or Amazon.com First printing 1993, New cover…

    • The Birds of Cape May 

      Published by Cape May Bird Observatory Publishing history: First edition published in 1993 Completely revised, expanded, and updated edition…

    • Arctic Wings: Birds of the Arctic National Wildlife Refuge 

      Information from the publisher: Mountaineers Books - 200 color photos from award-winning nature photographers Subhankar Banerjee, Michio Hoshino, Steven…

    • Arctic National Wildlife Refuge - Seasons of Life and Land 

      Showcasing the photographs of Subhankar Bannerjee, with essays by David Sibley, Peter Matthiessen, Debbie Miller, George Schaller, Terry Tempest Williams, and…

    • Birds of Denali 

      "An overview of 44 bird species in Denali National Park covering habitat and location, migration stories, and conservation status. Written by Alaska Bird…

  • Shop 

    Below you will find a list of products featuring the work of David Sibley. Click on "details" for more info about any item. Most can be purchased at your…

    • Snowy Owl - limited edition print 

      Price: When you click the "add to cart" button your order info will appear at the bottom of this page. This 9 X 11" limited edition giclee…

    • Payment received 

      Thank you for your payment. Your transaction has been completed, and a receipt for your purchase has been emailed to you. You may log into your account at…

  • Bird Info 

    Bird Information In-depth discussions of identification of North American birds click on any links below to find more info on that topic or species Referen…

    • Families 

      Families of North American birds

    • Species 

      Links to species of all North American birds

      • Barrow's Goldeneye 

        Barrow's Goldeneye  Bucephala islandica Family Anatidae. A diving duck found in small groups on sheltered bays and lakes. Very closely related to Common…

      • Common Goldeneye 

        Common Goldeneye Bucephala clangula Name: ... Main image Family Anatidae Sub-pages Related info item topic Status in North America T…

      • Gadwall 

        Gadwall Anas strepera Name: ... Main image Family Anatidae Related info item topic Status in North America Text. MAP Identific…

      • American Black Duck 

        American Black Duck Anas rubripes Name: ... Family Anatidae Related info item topic Main image Status in North America Throu…

      • American Wigeon 

        Mallard Anas Name: ... Main image Related info item topic Status in North America Text. MAP Identification Very rarely tips up.…

      • Eurasian Wigeon 

        Eurasian Wigeon Anas penelope Family Anatidae Sub-pages Related info item topic Main image Status in North America Rare visitor…

      • Northern Shoveler 

        Northern Shoveler Anas clyptea Name: ... Main image Family Anatidae Sub-pages Related info item topic Status in North America Text. …

      • Chinese Pond-Heron 

        Chinese Pond-Heron Ardeola bacchus Name: ... Main image Family Ardeidae link Status Uncommon to locally common in Asia. Very rare visitor to…

      • Mallard 

        Mallard Anas platyrhynchos Name: ... Sub-pages Related info item topic Main image Status in North America Common and widespread…

        • Mallard monthly variation 

          Sexual, age, and seasonal variation Adult male (> one year old) has green head, white neck ring, gray body, black tail coverts, clear yellow bill,…

        • 'Mexican' Mallard 

          Mallard (Mexican) Anas platyrhynchos diazi Name: ... Family Anatidae link Status Uncommon Related info item topic Main image …

      • Mottled Duck 

        Mottled Duck Anas fulvigula Closely related to Mallard especially to the subspecies 'Mexican' Mallard, with those forms and American Black Duck forming a…

      • Gyrfalcon 

        ==Identification== ===Gyrfalcon vs Northern Goshawk=== Size and shape can be confusingly similar, although to an experienced hawkwatcher in familiar…

    • Hybrids 

      Listing of hybrids of all North American birds in alphabetical order

    • Bird Glossary 

      Glossary of birding terms

    • The Basics of Identifying Bird Sounds 

      Learning bird songs is one of the most important, and most challenging, skills for a birder to develop. There is some level of innate skill and hearing…

      • Learning to Listen to Bird Songs 

        To learn bird songs, it is first important just to notice bird sounds. Train yourself to hear them and to hear the differences. Take a minute periodically…

      • Pitch, and bird song identification 

        Back to the Table of contents Pitch is simply our perception of the frequency (or wavelength) of a sound, which we describe as high to low. Birds’…

      • Tempo, and bird song identification 

        Back to the Table of contents In this discussion, tempo refers to the overall “pace” of the song, the number of notes or phrases per second. We…

      • Understanding Quality, in bird song identification 

        Back to the Table of contents The two variables discussed so far – pitch and tempo – are both measurable, objective features of bird song. The third…

      • Describing Quality 

        In the recording from the previous page - Blue-winged Warbler and Black-capped Chickadee - we learned that chickadee song is whistled while the warbler song…

      • Trilled Songs of Eastern Birds 

        Back to the Table of Contents The simple trilled songs of species like Chipping Sparrow and Dark-eyed Junco offer some of the most difficult, and most…

    • A seldom heard bird sound 

      Presenting this as a "mystery sound" is a bit of a trick question, since this is not a sound that anyone would ever hear in the wild. I made this recording…

    • Field Identifiable Subspecies of birds – an annotated list 

      Below is a draft list of Field Identifiable subspecies of North American birds. Some discussion of the concept behind the list is here. Any suggestions are…

    • Bird References 

      Here are some of the internet bird references that I find most useful. Obviously there are lots more, and this is just a beginning. Feel free to suggest…

    • French Bird Names 

      Below is a list of all species of birds recorded in North America (including escaped and unconfirmed records) and their French names. The names come from the…

    • Greater White-fronted Goose 

      Greater White-fronted Goose Anser albifrons Geographic variation: Four named subspecies are known from North America, three of which breed, but at least four…

    • Canada Goose 

      Canada Goose  Branta canadensis See also Cackling Goose Identification: Canada vs Cackling Goose Distinguishing Cackling and Canada Goose - A comprehensive…

    • Cackling Goose 

      Cackling Goose  Branta hutchinsii See also Canada Goose Identification: Canada vs Cackling Goose Distinguishing Cackling and Canada Goose - A…

    • Trumpeter Swan 

      Trumpeter Swan   Cygnus buccinator Distinguishing Trumpeter and Tundra Swans "The separation of Trumpeter and Tundra Swans has been a perennial challenge..…

    • Townsend's Shearwater 

      Townsend’s Shearwater Puffinus auricularis Not included in The Sibley Guide to Birds; extremely rare, with a single record in North America Brief details…

    • Leach's Storm-Petrel 

      Leach's Storm-Petrel     Oceanodroma leucorhoa Subspecies White-rumped  O. l. leucorhoa Dark-rumped  O. l. chapmani Variation is complex, the…

    • Great Blue Heron 

      Great Blue Heron   Ardea herodias Subspecies: The distinctive population in the Florida Keys, formerly considered a separate species–Great White Heron–…

    • Little Egret 

      Little Egret Egretta garzetta Status Common in Eurasia; a very rare visitor to eastern North America with about 15 records along the…

    • Little Blue Heron 

      Little Blue Heron Egretta caerulea Distinguishing immature (white) Little Blue Heron from Snowy Egret These are the only regularly occurring herons that…

    • American Flamingo 

      American Flamingo   Phoenicopterus ruber The origin of flamingos that appear in the US is discussed in a blog past and comments here: Wandering Flamingos

    • Barrow’s Goldeneye 

      Barrow's Goldeneye  Bucephala islandica Distinguishing female Barrow's and Common Goldeneyes - an overview of the identification challenges of this…

    • Red-footed Falcon 

      Red-footed Falcon  Falco vespertinus Not included in The Sibley Guide to Birds, extremely rare visitor (one record) from Eurasia Details of the identificat…

    • Ruffed Grouse 

      Ruffed Grouse  Bonasa umbellus Variation in Ruffed Grouse tail patterns "...a Ruffed Grouse with a solid tail band is almost certainly a male; one with a…

    • Wild Turkey 

      Wild Turkey Meleagris gallopavo Variation in Wild Turkey

    • Sungrebe 

      Sungrebe Heliornis fulica Not included in The Sibley Guide to Birds; extremely rare visitor from Mexico, one record in the US Also known as American…

    • Spoon-billed Sandpiper 

      Spoon-billed Sandpiper  Eurhynorhynchus pygmeus This species has always been a favorite, with its unique bill shape and an air of mystery – a rare…

    • South Polar Skua 

      South Polar Skua  Catharacta maccormicki Distinguishing South Polar Skua and Pomarine Jaeger

    • Ring-billed Gull 

      Ring-billed Gull  Larus delawarensis A post about the under-appreciated variation in immature Ring-billed Gulls

    • Lesser Black-backed Gull 

      Subspecies Photos of a distinctly dark-mantled adult Lesser Black-backed Gull, South Monomoy Island, MA, 18 Sep 2010. This bird appeared consistently darker…

    • Sandwich Tern 

      Sandwich Tern Thalasseus sandvicensis Sandwich Tern – bill color of juveniles Sandwich Tern – leg color

    • White-winged Tern 

      White-winged Tern   Chlidonias leucoptera Black Tern and White-winged Tern – leg color

    • Green-breasted Mango 

      Green-breasted Mango Anthracothorax prevostii Not included in The Sibley Guide to Birds; extremely rare visitor from Mexico, but increasing recently The…

    • Vaux's Swift 

      Vaux's Swift     Chaetura vauxi A small, dark gray swift, essentially the western counterpart of Chimney Swift. Identification summary: Distinguished…

    • Ivory-billed Woodpecker 

      Ivory-billed Woodpecker Campephilus principalis Not included in the Sibley Guide to Birds (extremely rare, presumed extinct).Download a page on identificat…

    • Olive-sided Flycatcher 

      Olive-sided Flycatcher Contopus borealis Updates and corrections: A misleading presentation in the Sibley Guides leads some observers to the conclusion that…

    • Eastern Wood-Pewee 

      Eastern Wood-Pewee Contopus virens Identification challenge: Eastern vs. Western Wood Pewee These two species are so closely-related and so similar that they…

    • White-crested Elaenia 

      White-crested Elaenia Elaenia albiceps Not included in the Sibley Guide to Birds; extremely rare visitor from South America White-crested Elaenia – new…

    • Cliff Swallow 

      Cliff Swallow Petrochelidon pyrrhonota Mexican Cliff Swallow - A little-known subspecies of Cliff Swallow in Mexico and Arizona appears to be very distinctive,…

    • Cave Swallow 

      Cave Swallow Petrochelidon fulva Geographic Variation Two subspecies groups of Cave Swallow occur in the United States: Mexican Cave Swallow    …

    • Island Scrub Jay 

      Island Scrub-Jay Aphelocoma insularis Taxonomy: The Island Scrub-Jay was considered a subspecies of the widespread Scrub Jay until 1995, when Scrub Jay was…

    • Black-capped Chickadee 

      Black-capped Chickadee Poecile atricapillus Similar Species Carolina Chickadee See Black-capped vs. Carolina Chickadee By far the biggest challenge to…

    • Chestnut-backed Chickadee 

      Chestnut-backed Chickadee Poecile rufescens Geographic Variation Northern Chestnut-backed Chickadee – Poecile rufescens rufescens California Chestnut-bac…

    • Tufted Titmouse 

      No description found for this item.

    • Bicknell's Thrush 

      Bicknell's Thrush Catharus bicknelli Bicknell’s Thrush was long-considered a subspecies of Gray-cheeked Thrush, but when the AOU split Gray-cheeked Thrush…

    • American Robin 

      American Robin Turdus migratorius Subspecies Differences are so slight and variable that no subspecies are reliably identifiable outside of their normal…

    • Curve-billed Thrasher 

      Curve-billed Thrasher Toxostoma curvirostre Geographic Variation Arizona (Sonoran, or Western) - T. c. palmeri group ((includes subspecies palmeri,…

    • Bendire's Thrasher 

      Bendire's Thrasher Toxostoma bendirei Similar Species: Curve-billed Thrasher --- all year, see below Sage Thrasher --- mostly late summer, see below Cris…

    • Tropical Parula 

      Tropical Parula  Parula pitiayumi The apparent hybridization of Tropical and Northern parulas in Texas, and the possibility of a correction to the illustratio…

    • Savannah Sparrow 

      Savannah Sparrow Passerculus sandvicensis Subspecies Corrections and updates to the Guide: In WA all birds are in between reddish and grayish types shown…

    • White-throated Sparrow 

      White-throated Sparrow Zonotrichia albicollis Geographic Variation None Color Morphs White-throated Sparrow occurs in two distinct morphs commonly…

    • White-crowned Sparrow 

      White-crowned Sparrow Zonotrichia leucophrys Geographic Variation Five subspecies, four illustrated in the Sibley Guide: Eastern Taiga…

    • Baltimore Oriole 

      No description found for this item.

      • Mystery Sound - answer 

        23 Jun 2011 – Concord, MA If you'd like to take the quiz before you read the answer, my initial post about the mystery sound is here. You can listen to the…

    • Purple Finch 

      Purple Finch Carpodacus purpureus

    • Pine Siskin 

      Pine Siskin  Carduelis pinus Vocal copying by Pine Siskins

    • Redpolls – main page 

      Common Redpoll  Carduelis flammea Hoary Redpoll  Carduelis exilipes Redpoll Identification notes Distinguishing Common and Hoary Redpolls is extremely…

    • House Sparrow 

      House Sparrow Passer domesticus House Sparrow – "New" for North America?

  • Tree Info 

    In-depth discussions of identification of North American trees click on any links below to find more info on that topic or species Introductory topics An…

    • Useful Online Tree References 

      A list of my most-frequently-used online tree references Taxonomy Taxonomy for higher-level groups (Classes, Orders and Families) in the guide follows the…

    • Eastern Cottonwood 

      Eastern Cottonwood Populus deltoides Corrections The range map published in the Sibley Guide to Trees was made with an older data set and therefore missed…

  • Events 

    David Sibley's Public Events All events are subject to change. Please confirm locations and times with the local venue. I will do my best to update these…

    • The First Round 

      Four "matchups" are shown below, and below each image are checkboxes where you can pick one of the two species as your favorite. Be sure to click the "Submit"…

    • The First Round - Part 2 

      Four "matchups" are shown below, and below each image are checkboxes where you can pick one of the two species as your favorite. Be sure to click the "Submit"…

    • The Second Round, part 1 

      Two "matchups" are shown below, and below each image are checkboxes where you can pick one of the two species as your favorite. Be sure to click the "Submit"…

    • The Second Round, part 2 

      Two "matchups" are shown below, and below each image are checkboxes where you can pick one of the two species as your favorite. Be sure to click the "Submit"…

    • Final flock of four - West and Midwest 

      The matchup between the West champion and the Midwest champion is shown here, and below the image are checkboxes where you can pick one of the two species as…

    • Final flock of four - East and South 

      The matchup between the East champion and the South champion is shown here, and below the image are checkboxes where you can pick one of the two species as…

    • The National Bird Championship 

      This is the National finals, with Pileated Woodpecker representing the East and Scissor-tailed Flycatcher representing the Midwest. Below the image are…

  • Art Gallery 

    Original art I am currently offering commissioned paintings of the bird of your choice. Click for examples and more info. A selection of my older work…

    • Art Auction 

      About the artwork This is an original painting created with gouache (opaque watercolor) on bristol board. These are archival materials and with proper care…

    • Benefit Auction of Red-tailed Hawk art 

      About the artwork This is an original painting created with acrylic on bristol board. These are archival materials and with proper care the painting should…

    • New Art for Sale 

      Commission a painting of a bird of your choice On this page are examples of recently completed commissioned paintings. I am accepting a very limited number…

    • Prints for sale 

      Color Giclee prints for conservation These are archival quality 9" by 11" prints of some of my recent work, and a portion of the proceeds from the sale of…

    • Payment page 

      To purchase artwork the first step is to contact me to confirm that the piece is available, reserve it, and confirm the price and shipping costs. If you…

    • Original Art for sale 

      The gallery below shows original artwork for sale. This sale includes gouache (opaque watercolor) portraits most of which were done for a weekly newspaper…

  • Conservation 

    Bird Conservation: A summary of the threats facing birds is presented in Causes of Bird Mortality Posts about Birds and Window collisions: One of the…

    • Causes of Bird Mortality 

      This chart and the following text were prepared in 2003. Any updates would be welcome.First, it should be stated that the single most significant threat to…

  • Contact 

    Sign up for my free newsletter! If you are having a problem with your eGuide, please check the FAQ here first to see if you find your answer. If that…

  • Shopping Cart 

    No description found for this item.

  • Site Map 

    Below is a complete list of pages and posts on this site. You can set some view options at the right.


Blog Posts

  • Uncategorized  (50)
    • Tempo, and bird song identification 

      May 8, 2012

      Part 3 of my introduction to learning bird songs is now up (click here). In this discussion, tempo refers to the overall “pace” of the song, the…

    • Learning to Listen to Bird Songs 

      May 3, 2012

      The first post in a new series on identifying birds by sound: To learn bird songs, it is first important just to notice bird sounds. Train yourself to hear…

    • Quiz 32 - Warblers from below 

      May 1, 2012

      This quiz shows warblers as they are so often seen in the field - with just the underside of the body visible. Clues such as tail shape, overall size,…

    • Quiz 27: More Warblers and Color Patterns 

      April 11, 2012

      This week's quizzes are looking at some warblers, in anticipation of the spring migration (which is already in full swing in some parts of the country). With…

    • Quiz 26: Warblers and head patterns 

      April 10, 2012

      This week's quizzes will be looking at some warblers, in anticipation of the spring migration. With thanks, again, to Brian E. Small for providing the…

    • Relative size and proportions 

      July 15, 2011

      When considering impressions of shape and size as in Optical illusions and bird identification or More on illusions of size, one important aspect that I've…

    • Bird names in French 

      June 24, 2011

      I've just posted a complete list of French names for North American birds. This is the first step towards adding French names to the eGuide. Please let me know…

    • Blackberry eGuide updates 

      June 7, 2011

      The Blackberry app has been updated again today: Blackberry Update Version 4.1.0 – 7 Jun 2011 Blackberry-style theme (replaces “90′s DOS style”…

    • Updated List of Identifiable Subspecies 

      April 13, 2011

      I've just updated the list of field identifiable subspecies incorporating several readers' comments, adding notes on several species, and adding an asterisk to…

    • The Proper Use of Playback in Birding  

      April 7, 2011

      A Korean translation of this post is here With the recent surge in the availability of digital audio devices, the use of playback to attract birds into view…

    • Distinguishing Green-winged and Common Teal 

      March 26, 2011

      The Green-winged Teal (known as Common Teal in English-speaking parts of Eurasia) is currently considered a single species by the AOU, but two subspecies are…

    • Identifying scoters by shape 

      February 12, 2011

      I was recently studying and sketching the three species of American scoters in Revere, Massachusetts, and I was struck by the differences in head and body…

    • Can Old World and New World Great Egrets be distinguished by call? 

      January 27, 2011

      Possibly... Like most herons, the calls of Great Egret are always hoarse, unmusical croaks and groans. There are slight variations, however, and listening…

    • Beta testers needed for Blackberry app 

      January 20, 2011

      Update, 26 Jan 2011: We have now filled the beta-tester slots. Thanks for the great response! The Sibley eGuide to Birds (for Blackberry) is ready for…

    • Android eGuide now available! 

      November 11, 2010

      Android eGuide now available! The Sibley eGuide is now available in the Android market. Some info is here. Please let me know of any concerns, questions,…

    • Android eGuide and other updates 

      November 1, 2010

      Work is almost finished (really) on the Android version of the Sibley eGuide to Birds of North America, and we hope to have it available within days. In the…

    • Red Crossbill call types act like species 

      September 2, 2010

      Last month (late Aug 2010) I had the pleasure of spending some time at the Nature Conservancy's Pine Butte Guest Ranch in Montana, where an irruption of Red…

    • New draft range maps for Whip-poor-will 

      August 4, 2010

      Maps updated with comments received as of 11 Aug 2010 In the 51st supplement of the AOU Checklist (July 2010), Whip-poor-will is split into Eastern and…

    • New draft range maps for Winter Wren 

      August 4, 2010

      Maps updated with comments received as of 11 Aug 2010 In the 51st supplement of the AOU Checklist (July 2010), Winter Wren is split into Eastern and…

    • Updates to the Sibley eGuide to Birds of North America 

      June 11, 2010

      The eGuide for iPhone was recently updated with all new high-resolution images which can now be displayed full screen; a cleaner and simpler navigation…

    • Mexican Cliff Swallows 

      May 12, 2010

      A little-known subspecies of Cliff Swallow in Mexico and Arizona appears to be very distinctive, and I offer a tentative guide to identification (and lots…

    • Color Illusion and thrush identification 

      May 11, 2010

      The following photo has been the subject of a discussion on the ID-Frontiers listserve recently. It's a Swainson's Thrush, but is it the first-ever record of a…

    • Updates on Spoon-billed Sandpiper 

      April 21, 2010

      Be sure to sign up at 10,000 Birds for your chance to win an original David Sibley painting of Spoon-billed Sandpiper – and help bird conservation efforts at…

    • Upcoming Events - March 2010 

      March 5, 2010

      I have updated my events page with several public events in the next few weeks, including a live radio show with Ken Gale on Tuesday March 9th at 11 AM on…

    • More video of feeding Spoon-billed Sandpipers 

      February 25, 2010

      Here is another video showing two minutes of footage of foraging Spoon-billed Sandpipers at Pak Thale, Thailand. All three clips included here show the…

    • Identification of Spoon-billed Sandpiper 

      February 23, 2010

      One of the most distinctive birds in the world, the Spoon-billed Sandpiper hardly seems like an identification problem, but to pick one out of a flock of…

    • Bill shape and foraging habits of Spoon-billed Sandpiper 

      February 21, 2010

      The Spoon-billed Sandpiper has one of the most striking and unusual bill shapes of any bird, but the function of the odd spoon-shaped bill has never been…

    • Finding Spoon-billed Sandpipers in Thailand 

      February 20, 2010

      My trip to Thailand (4-14 Feb 2010) was a great success, and I'll be posting some observations, photos, and sketches here over the next few days. The known…

    • Off to chase Spoon-billed Sandpiper 

      February 1, 2010

      I'll be in Thailand for the next two weeks, hoping to fulfill a decades-long dream to see Spoon-billed Sandpiper. Like many birders, I have always been…

    • Distinguishing female Barrow's and Common Goldeneyes 

      January 21, 2010

      minor updates 2 Mar 2010Identifying female goldeneyes is extremely challenging. Differences are subtle, subjective, and inconsistent, but experienced observers…

    • New page on Tree references 

      January 19, 2010

      I've just posted a new page that lists some of my most-frequently-used online references about trees. You can find it here, and it is also linked on the Tree…

    • Identification of (hybrid?) female Goldeneyes 

      January 13, 2010

      Distinguishing Common and Barrow's Goldeneyes is always a challenge, and particularly so when the bird is a female. One of the most conspicuous and easily…

    • Updates 

      January 12, 2010

      I'm back to the website after a long holiday break, and I have a few things I'll be posting over the next two weeks. For now, important news to report is…

    • Updated bird names for The Sibley Guide to Birds 

      October 9, 2009

      This list covers changes (through Nov 2009) to the official names of birds as published by the American Ornithologist’s Union (AOU) in periodic supplements…

    • Sungrebe – New for North America! 

      November 19, 2008

      Stunning news from Bosque del Apache NWR in New Mexico: a female Sungrebe was photographed there on 13 November 2008, those photos here. It was correctly…

    • House Sparrow - "New" for North America? 

      February 19, 2008

      You might think that the words "intriguing" and "House Sparrow sightings" are mutually exclusive, but here's a case where they go together! In October 2007 a…

    • White-crested Elaenia - new for North America 

      February 11, 2008

      From Texas comes the remarkable news of the discovery of an apparent White-crested Elaenia (Elaenia albiceps) found by Dan and Honey Jones on 9 Feb 2008.…

    • What are the odds? 

      December 31, 2007

      Slaty-backed Gull in Gloucester, MA on 23 December 2007 - Photo by Phil Brown Part 1: On 6 December 2007 at about 8PM, in the midst of an intense winter…

    • More rare bird news and a correction 

      November 14, 2007

      The latest Siberian highlight was California's first Eurasian Kestrel banded in Marin Co. CA on 23 October 2007 but not seen again (photos here). About 10…

    • Wandering Flamingos 

      October 13, 2007

      A fascinating story of two flamingos, one from the Yucatan that provides a very rare undisputed US record of a wild bird, and another from the Old World (via a…

    • More Siberian vagrants 

      October 4, 2007

      In my previous post about Siberian birds I made a tenuous connection between an above-average season for vagrants in the Bering Sea and a few vagrants farther…

    • Siberian vagrants on the move? 

      September 22, 2007

      Update 24 Sep 2007: Seen on the 22nd was Gambell's 3rd Siberian Accentor, 4th Dusky Warbler, and 6th Little Bunting of the season; while St Paul, Pribilofs…

    • Rare bird news 

      August 30, 2007

      An eventful few weeks for bird records in North America:The long-anticipated first nesting record of Lesser Black-backed Gull in North America (even though it…

    • Distinguishing Trumpeter and Tundra Swans 

      February 19, 2006

      The separation of Trumpeter and Tundra Swans has been a perennial challenge. Both are obviously swans, and given decent looks they are easy to distinguish from…

    • Updates and Corrections for the Sibley Western Guide 

      November 6, 2004

      p 143 – Pacific Golden-Plover: on adult male breeding the labels pointing to undertail coverts and flanks are reversed. p. 252 – White-throated Swift:…

    • Updates and Corrections to the Sibley Eastern Field Guide 

      November 6, 2004

      p. 76 – Northern Shoveler text in mid-paragraph says “with with” p 136 – Shorebirds family, parentheses at end of paragraph are unclear. This should…

    • Prints for sale 

      November 2, 2004

      Black-and-white prints from “The Wind Masters” Osprey print is sold out. This set of four prints is taken from artwork originally published in The Wind…

    • What species are in the Eastern and Western bird guides? 

      October 27, 2004

      The Eastern and Western Guides were carefully planned to avoid dividing states. The Rocky Mountains form a natural biological and climatic division of the…

    • Which bird book should I buy? 

      October 27, 2004

      The Sibley Guide to Birds Focus: bird identification Region covered: North America north of Mexico Species covered: 810 The Sibley Guide to…

    • Interviews 

      October 27, 2004

      North Country Public Radio - October 10, 2003 David Sibley led a group of North Country birders along Clarkson University’s nature trails last fall. Martha…

  • Bird Identification  (167)
    • Peter Pyle on Sage Sparrows 

      August 20, 2013

      The most significant change for North American birders in the 2013 AOU Checklist supplement is the split of Sage Sparrow into two species: Sagebrush Sparrow…

    • Another odd Snowy Egret, or a hybrid? 

      May 22, 2013

      Recently on Cape Cod, Massachusetts, Mary Keleher noticed an egret with two long head plumes, and took a couple of photos. This bird matches well with the ones…

    • Flycatcher identification by the calendar 

      April 12, 2013

      Here are some eBird maps showing all records for the month of April for several species of small flycatchers in eastern North America. A glance at these maps…

    • Pairs as an aid to hawk identification 

      March 4, 2013

      By the end of February, even in cold and snowy Massachusetts, Red-tailed Hawks are courting and forming pairs in preparation for nesting. It's common to…

    • A video bird quiz 

      February 14, 2013

      The answer is at the end of the video, and in the text below. http://youtu.be/51jRz9crJt4 It has been a relatively mild winter in Massachusetts, but the…

    • Dark heron/egret 

      February 5, 2013

      Can you identify the two birds in this photo? It should be immediately obvious that this photo shows two species of dark herons, and their overall…

    • Quiz 54: Head patterns 

      January 2, 2013

      The three photos below show a Song Sparrow as it turns its head. Your challenge is to locate the plumage marking known as the lateral throat stripe in each…

    • Posture and shape distinguishes male and female Dark-eyed Juncos 

      December 19, 2012

      Backyard Bird Discoveries While watching a small flock of juncos at my bird feeder on December 17, 2012, I noticed one particularly brownish female. Considerin…

    • Can you find the Cackling Goose?  

      November 16, 2012

      One of the biggest challenges of identifying a Cackling Goose is just finding one, especially in the east where the species is rare and occurs mostly as single…

    • My trick to finding Rusty Blackbirds 

      November 5, 2012

      Almost every Rusty Blackbird that I see in the eastern United States is in flight, so the simple trick is to look up. In order to do that you need to know what…

    • Quiz 53: Eastern Sparrows in early September 

      September 12, 2012

      Below are three sparrows photographed in Concord, MA on 11 Sep 2012. Can you identify the species? Today's quiz features a bonus Everyone who submits a…

    • Juvenal plumage of songbirds: Gray Catbird 

      September 8, 2012

      Most Passerines only hold juvenal plumage for a few weeks, quickly molting to a more adult-like plumage soon after they fledge and before fall migration. It's…

    • Quiz 50: Bird topography - upperside 

      September 5, 2012

      Here is a new quiz about the topography of the upperparts of a large songbird.

    • Distinguishing immature (white) Little Blue Heron from Snowy Egret 

      August 18, 2012

      These are the only regularly occurring herons that are truly difficult to identify, as immatures of these two species are variable in bare-parts color and…

    • Identification of Waterthrushes 

      August 17, 2012

      First Glance A quick judgment of the ground color of the breast and eyebrow stripe will separate most waterthrushes: bright white on Louisiana, yellowish…

    • Quiz 48: Mystery Bird 

      August 16, 2012

      This bird was photographed in North America, and it's not some exotic vagrant.

    • Determining the age of white egrets and herons in late summer 

      August 15, 2012

      Identifying the white herons and egrets can be a challenge. We must rely mainly on structure, behavior, and the color of bare parts like bill and legs,…

    • Quiz 45 - Little Brown Bird Identification 

      August 10, 2012

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    • Quiz 44 - Bird flying away 

      August 9, 2012

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    • Why are Yellowlegs hard to identify? 

      July 26, 2012

      The flippant answer is "...because they look alike", and they can be very alike. Most of what you read about yellowlegs will tell you to look at bill…

    • Quiz 43: Still more songbird legs and feet 

      July 26, 2012

      Here are three more songbirds showing some of the variation in legs and feet. With thanks, again, to Brian E. Small for providing the beautiful photos. You…

    • A Yellow Purple Finch in Ontario 

      July 25, 2012

      Thanks to reader Skip Pothier for sending in these photos. They show a Purple Finch with yellow color instead of red. My first thought was to call it a male…

    • Quiz 41: More identification by feet 

      July 20, 2012

      More examples of the variety of legs and feet – color and structure – that can be found among the small songbirds. With thanks, again, to Brian E.…

    • A heron ID quiz 

      July 17, 2012

      Here is a photo of a white heron, taken by Constance Mier on the main shoreline of Biscayne Bay National Park, near Miami, Florida, on May 25, 2012. You…

    • Quiz 39: Bird ID by legs and feet 

      July 16, 2012

      The structure and color of birds' legs is extremely variable. Everyone knows the difference between the webbed foot of a duck and the unwebbed toes of a…

    • More unusual Cattle Egrets 

      May 28, 2012

      After my post a few days ago about the unusual Cattle Egret in Florida, I heard from two people with interesting observations to add. Robert Edgar and…

    • Quiz 37: Bird topography 

      May 23, 2012

      Test your knowledge of bird feather topography with the questions below.

    • An unusual Cattle Egret in Florida  

      May 22, 2012

      In late April 2012, Roy Halpin found and photographed an entirely buff-colored Cattle Egret in Saint Augustine, Florida. This is a particularly interesting…

    • Bird Song ID series continues - Eastern Trills 

      May 18, 2012

      The next part of my introduction to learning bird songs is now up (click here). Birds can hear a lot “faster” than we can, however, and consequentl…

    • Bird songs Part 5: Describing Quality 

      May 14, 2012

      Part 5 of my introduction to learning bird songs is now up (click here). Many of the words that we use to describe the quality of a bird song also…

    • Part 4: Understanding Quality in bird song 

      May 11, 2012

      Part 4 of my introduction to learning bird songs is now up (click here). In the narrowest sense, the quality of a bird’s voice would refer strictly…

    • Quiz 36: More Warblers 

      May 10, 2012

      Today's quiz features a bonus And we have a winner! Congratulations to Laramie, and thanks to everyone who entered! There will be another quiz giveaway…

    • Tempo, and bird song identification 

      May 8, 2012

      Part 3 of my introduction to learning bird songs is now up (click here). In this discussion, tempo refers to the overall “pace” of the song, the…

    • Quiz 35 - More warblers from below 

      May 7, 2012

      Like a previous quiz this one shows warblers as they are so often seen in the field - with just the underside of the body visible. Clues such as tail shape,…

    • Pitch, and bird song identification 

      May 4, 2012

      Pitch is simply our perception of the frequency (or wavelength) of a sound, which we describe as high to low. Birds’ range of hearing is similar to our own,…

    • Quiz 34 - Brightly-colored Birds 

      May 3, 2012

      Here are five species of intensely colorful spring birds. Can you identify them from just the small parts that are visible? Today's quiz features a…

    • Quiz 33: Small songbirds by their wings 

      May 2, 2012

      This quiz shows just the bodies of five species of small drab songbirds with wingbars. In other quizzes I've given a big clue in the form of telling you the…

    • The annual plumage cycle of a male American Goldfinch 

      May 1, 2012

      Molt is the process of feather replacement. All birds do it; they have to grow new feathers once or twice a year to stay warm, dry, and airborne, and in many…

    • Quiz 32 - Warblers from below 

      May 1, 2012

      This quiz shows warblers as they are so often seen in the field - with just the underside of the body visible. Clues such as tail shape, overall size,…

    • Mystery Bird Song - Concord, MA 

      April 29, 2012

      I recorded this sound (with my iPhone, please excuse the poor quality) on 29 April 2012 near my house in Concord, MA. Have a listen and see what you think. For…

    • Quiz 31: More warblers by partial cues 

      April 27, 2012

      Here are some partially obscured warblers to test your knowledge. Look especially at the pattern of wingbars to distinguish these three. With thanks,…

    • In praise of mystery 

      April 26, 2012

      The still-unidentified Elaenia, found by Ethan and Aaron Gyllenhaal in Illinois, has provided one of the most exciting and interesting bird identification…

    • Quiz 30: Comparing bird weights 

      April 24, 2012

      Continuing the challenge of comparing bird weights, here are some familiar species to test your knowledge.

    • Quiz 29: Comparing bird weights 

      April 23, 2012

      Today's quiz revisits the challenge of comparing bird weights. In the field we get a sense of the "bulk" of a bird, and that is a very important part of…

    • Bird Topography - How it helps identify birds 

      April 16, 2012

      I was musing on the value of learning bird topography this morning, wondering why it is so important to know the greater coverts and supercilium and all the…

    • Quiz 28: More Warblers 

      April 13, 2012

      Update: Congratulations to Vjera, the winner of this week's prize drawing! Thanks to all who entered. Watch for another giveaway next week. The quiz prize…

    • Quiz 27: More Warblers and Color Patterns 

      April 11, 2012

      This week's quizzes are looking at some warblers, in anticipation of the spring migration (which is already in full swing in some parts of the country). With…

    • Quiz 26: Warblers and head patterns 

      April 10, 2012

      This week's quizzes will be looking at some warblers, in anticipation of the spring migration. With thanks, again, to Brian E. Small for providing the…

    • Quiz 25: Wing patterns 

      April 6, 2012

      Update: Congratulations to Alvan, the winner of the Backyard Birds poster. Thanks to all who took the quiz and entered. The response was fantastic, and keep…

    • Quiz 24: Wing Patterns 

      April 5, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 23: Wing patterns 

      April 4, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 22: Wing patterns 

      April 3, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 21: Wing patterns 

      April 2, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Announcing my new video guide to bird songs! 

      April 1, 2012

      Update: For future visitors I should explain that I posted this as an April Fool's Joke. This video converts the voice descriptions from the Sibley Guide to…

    • Identification of female bluebirds by wing structure 

      March 27, 2012

      A pale and grayish female bluebird found in North Carolina recently (March 2012) provided a very interesting identification challenge. The plumage colors were…

    • Quiz 20: Wings, long and narrow 

      March 15, 2012

      This quiz groups some relatively long and narrow wings. Pay special attention to subtle differences in shape, and bold white patterns. With thanks to the…

    • Quiz 18: Blue bird parts 

      March 12, 2012

      This quiz shows just parts of three different blue birds. Try to identify the species while seeing only part of the body. With thanks, again, to Brian E.…

    • Off to Belize 

      March 11, 2012

      I'll be away in Belize for the next week or so, leading a trip for Mass Audubon, and in anticipation of that I've posted a photo of one of the most iconic…

    • Quiz 17: Western birds in part 

      March 9, 2012

      Here's a new variation for an ID quiz. Birds in these photos are mostly masked by black. See if you can identify the species without seeing the whole bird. W…

    • Quiz 16: Identifying blue wings 

      March 8, 2012

      Wings are amazing. Marvels of engineering, with intricate and changeable color patterns, they offer endless avenues for study. But seeing the details of a wing…

    • A head feather survey 

      March 7, 2012

      Update: 9 March 2012 Thank you! The response to the head feather survey has been fantastic: 95 participants as of 10 AM on March 9th. The survey will be…

    • What is the submoustachial? 

      March 7, 2012

      The feathers along the side of the lower jaw have a very confusing history of terminology. They've been called the malar stripe (in many early and mid 20th…

    • Quiz 15: The submoustachial 

      March 6, 2012

      Regardless of what you call them – submoustachial, malar, jaw stripe, mandibular stripe – the feathers along the side of the lower jaw are important for…

    • Variation in head pattern 

      March 5, 2012

      In recent posts and quizzes here I've been stressing the head feather groups, and how they provide a consistent structure for understanding the color patterns…

    • The changeable shape of the supercilium 

      March 3, 2012

      The feathers that grow on the sides of the head above the eyes of a bird are called the supercilium, and when they contrast in color with the adjacent feathers…

    • Quiz 12: More on head feathers 

      February 29, 2012

      A teaser of spring wood-warblers on this bonus day of February. Two questions for each of the photos will help you practice applying your knowledge of head…

    • Trumpeter Swans, yellow bill spots, and leucism 

      February 29, 2012

      In a previous post I've talked about Trumpeter Swans with yellow bill spots as a source of  confusion with Tundra Swan. I speculated that the yellow spots…

    • Introduction to breast feathers 

      February 28, 2012

      One of the well-defined groups of feathers on the underside of a bird is what we call the breast. In reality, on songbirds these feathers grow from the…

    • Quiz 11: Head feather groups and simple color patterns 

      February 22, 2012

      This quiz is about taking the feather groups you've learned in previous quizzes, and applying them to real birds, to see how color patterns follow the basic…

    • Quiz 10: Head feathers - without markings 

      February 21, 2012

      This quiz features a Dark-eyed Junco, a species with no discernible color pattern on the head. How can you distinguish groups of head feathers with no color…

    • Quiz 9: More on Head feathers 

      February 20, 2012

      Here is a close-up of the head of a Song Sparrow, showing the feather groups and feather markings really well. In the copy below, I've outlined the feather…

    • Quiz 8: Introduction to head feathers 

      February 16, 2012

      Color patterns on the heads of birds are some of the most complex, and also some of the most important for identification. Understanding those patterns is…

    • Quiz 6: Bird weight 

      February 13, 2012

      Below is a chance to test your knowledge of bird size, by selecting the heavier species in each of five pairs of birds. Weight, or apparent bulk, is one of the…

    • Quiz on Bird Topography: Wings 3 

      February 10, 2012

      Each label in the photo above points to a feather group associated with the wings. In the quiz below, choose the correct name for that labeled feather…

    • Quiz on Bird Topography: Wings 2 

      February 8, 2012

      Identify the two labeled feather groups in the quiz below, with a couple of bonus questions.

    • A quiz on bird wing feathers 

      February 7, 2012

      The major groups of feathers on the wing are showing well on this American Robin, and each is labeled with a letter. In the quiz below, select the letter…

    • Backyard Bird Quiz: part II 

      February 6, 2012

      Here's the next installment in quizzes. I've removed the titles this time so hovering over the image shouldn't give it away (but some browsers will still show…

    • Variation in immature American Herring Gulls 

      February 3, 2012

      A recent discussion about geographic variation in Herring Gulls (on the ID-Frontiers listserve) prompted me to go back and scan some photos I took in 1998 at…

    • New feature: a bird identification quiz 

      February 1, 2012

      Identify the species shown in each photo by clicking the multiple choice answers. I hope to make short quizzes like this a regular feature of this website, so…

    • The two stages of field identification 

      January 30, 2012

      As I work on the revision of my field guide I've been giving a lot of thought to how the book can assist the process of identification, and what information is…

    • A Wurdemann's-like heron from South Florida 

      January 25, 2012

      Thanks to reader Anne DuPont for sending in these photos of a pair of Great Blue Herons at Wakodahatchee Wetlands, Delray Beach, Florida. It's clearly a mated…

    • Identifying sleeping female goldeneyes 

      January 20, 2012

      Like many other species of ducks that are distinguished by head shape, Common and Barrow's Goldeneyes are at least as easy to tell apart when sleeping as when…

    • Distinguishing male and female American Goldfinches 

      January 19, 2012

      For much of the year, distinguishing male and female American Goldfinches is easy (when the males show their brilliant yellow summer plumage, about March…

    • Subspecies of Scaled Quail 

      January 17, 2012

      There are four named subspecies of Scaled Quail, three in the US and one in Mexico. The subspecies found in southern Texas is distinctly different from the…

    • Do "dwarf" birds exist? 

      January 13, 2012

      A recent discussion on the ID-Frontiers listserver involved an immature gull photographed in Utah (photo by Norman Jenson here). The consensus (and I agree) is…

    • Identification of white geese 

      December 7, 2011

      Recent discussion of the identification of a white goose in Ohio (beginning here) prompted me to put together some sketches of bill shapes of Ross's and Snow…

    • Overconfidence 

      October 27, 2011

      A recent article by Tim Enthoven in the New York Times - Don’t Blink! The Hazards of Confidence - offers some fascinating thoughts on judgment, expertise,…

    • On identifying Chipping and Clay-colored Sparrows 

      October 25, 2011

      I recently commented on this ID problem on MassBird, pointing out differences in details around the eyes. Chipping sparrow has very distinct, narrow whitish…

    • Progress on the orange-throated hummingbird mystery 

      August 16, 2011

      Thanks to Sheri Williamson (author of the Peterson Field Guide to Hummingbirds) and her recent post titled Orange-throated hummingbirds - not so mysterious…

    • The finer points of wing translucence  

      August 15, 2011

      Patterns of translucence in wing feathers provide useful identification clues for many species of birds - terns, gulls, hawks, and others. Generally the…

    • Orange-throated Hummingbirds: more questions 

      August 14, 2011

      Now updated by a new post Progress on the Orange-throated hummingbird mystery. This adds to my previous post about orange-throated hummingbirds. After…

    • Abnormal coloration in birds: Melanin reduction  

      August 5, 2011

      Albino and partial albino birds The presence of white feathers on a normally dark bird is the most frequently seen color abnormality. Every birder can…

    • The mystery of the orange-throated hummingbirds  

      August 4, 2011

      Update 16 August: a new post Progress on the orange-throated hummingbird mystery. Update 14 Aug 2011: A follow-up to this post is now available,…

    • Possible hybrid Little x Snowy Egrets 

      August 1, 2011

      A few records of “Snowy” Egrets with long head plumes have turned up in places where Little Egret has also occurred. Are they hybrids, or just rare…

    • Can Short-tailed Shearwater be identified in the field? 

      July 30, 2011

      Usually. Experienced observers can almost always identify these species correctly based on careful judgment of head shape and bill size, but these are subtle…

    • Distinguishing Eurasian and American Common Merganser 

      July 29, 2011

      The Eurasian subspecies group of Common Merganser, known by the English name Goosander, has occurred numerous times in the Aleutian Islands of western Alaska,…

    • Trumpeter Swans with yellow loral spots 

      July 25, 2011

      The photo above was recently sent to me by reader Wil Domke. It shows an adult Trumpeter Swan (based on bill size and shape, and on Wil's identification in…

    • The mysterious dark Least Bittern 

      July 23, 2011

      Dark morph (Cory's) Least Bittern Note: I have never personally seen a living Cory's Least Bittern. In fact, only six or so have been seen during my lifetime.…

    • The Newfoundland Moorhen was an American based on back color 

      July 19, 2011

      Last winter's Common Moorhen in Newfoundland, given the likely split of New World and Old World moorhens into separate species, led me to try to determine the…

    • Differences in plumes of Little and Snowy Egret 

      July 18, 2011

      In these two very similar species, the head plumes of adults provide the single most obvious and reliable distinction. The brief descriptions in field guides…

    • More on illusions of size 

      July 14, 2011

      This is a follow-up to my recent post about Optical illusions and bird identification. While working on some heron studies the other day, I found a good…

    • Does Blackpoll Warbler have song dialects? 

      July 1, 2011

      I've been aware of some variation in songs of Blackpoll Warbler for many years, and now an interesting post by Andrew Spencer at Earbirding prompted me to…

    • Powder down and the Black-crowned Night-Heron  

      June 29, 2011

      In a footnote here I mentioned that blackish feathers can appear gray because of powder down, and now I will offer a little more explanation. Powder…

    • Does Cattle Egret have a dark morph?  

      June 28, 2011

      On 18 May 1987, while birding at Cape May, NJ, I came across a small group of Cattle Egrets foraging in a field. Accompanying them was the bird in the photos…

    • A Mystery Sound 

      June 24, 2011

      23 Jun 2011 – Concord, MA Sitting at my desk today I was roused by a bird call that I did not immediately recognize. This is a very rare occurrence for me,…

    • An apparent hybrid Yellow-billed x Common Loon  

      June 22, 2011

      On 9 Jun 1987 I was leading a WINGS tour group at Churchill, Manitoba, and we chartered a small boat to go out on the river for an hour or so to see Belugas…

    • Optical illusions and bird identification 

      June 20, 2011

      Here is a classic optical illusion - the three horizontal lines in the image below are all the same length. Yes, they are identical (move your cursor over the…

    • Distinguishing Interior West from Western Taiga White-crowned Sparrows 

      May 20, 2011

      See my detailed discussion of White-crowned subspecies here, which needs updating with the information below. In early May 2011 I spent several days in…

    • A "mystery" oriole and the limitations of identification by impression 

      May 19, 2011

      On 9 May 2011 several birders saw and heard a strange oriole in Georgetown, South Carolina (photos here). They identified it as a Scott's Oriole, a first state…

    • Intergradation between Mexican Duck and Mallard in Arizona 

      May 6, 2011

      The Mexican Duck was formerly considered a species (Anas diazi), and is currently lumped with Mallard (as subspecies Anas platyrhynchos diazi), but recent DNA…

    • Three interesting Brant from Massachusetts 

      April 12, 2011

      Note: I'm preparing posts on the range and identification of Brant subspecies, which will help make the following more understandable to those who are not…

    • Identifying subspecies by behavior - Savannah Sparrow 

      March 28, 2011

      Identifying subspecies adds richness to your birding by adding another layer of understanding. What’s more, during spring migration, behavior can offer a…

    • Distinguishing Green-winged and Common Teal 

      March 26, 2011

      The Green-winged Teal (known as Common Teal in English-speaking parts of Eurasia) is currently considered a single species by the AOU, but two subspecies are…

    • Distinguishing the subspecies of Purple Finch  

      March 22, 2011

      Summary The two subspecies of Purple Finch are fairly distinctive with well-defined ranges. They are best distinguished by overall impression of…

    • Can subspecies of Mountain Chickadee be identified in the field?  

      March 22, 2011

      Not really. Only under ideal conditions and with reference to location. Mountain Chickadee is found throughout much of the montane coniferous forest…

    • Identifying songbirds by flocking behavior  

      March 16, 2011

      It's early morning and you're out on a bird walk following your guide under a gray sky. A flock of small songbirds flits over the distant treetops. The…

    • The 'Caribbean' Coot in North America 

      March 15, 2011

      Caribbean Coot Fulica caribaea (found sparingly and locally in the West Indies from Hispaniola south and east to the coast of Venezuela) is virtually…

    • Another clue for identifying Downy and Hairy Woodpeckers 

      March 14, 2011

      In a previous post I wrote about differences in the black-and-white pattern on the neck of Downy and Hairy Woodpeckers, and in comments there Dan Lane reminded…

    • Identifying small songbirds by flight style  

      March 11, 2011

      It's easy. Experienced birders do it subconsciously, using clues from the wingbeats, rhythm, and path of a bird's flight. These are usually described in vague…

    • Identifying Downy and Hairy Woodpeckers by drumming sounds 

      March 3, 2011

      Instead of song, most woodpeckers use a mechanical drumming sound as their audio advertising display. It's easy to tell when you hear a woodpecker, harder to…

    • Sparrows and central spots 

      February 25, 2011

      Can you identify the sparrow shown in this photo? Read on for the discussion and answer below. Thanks to Jerry Tang for the photo and for bringing it to my…

    • Four redpoll taxa in one photo  

      February 22, 2011

      Michael Butler of Marathon, Ontario sent me the remarkable photo below, showing all four taxa of redpolls (four subspecies, two species) in one view (see more…

    • Can Eurasian Common Moorhen be identified by sight? 

      February 17, 2011

      Maybe, it depends how sure you want to be. Update July 2011 - See my new post on Back color of Moorhens for an additional clue to identification …

    • A new clue for identifying Downy and Hairy Woodpeckers 

      February 16, 2011

      A few years ago I was alerted to a subtle difference in the head patterns of Downy and Hairy Woodpeckers when I read a short note by Mark Szantyr with a nod…

    • Identifying scoters by shape 

      February 12, 2011

      I was recently studying and sketching the three species of American scoters in Revere, Massachusetts, and I was struck by the differences in head and body…

    • Identifying Chimney and Vaux's Swifts by wing shape 

      October 11, 2010

      For most observers the identification of these two species is simple, and is based entirely on location, with Vaux's in the west and Chimney in the east. It is…

    • You too can record and identify Crossbill call types 

      October 5, 2010

      If you've followed any of the discussions about identifying Red Crossbill call types, you may have given up on taking an active role in crossbill study,…

    • Variation in immature Ring-billed Gulls 

      December 1, 2009

      On October 9th, 2005 I was enjoying the view at First Encounter Beach in Eastham, Massachusetts and watching a small flight of seabirds. A flock of gulls began…

    • Variation in Ruffed Grouse tail patterns 

      November 12, 2009

      Since The Sibley Guide to Birds was published in 2000 I've received several comments and questions about the fact that I illustrated the displaying male…

    • Ageing Canada Geese 

      October 20, 2009

      Determining the age of a goose can be helpful for identification, and can also reveal some interesting behavioral and ecological information by enabling you to…

    • Probability in bird identification 

      October 1, 2009

      One of my regular birding spots is a small farm field near my house in Concord, Massachusetts. I can walk around the entire place in about 20 minutes, but I…

    • More vocal copying by American Goldfinch, Purple Finch, and Ovenbird 

      July 9, 2009

      After listening carefully to Pine Siskins this year to pick out the calls of other species (see my earlier post) I have run across several other mimics. In…

    • Identification of Belding's Savannah Sparrow 

      May 14, 2009

      In early March 2009 it was my pleasure to spend a few days in California at the San Diego Bird Festival. On my first morning in San Diego I headed straight out…

    • Vocal copying by Pine Siskins 

      May 13, 2009

      In July 1990 I spent several weeks birding in west-central British Columbia, where Pine Siskins were one of the most conspicuous birds, and I became convinced…

    • More on identification of Greenland White-fronts 

      November 24, 2008

      Coincidentally, just days after my last post about the two White-fronted Geese in Concord, two White-fronted Geese showed up in Amherst, Massachusetts (about…

    • Identification tips for Greenland Greater White-fronted Goose 

      November 21, 2008

      The Greenland Greater White-fronted Goose (Anser frontalis flavirostris) is known to be a rare visitor to northeastern North America, but I have never been…

    • Lesser Canada Goose in the northeastern US 

      November 17, 2008

      The primary challenge of distinguishing Canada from Cackling Goose centers on the intermediate-sized 'Lesser' Canada Goose, B. c. parvipes, which reportedly…

    • So how many do we find? 

      November 6, 2008

      My last post "How many rare birds do we miss?", was simply getting at the idea that we can miss something glaringly obvious if we are not looking for it. A…

    • Variation in Wild Turkey 

      April 2, 2008

      Here's an example of one of the countless thousands of questions that are still out there waiting to be answered about North American birds. I went to Texas in…

    • Audubon's mysteries: Carbonated Swamp-Warbler 

      March 28, 2008

      One of the enduring mysteries of North American ornithology involves several species which were painted by Audubon in the early 1800s but never seen again. The…

    • Greater Redpoll photos 

      March 11, 2008

      Maybe I should change the name of this blog to "All about Redpolls", but I've received a few photos that I wanted to pass along, making the point that…

    • Another large pale redpoll 

      March 10, 2008

      A new photo by Dan Berard shows what looks like an intermediate large redpoll, and should be added to the discussion in my previous post.photo copyright Dan…

    • Redpoll investigation widens to include "Greater" 

      March 7, 2008

      Maybe we are just more aware and looking harder for "Greater" Common Redpolls (Carduelis flammea rostrata) this winter in Massachusetts, or maybe it's really…

    • Where do Hoary Redpolls winter? 

      March 3, 2008

      In considering the true status and distribution of Hoary Redpoll, I realized that I had overlooked one significant source of information - the Christmas Bird…

    • Redpoll age variation and ID 

      February 13, 2008

      The question of age variation has come up repeatedly in redpoll discussions, so I finally tried to find an answer to the question of just how important…

    • Urging caution when identifying Common Redpolls 

      January 14, 2008

      Redpoll identification is challenging because Hoary and Common Redpoll seem to show an unbroken continuum of variation from pale to dark, and there are no…

    • Comments on two redpolls 

      January 8, 2008

      I'm reposting here some comments I just sent to ID-Frontiers, about a pale redpoll in Illinois and another in Massachusetts:The comment under these photos on…

    • A Character Index for Redpoll identification 

      January 5, 2008

      I've been thinking about redpolls more, and had another, more careful, look at Troy's 1985 paper, which is filled with interesting observations and some…

    • Parula Hybrids? 

      January 3, 2008

      I have had two inquiries about Tropical Parula in the last 24 hours, prompted by a bird currently in Austin, Texas. You can check out that bird in photos by…

    • A couple of Redpoll additions 

      January 2, 2008

      On the MOU website: a Hoary photo Here from Minnesota (where Hoary is expected and the threshold is low) of a pale Hoary-type with a relatively long billSome…

    • The Redpoll Questions 

      January 2, 2008

      More thoughts on redpolls after yesterday's post, prompted by my own nagging doubts and a query from Nick Anich: In all of this redpoll ID discussion, I think…

    • My Holiday (Redpoll) Photos 

      January 1, 2008

      Over the holidays I was able to spend a few days at my parents' house in upstate New York, and enjoyed the redpolls that were visiting the bird feeder. I saw…

    • More on Redpolls 

      January 1, 2008

      After my previous posts on redpolls here and here, I've had a chance to skim some of the redpoll literature, and it confirms that these are two very similar…

    • Perspective on a mystery bird 

      December 6, 2007

      Our perspective and the assumptions and decisions that are triggered by that point-of-view, strongly influence how we perceive the world around us. In short,…

    • Redpoll subspecies 

      December 4, 2007

      If identifying Hoary Redpoll is not enough of a challenge for you, maybe you'd like to look for subspecies of Hoary and Common Redpolls? First, check out…

    • Redpoll Identification 

      December 1, 2007

      Some updates 4 and 6 December -check out Jochen's comments and blog post here With the predicted superflight of finches beginning to develop (1st ever Common…

    • "Great White" Heron - not just a color morph 

      November 5, 2007

      Great White Heron Ardea herodias occidentalis updated 13 Nov 2007, thanks to all those who have commented publicly and privately. I've backed off a bit from…

    • Green-breasted Mangos in North America 

      October 31, 2007

      Green-breasted Mango Anthracothorax prevostii This species is not included in the Sibley Guide to Birds because at the time that I was planning the book…

    • Black Tern and White-winged Tern - leg color 

      September 5, 2007

      Another note from the comments under Sandwich Tern by Joseph Kennedy on 4 September, this deserves a separate discussion (Thanks, Joseph). He writes:I have…

    • Sandwich Tern - leg color 

      September 5, 2007

      In an interesting 4 September comment under the Sandwich Tern bill color discussion, Joseph Kennedy presents a photo of a juvenile Royal Tern with partly…

    • Judging size of birds 

      August 29, 2007

      Size judgment is one of the constant quandaries of bird identification - critically important but fraught with error. In a recent online discussion about these…

    • Olive-sided Flycatcher - white patches and age in fall 

      August 23, 2007

      Several recent Massachusetts reports of Olive-sided Flycatchers seem to have used the presence of white patches on the sides of the back to age the birds as…

    • Sandwich Tern - bill color of juveniles 

      August 23, 2007

      -- updated Sep 27, 2008This photo by Greg Lavaty of Texas, generated a lot of discussion on the Texas Birds listserv recently, and brings up some interesting…

    • Distinguishing Island and Western Scrub-Jays 

      July 10, 2007

      Feb. 10, 2005 In late October 2004 I was privileged to visit the Nature Conservancy's spectacular Santa Cruz Island preserve off the coast of Southern…

    • Distinguishing South Polar Skua and Pomarine Jaeger 

      July 9, 2007

      December 11, 2004 I was intrigued by this problem in light of the discussion surrounding the recent (6 November 2004) bird from southern Texas (see…

    • Identification of the Martha’s Vineyard Red-footed Falcon 

      July 7, 2007

      Illustration of the Red-footed Falcon perched. The smooth gray color is unlike any North American Falcon. Old juvenal wing and tail feathers are slightly…

    • Distinguishing Cackling and Canada Goose 

      July 7, 2007

      October 7, 2004 One of the most significant changes for birders in the 45th supplement of the AOU checklist (Banks et al., 2004) was the split of Canada…

  • Birds  (184)
    • Peter Pyle on Sage Sparrows 

      August 20, 2013

      The most significant change for North American birders in the 2013 AOU Checklist supplement is the split of Sage Sparrow into two species: Sagebrush Sparrow…

    • Another odd Snowy Egret, or a hybrid? 

      May 22, 2013

      Recently on Cape Cod, Massachusetts, Mary Keleher noticed an egret with two long head plumes, and took a couple of photos. This bird matches well with the ones…

    • Flycatcher identification by the calendar 

      April 12, 2013

      Here are some eBird maps showing all records for the month of April for several species of small flycatchers in eastern North America. A glance at these maps…

    • The white eyelid of American Dipper 

      April 9, 2013

      American Dipper showing off its white eyelid. Photographed near Cody, WY, March 2013, by David Sibley. It's one of the first things people notice when…

    • Pairs as an aid to hawk identification 

      March 4, 2013

      By the end of February, even in cold and snowy Massachusetts, Red-tailed Hawks are courting and forming pairs in preparation for nesting. It's common to…

    • Dark heron/egret 

      February 5, 2013

      Can you identify the two birds in this photo? It should be immediately obvious that this photo shows two species of dark herons, and their overall…

    • Posture and shape distinguishes male and female Dark-eyed Juncos 

      December 19, 2012

      Backyard Bird Discoveries While watching a small flock of juncos at my bird feeder on December 17, 2012, I noticed one particularly brownish female. Considerin…

    • My trick to finding Rusty Blackbirds 

      November 5, 2012

      Almost every Rusty Blackbird that I see in the eastern United States is in flight, so the simple trick is to look up. In order to do that you need to know what…

    • Quiz 53: Eastern Sparrows in early September 

      September 12, 2012

      Below are three sparrows photographed in Concord, MA on 11 Sep 2012. Can you identify the species? Today's quiz features a bonus Everyone who submits a…

    • In search of Spoon-billed Sandpiper 

      September 11, 2012

      Join me on a WINGS/Heritage Expeditions cruise 21 June to 4 July 2013 to search for nesting Spoon-billed Sandpipers in Siberia. I’ve always been fascinated…

    • Juvenal plumage of songbirds: Gray Catbird 

      September 8, 2012

      Most Passerines only hold juvenal plumage for a few weeks, quickly molting to a more adult-like plumage soon after they fledge and before fall migration. It's…

    • Quiz 51: Estimating Numbers 

      September 6, 2012

      Another quiz to test your skill at estimating numbers of birds in flocks.

    • Quiz 50: Bird topography - upperside 

      September 5, 2012

      Here is a new quiz about the topography of the upperparts of a large songbird.

    • Distinguishing immature (white) Little Blue Heron from Snowy Egret 

      August 18, 2012

      These are the only regularly occurring herons that are truly difficult to identify, as immatures of these two species are variable in bare-parts color and…

    • Identification of Waterthrushes 

      August 17, 2012

      First Glance A quick judgment of the ground color of the breast and eyebrow stripe will separate most waterthrushes: bright white on Louisiana, yellowish…

    • Quiz 48: Mystery Bird 

      August 16, 2012

      This bird was photographed in North America, and it's not some exotic vagrant.

    • Determining the age of white egrets and herons in late summer 

      August 15, 2012

      Identifying the white herons and egrets can be a challenge. We must rely mainly on structure, behavior, and the color of bare parts like bill and legs,…

    • A little-known bird sound 

      August 15, 2012

      This is a bird sound that I recorded in August in Massachusetts. Listen to the recording and see if you can guess what it is. Some hints are below, and when…

    • Quiz 47 - More estimating numbers 

      August 14, 2012

    • Quiz 46 - Estimating numbers 

      August 11, 2012

      Estimating numbers in flocks of birds is a skill that birders need to practice, but we rarely get a chance to test ourselves. We see a flock, guess the total…

    • Quiz 45 - Little Brown Bird Identification 

      August 10, 2012

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    • Quiz 44 - Bird flying away 

      August 9, 2012

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    • Why are Yellowlegs hard to identify? 

      July 26, 2012

      The flippant answer is "...because they look alike", and they can be very alike. Most of what you read about yellowlegs will tell you to look at bill…

    • Quiz 43: Still more songbird legs and feet 

      July 26, 2012

      Here are three more songbirds showing some of the variation in legs and feet. With thanks, again, to Brian E. Small for providing the beautiful photos. You…

    • Is it hard for hummingbirds to hover in the rain?  

      July 25, 2012

      Not really. A recently-published study used high-speed video of hummingbirds hovering in simulated rain to investigate questions of how hard it is to stay…

    • A Yellow Purple Finch in Ontario 

      July 25, 2012

      Thanks to reader Skip Pothier for sending in these photos. They show a Purple Finch with yellow color instead of red. My first thought was to call it a male…

    • Name changes of birds in the 2012 AOU supplement 

      July 24, 2012

      With the annual publication of the supplement to the AOU checklist, here is a listing of the changes to names in the Sibley Guide to Birds. There were a lot of…

    • Quiz 42: More topography of the upperparts 

      July 24, 2012

      Here is another quiz showing a bird viewed from behind, with questions about the feather groups that are visible. Notice how the contours of the back define…

    • Quiz 41: More identification by feet 

      July 20, 2012

      More examples of the variety of legs and feet – color and structure – that can be found among the small songbirds. With thanks, again, to Brian E.…

    • Quiz 40: Feather topography of the upperparts 

      July 18, 2012

    • Birds slow to react to predators because… the sun gets in their eyes  

      July 17, 2012

      An interesting study published recently found that cowbirds in bright sunlight were slower to detect predators, and cowbirds in shade were quicker. The…

    • A heron ID quiz 

      July 17, 2012

      Here is a photo of a white heron, taken by Constance Mier on the main shoreline of Biscayne Bay National Park, near Miami, Florida, on May 25, 2012. You…

    • Quiz 39: Bird ID by legs and feet 

      July 16, 2012

      The structure and color of birds' legs is extremely variable. Everyone knows the difference between the webbed foot of a duck and the unwebbed toes of a…

    • The joy of finger-painting 

      June 11, 2012

      The painting featured here was done during my recent birding workshop at the Pine Butte Guest Ranch in Montana, and is being auctioned to support the great…

    • Western Grebes can walk! 

      May 29, 2012

      In the Sibley Guide to Birds I wrote that Western and Clark's Grebes are "incapable of walking". I thought they could only push themselves along on their…

    • New art for auction 

      May 28, 2012

      I've just posted a new painting for auction. You can see the auction and closing time in the sidebar to the right. This is a small gouache painting of a…

    • More unusual Cattle Egrets 

      May 28, 2012

      After my post a few days ago about the unusual Cattle Egret in Florida, I heard from two people with interesting observations to add. Robert Edgar and…

    • Understanding Alarm Calls of Birds 

      May 27, 2012

      Among the many benefits of paying attention to bird sounds is that they give you an insight into what the birds are doing. Through their songs and calls the…

    • Quiz 38: More feathers, and a prize 

      May 24, 2012

      Today's quiz features a bonus And we have a winner - Congratulations to Nicholas! Thanks to all who entered. Watch for another quiz giveaway in the near…

    • Quiz 37: Bird topography 

      May 23, 2012

      Test your knowledge of bird feather topography with the questions below.

    • An unusual Cattle Egret in Florida  

      May 22, 2012

      In late April 2012, Roy Halpin found and photographed an entirely buff-colored Cattle Egret in Saint Augustine, Florida. This is a particularly interesting…

    • Bird Song ID series continues - Eastern Trills 

      May 18, 2012

      The next part of my introduction to learning bird songs is now up (click here). Birds can hear a lot “faster” than we can, however, and consequentl…

    • Bird songs Part 5: Describing Quality 

      May 14, 2012

      Part 5 of my introduction to learning bird songs is now up (click here). Many of the words that we use to describe the quality of a bird song also…

    • Part 4: Understanding Quality in bird song 

      May 11, 2012

      Part 4 of my introduction to learning bird songs is now up (click here). In the narrowest sense, the quality of a bird’s voice would refer strictly…

    • Quiz 36: More Warblers 

      May 10, 2012

      Today's quiz features a bonus And we have a winner! Congratulations to Laramie, and thanks to everyone who entered! There will be another quiz giveaway…

    • Tempo, and bird song identification 

      May 8, 2012

      Part 3 of my introduction to learning bird songs is now up (click here). In this discussion, tempo refers to the overall “pace” of the song, the…

    • Quiz 35 - More warblers from below 

      May 7, 2012

      Like a previous quiz this one shows warblers as they are so often seen in the field - with just the underside of the body visible. Clues such as tail shape,…

    • Pitch, and bird song identification 

      May 4, 2012

      Pitch is simply our perception of the frequency (or wavelength) of a sound, which we describe as high to low. Birds’ range of hearing is similar to our own,…

    • Quiz 34 - Brightly-colored Birds 

      May 3, 2012

      Here are five species of intensely colorful spring birds. Can you identify them from just the small parts that are visible? Today's quiz features a…

    • Quiz 33: Small songbirds by their wings 

      May 2, 2012

      This quiz shows just the bodies of five species of small drab songbirds with wingbars. In other quizzes I've given a big clue in the form of telling you the…

    • The annual plumage cycle of a male American Goldfinch 

      May 1, 2012

      Molt is the process of feather replacement. All birds do it; they have to grow new feathers once or twice a year to stay warm, dry, and airborne, and in many…

    • Quiz 32 - Warblers from below 

      May 1, 2012

      This quiz shows warblers as they are so often seen in the field - with just the underside of the body visible. Clues such as tail shape, overall size,…

    • Mystery Bird Song - Concord, MA 

      April 29, 2012

      I recorded this sound (with my iPhone, please excuse the poor quality) on 29 April 2012 near my house in Concord, MA. Have a listen and see what you think. For…

    • Quiz 31: More warblers by partial cues 

      April 27, 2012

      Here are some partially obscured warblers to test your knowledge. Look especially at the pattern of wingbars to distinguish these three. With thanks,…

    • In praise of mystery 

      April 26, 2012

      The still-unidentified Elaenia, found by Ethan and Aaron Gyllenhaal in Illinois, has provided one of the most exciting and interesting bird identification…

    • Quiz 30: Comparing bird weights 

      April 24, 2012

      Continuing the challenge of comparing bird weights, here are some familiar species to test your knowledge.

    • Quiz 29: Comparing bird weights 

      April 23, 2012

      Today's quiz revisits the challenge of comparing bird weights. In the field we get a sense of the "bulk" of a bird, and that is a very important part of…

    • Bird Topography - How it helps identify birds 

      April 16, 2012

      I was musing on the value of learning bird topography this morning, wondering why it is so important to know the greater coverts and supercilium and all the…

    • Quiz 28: More Warblers 

      April 13, 2012

      Update: Congratulations to Vjera, the winner of this week's prize drawing! Thanks to all who entered. Watch for another giveaway next week. The quiz prize…

    • Quiz 26: Warblers and head patterns 

      April 10, 2012

      This week's quizzes will be looking at some warblers, in anticipation of the spring migration. With thanks, again, to Brian E. Small for providing the…

    • Quiz 25: Wing patterns 

      April 6, 2012

      Update: Congratulations to Alvan, the winner of the Backyard Birds poster. Thanks to all who took the quiz and entered. The response was fantastic, and keep…

    • Quiz 24: Wing Patterns 

      April 5, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 23: Wing patterns 

      April 4, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 22: Wing patterns 

      April 3, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 21: Wing patterns 

      April 2, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Announcing my new video guide to bird songs! 

      April 1, 2012

      Update: For future visitors I should explain that I posted this as an April Fool's Joke. This video converts the voice descriptions from the Sibley Guide to…

    • The Sibley eGuide is now available for Blackberry Playbook 

      March 29, 2012

      Just released and available for download at the Blackberry App World - The Sibley eGuide can now be used on any Blackberry Playbook tablet. All of the features…

    • Identification of female bluebirds by wing structure 

      March 27, 2012

      A pale and grayish female bluebird found in North Carolina recently (March 2012) provided a very interesting identification challenge. The plumage colors were…

    • Quiz 20: Wings, long and narrow 

      March 15, 2012

      This quiz groups some relatively long and narrow wings. Pay special attention to subtle differences in shape, and bold white patterns. With thanks to the…

    • All wings are the same, in some ways 

      March 13, 2012

      Here is a quiz with three very different wings, and a detailed explanation follows (don't peek). With thanks to the online wing collection of the Slater…

    • Quiz 18: Blue bird parts 

      March 12, 2012

      This quiz shows just parts of three different blue birds. Try to identify the species while seeing only part of the body. With thanks, again, to Brian E.…

    • Off to Belize 

      March 11, 2012

      I'll be away in Belize for the next week or so, leading a trip for Mass Audubon, and in anticipation of that I've posted a photo of one of the most iconic…

    • Wings, above and below  

      March 10, 2012

      Most birds have a very different pattern on the upperside and underside of their wings. On the coverts (the leading edge of the wing) this is easily explained…

    • Quiz 17: Western birds in part 

      March 9, 2012

      Here's a new variation for an ID quiz. Birds in these photos are mostly masked by black. See if you can identify the species without seeing the whole bird. W…

    • Sibley eGuide for Windows Phone 7 - now available 

      March 7, 2012

      Just released and available for download at the Windows Phone Marketplace - The Sibley eGuide can now be used on any device running Windows Phone 7. All of the…

    • A head feather survey 

      March 7, 2012

      Update: 9 March 2012 Thank you! The response to the head feather survey has been fantastic: 95 participants as of 10 AM on March 9th. The survey will be…

    • What is the submoustachial? 

      March 7, 2012

      The feathers along the side of the lower jaw have a very confusing history of terminology. They've been called the malar stripe (in many early and mid 20th…

    • Quiz 15: The submoustachial 

      March 6, 2012

      Regardless of what you call them – submoustachial, malar, jaw stripe, mandibular stripe – the feathers along the side of the lower jaw are important for…

    • Variation in head pattern 

      March 5, 2012

      In recent posts and quizzes here I've been stressing the head feather groups, and how they provide a consistent structure for understanding the color patterns…

    • The changeable shape of the supercilium 

      March 3, 2012

      The feathers that grow on the sides of the head above the eyes of a bird are called the supercilium, and when they contrast in color with the adjacent feathers…

    • Quiz 13: Head pattern variations 

      March 2, 2012

      Here are four more birds with questions about their head feathers. With thanks, again, to Brian E. Small for providing the beautiful photos. You can see…

    • Quiz 12: More on head feathers 

      February 29, 2012

      A teaser of spring wood-warblers on this bonus day of February. Two questions for each of the photos will help you practice applying your knowledge of head…

    • Trumpeter Swans, yellow bill spots, and leucism 

      February 29, 2012

      In a previous post I've talked about Trumpeter Swans with yellow bill spots as a source of  confusion with Tundra Swan. I speculated that the yellow spots…

    • Introduction to breast feathers 

      February 28, 2012

      One of the well-defined groups of feathers on the underside of a bird is what we call the breast. In reality, on songbirds these feathers grow from the…

    • Rare birds "under the radar" 

      February 24, 2012

      In previous posts here I've asked "How many rare birds do we miss?" and the related question "How many rare birds do we find?" Several recent rare bird…

    • Quiz 11: Head feather groups and simple color patterns 

      February 22, 2012

      This quiz is about taking the feather groups you've learned in previous quizzes, and applying them to real birds, to see how color patterns follow the basic…

    • Quiz 10: Head feathers - without markings 

      February 21, 2012

      This quiz features a Dark-eyed Junco, a species with no discernible color pattern on the head. How can you distinguish groups of head feathers with no color…

    • Rough-legged vs. Red-tailed? 

      February 21, 2012

      The other morning I was passing a farm field near my house. It's a place where I often go birding and as I glanced around I was thinking "maybe there could…

    • Quiz 9: More on Head feathers 

      February 20, 2012

      Here is a close-up of the head of a Song Sparrow, showing the feather groups and feather markings really well. In the copy below, I've outlined the feather…

    • Quiz 8: Introduction to head feathers 

      February 16, 2012

      Color patterns on the heads of birds are some of the most complex, and also some of the most important for identification. Understanding those patterns is…

    • Quiz 7: more on bird weights, with a twist 

      February 15, 2012

      In this quiz your challenge is to compare the weight of the birds with common household items. There is variation in the weight of the birds, and variation in…

    • It's right where I'm looking! 

      February 14, 2012

      or: How to point out the location of a bird Discussions of birding techniques dwell mainly on finding and identifying birds, as they should, but as soon as…

    • Quiz 6: Bird weight 

      February 13, 2012

      Below is a chance to test your knowledge of bird size, by selecting the heavier species in each of five pairs of birds. Weight, or apparent bulk, is one of the…

    • Quiz on Bird Topography: Wings 3 

      February 10, 2012

      Each label in the photo above points to a feather group associated with the wings. In the quiz below, choose the correct name for that labeled feather…

    • Quiz on Bird Topography: Wings 2 

      February 8, 2012

      Identify the two labeled feather groups in the quiz below, with a couple of bonus questions.

    • Painting a Saw-whet Owl 

      February 8, 2012

      Yesterday I painted a Northern Saw-whet Owl of the very distinctive Queen Charlotte Islands subspecies A. a. brooksi, which was inexplicably left out of the…

    • A quiz on bird wing feathers 

      February 7, 2012

      The major groups of feathers on the wing are showing well on this American Robin, and each is labeled with a letter. In the quiz below, select the letter…

    • Backyard Bird Quiz: part II 

      February 6, 2012

      Here's the next installment in quizzes. I've removed the titles this time so hovering over the image shouldn't give it away (but some browsers will still show…

    • Variation in immature American Herring Gulls 

      February 3, 2012

      A recent discussion about geographic variation in Herring Gulls (on the ID-Frontiers listserve) prompted me to go back and scan some photos I took in 1998 at…

    • New feature: a bird identification quiz 

      February 1, 2012

      Identify the species shown in each photo by clicking the multiple choice answers. I hope to make short quizzes like this a regular feature of this website, so…

    • The two stages of field identification 

      January 30, 2012

      As I work on the revision of my field guide I've been giving a lot of thought to how the book can assist the process of identification, and what information is…

    • A Wurdemann's-like heron from South Florida 

      January 25, 2012

      Thanks to reader Anne DuPont for sending in these photos of a pair of Great Blue Herons at Wakodahatchee Wetlands, Delray Beach, Florida. It's clearly a mated…

    • The origin of the Snowy Owl invasion  

      January 23, 2012

      Snowy Owls are making news this winter, as in the New York Times today (link) The conditions setting up this invasion started at least a year ago. Last…

    • Sibley eGuide available for Kindle Fire 

      January 20, 2012

      The Sibley eGuide to birds was recently adapted for the Kindle Fire tablet (and still works on other Android OS devices). You can find it at the Amazon app…

    • Identifying sleeping female goldeneyes 

      January 20, 2012

      Like many other species of ducks that are distinguished by head shape, Common and Barrow's Goldeneyes are at least as easy to tell apart when sleeping as when…

    • Distinguishing male and female American Goldfinches 

      January 19, 2012

      For much of the year, distinguishing male and female American Goldfinches is easy (when the males show their brilliant yellow summer plumage, about March…

    • Subspecies of Scaled Quail 

      January 17, 2012

      There are four named subspecies of Scaled Quail, three in the US and one in Mexico. The subspecies found in southern Texas is distinctly different from the…

    • Do "dwarf" birds exist? 

      January 13, 2012

      A recent discussion on the ID-Frontiers listserver involved an immature gull photographed in Utah (photo by Norman Jenson here). The consensus (and I agree) is…

    • Identification of white geese 

      December 7, 2011

      Recent discussion of the identification of a white goose in Ohio (beginning here) prompted me to put together some sketches of bill shapes of Ross's and Snow…

    • eGuide update - Redesigned for iPad! 

      December 5, 2011

      The Sibley eGude to Birds for iPhone and iPad has been updated to be a universal app. The new version takes advantage of the full screen of the iPad to show…

    • Overconfidence 

      October 27, 2011

      A recent article by Tim Enthoven in the New York Times - Don’t Blink! The Hazards of Confidence - offers some fascinating thoughts on judgment, expertise,…

    • Does technology make birders lazy? 

      October 26, 2011

      In a recent post at the ABA blog, a new smartphone app is described that promises to help identify bird songs in the field. Bird song identification software…

    • On identifying Chipping and Clay-colored Sparrows 

      October 25, 2011

      I recently commented on this ID problem on MassBird, pointing out differences in details around the eyes. Chipping sparrow has very distinct, narrow whitish…

    • The basics of iridescence in hummingbirds 

      September 20, 2011

      After all the discussion of orange-throated and red-throated hummingbirds, I thought it would be helpful to add a brief and simplified summary of how the…

    • Progress on the orange-throated hummingbird mystery 

      August 16, 2011

      Thanks to Sheri Williamson (author of the Peterson Field Guide to Hummingbirds) and her recent post titled Orange-throated hummingbirds - not so mysterious…

    • The finer points of wing translucence  

      August 15, 2011

      Patterns of translucence in wing feathers provide useful identification clues for many species of birds - terns, gulls, hawks, and others. Generally the…

    • Orange-throated Hummingbirds: more questions 

      August 14, 2011

      Now updated by a new post Progress on the Orange-throated hummingbird mystery. This adds to my previous post about orange-throated hummingbirds. After…

    • Abnormal coloration in birds: Melanin reduction  

      August 5, 2011

      Albino and partial albino birds The presence of white feathers on a normally dark bird is the most frequently seen color abnormality. Every birder can…

    • The mystery of the orange-throated hummingbirds  

      August 4, 2011

      Update 16 August: a new post Progress on the orange-throated hummingbird mystery. Update 14 Aug 2011: A follow-up to this post is now available,…

    • New bird names in the 52nd AOU Checklist supplement  

      July 30, 2011

      The North American Checklist Committee of the AOU has published the 52nd supplement to the AOU Checklist of North American Birds. This supplement includes…

    • Can Short-tailed Shearwater be identified in the field? 

      July 30, 2011

      Usually. Experienced observers can almost always identify these species correctly based on careful judgment of head shape and bill size, but these are subtle…

    • Distinguishing Eurasian and American Common Merganser 

      July 29, 2011

      The Eurasian subspecies group of Common Merganser, known by the English name Goosander, has occurred numerous times in the Aleutian Islands of western Alaska,…

    • Trumpeter Swans with yellow loral spots 

      July 25, 2011

      The photo above was recently sent to me by reader Wil Domke. It shows an adult Trumpeter Swan (based on bill size and shape, and on Wil's identification in…

    • The mysterious dark Least Bittern 

      July 23, 2011

      Dark morph (Cory's) Least Bittern Note: I have never personally seen a living Cory's Least Bittern. In fact, only six or so have been seen during my lifetime.…

    • Does Blackpoll Warbler have song dialects? 

      July 1, 2011

      I've been aware of some variation in songs of Blackpoll Warbler for many years, and now an interesting post by Andrew Spencer at Earbirding prompted me to…

    • Powder down and the Black-crowned Night-Heron  

      June 29, 2011

      In a footnote here I mentioned that blackish feathers can appear gray because of powder down, and now I will offer a little more explanation. Powder…

    • Does Cattle Egret have a dark morph?  

      June 28, 2011

      On 18 May 1987, while birding at Cape May, NJ, I came across a small group of Cattle Egrets foraging in a field. Accompanying them was the bird in the photos…

    • A Mystery Sound 

      June 24, 2011

      23 Jun 2011 – Concord, MA Sitting at my desk today I was roused by a bird call that I did not immediately recognize. This is a very rare occurrence for me,…

    • The new Wood-Warbler taxonomy  

      June 23, 2011

      No more Dendroica? If you're connected to the birding grapevine, you've probably already heard that the AOU has rearranged the species of Wood-Warblers…

    • New efforts to save Spoon-billed Sandpiper 

      June 7, 2011

      There is more evidence of the dire situation with Spoon-billed Sandpiper – efforts are currently underway to develop a captive-breeding population. A…

    • A "mystery" oriole and the limitations of identification by impression 

      May 19, 2011

      On 9 May 2011 several birders saw and heard a strange oriole in Georgetown, South Carolina (photos here). They identified it as a Scott's Oriole, a first state…

    • Intergradation between Mexican Duck and Mallard in Arizona 

      May 6, 2011

      The Mexican Duck was formerly considered a species (Anas diazi), and is currently lumped with Mallard (as subspecies Anas platyrhynchos diazi), but recent DNA…

    • Dark-fronted Cliff Swallows in Louisiana and Mississippi 

      April 11, 2011

      It's time to revisit the variation in Cliff Swallows along the Gulf Coast – with dark-fronted Cliff Swallows nesting in southern Mississippi and…

    • The Proper Use of Playback in Birding  

      April 7, 2011

      A Korean translation of this post is here With the recent surge in the availability of digital audio devices, the use of playback to attract birds into view…

    • Vocal copying by American Robin  

      April 5, 2011

      On 5 April 2011 in Concord Massachusetts I was walking the edge of a field where I often go birding, and heard very distinctly the sputtering call of an…

    • Sibley Guide in action - Redpoll Identification 

      April 1, 2011

      Not an April Fool's joke, this is a real photo taken today by Scott Young in New Hampshire (Thanks, Scott). Clicking the photo links to his Flickr site where…

    • Carolina Wren mystery spots 

      March 30, 2011

      Reader Richard Messer sent me the photos below, asking if I knew what the behavior was that displayed the white "rump spots" of the Carolina Wren. My answer is…

    • Identifying subspecies by behavior - Savannah Sparrow 

      March 28, 2011

      Identifying subspecies adds richness to your birding by adding another layer of understanding. What’s more, during spring migration, behavior can offer a…

    • Distinguishing Green-winged and Common Teal 

      March 26, 2011

      The Green-winged Teal (known as Common Teal in English-speaking parts of Eurasia) is currently considered a single species by the AOU, but two subspecies are…

    • Distribution of Greater White-fronted Goose subspecies 

      March 24, 2011

      The Greater White-fronted Goose (Anser albifrons) occurs throughout much of North America, but is found in largely disjunct populations. Only two North…

    • Distinguishing the subspecies of Purple Finch  

      March 22, 2011

      Summary The two subspecies of Purple Finch are fairly distinctive with well-defined ranges. They are best distinguished by overall impression of…

    • Can subspecies of Mountain Chickadee be identified in the field?  

      March 22, 2011

      Not really. Only under ideal conditions and with reference to location. Mountain Chickadee is found throughout much of the montane coniferous forest…

    • Identifying songbirds by flocking behavior  

      March 16, 2011

      It's early morning and you're out on a bird walk following your guide under a gray sky. A flock of small songbirds flits over the distant treetops. The…

    • The 'Caribbean' Coot in North America 

      March 15, 2011

      Caribbean Coot Fulica caribaea (found sparingly and locally in the West Indies from Hispaniola south and east to the coast of Venezuela) is virtually…

    • Another clue for identifying Downy and Hairy Woodpeckers 

      March 14, 2011

      In a previous post I wrote about differences in the black-and-white pattern on the neck of Downy and Hairy Woodpeckers, and in comments there Dan Lane reminded…

    • Identifying small songbirds by flight style  

      March 11, 2011

      It's easy. Experienced birders do it subconsciously, using clues from the wingbeats, rhythm, and path of a bird's flight. These are usually described in vague…

    • Bird species new to North America - a summary 

      March 8, 2011

      New birds are being added to the North American list at a steady rate, and there is no reason to think that the pace of discovery will slow. Some birds are…

    • Identifying Downy and Hairy Woodpeckers by drumming sounds 

      March 3, 2011

      Instead of song, most woodpeckers use a mechanical drumming sound as their audio advertising display. It's easy to tell when you hear a woodpecker, harder to…

    • Sparrows and central spots 

      February 25, 2011

      Can you identify the sparrow shown in this photo? Read on for the discussion and answer below. Thanks to Jerry Tang for the photo and for bringing it to my…

    • Can Eurasian Common Moorhen be identified by sight? 

      February 17, 2011

      Maybe, it depends how sure you want to be. Update July 2011 - See my new post on Back color of Moorhens for an additional clue to identification …

    • A new clue for identifying Downy and Hairy Woodpeckers 

      February 16, 2011

      A few years ago I was alerted to a subtle difference in the head patterns of Downy and Hairy Woodpeckers when I read a short note by Mark Szantyr with a nod…

    • Identifying scoters by shape 

      February 12, 2011

      I was recently studying and sketching the three species of American scoters in Revere, Massachusetts, and I was struck by the differences in head and body…

    • Still more examples of false faces in birds 

      February 7, 2011

      In two previous posts  (The two faces of Downy Woodpecker and More false faces in birds) I’ve talked about the false faces created by feather patterns on…

    • Variation in Brown Creeper songs 

      January 29, 2011

      This post accompanies: Is the Brown Creeper more than one species? The songs of Brown Creepers do vary regionally, but the variation is subtle and complex…

    • Is the Brown Creeper more than one species? 

      January 28, 2011

      Brown Creeper is such a familiar and easily-identified bird that few birders really study it closely. Slight regional differences in plumage and song have…

    • Donate to help Spoon-billed Sandpiper  

      January 20, 2011

      The painting shown here is currently available at auction (see box at right, revised on 24 Jan) with 100% of the proceeds going to support the efforts of…

    • Possible hybrid sandpiper in Kenya 

      January 10, 2011

      In December 2010 I had the privilege of birding in Kenya with the incomparable Brian Finch, and on 14 December we stumbled upon an interesting small sandpiper…

    • A perplexing shrike  

      December 3, 2010

      A shrike present on Long Island NY October-November 2010 was originally (and understandably) identified as a Northern. it received wider attention after Shai…

    • White-crowned Sparrow subspecies - Where? 

      November 12, 2010

      There are five subspecies of White-crowned Sparrow, and in most parts of North America it is possible to see more than one subspecies during part of the year.…

    • Questions about Starling migration 

      November 11, 2010

      The European Starling is often ignored, or worse, by North American birders, but if you can get past the fact that it's aggressive, very good at living with…

    • Red pouches on Brown Pelicans 

      October 25, 2010

      In the Sibley Guide to Birds I illustrated Pacific and Atlantic/Gulf populations of Brown Pelican, showing different colors on the throat pouch (red on adult…

    • Identifying Chimney and Vaux's Swifts by wing shape 

      October 11, 2010

      For most observers the identification of these two species is simple, and is based entirely on location, with Vaux's in the west and Chimney in the east. It is…

    • You too can record and identify Crossbill call types 

      October 5, 2010

      If you've followed any of the discussions about identifying Red Crossbill call types, you may have given up on taking an active role in crossbill study,…

    • Bill size, not shape, distinguishes Cackling and Canada Goose 

      September 26, 2010

      I recently checked the bill length to bill depth ratios of Cackling and Canada Geese, expecting to find a consistent and useful difference. The bills of…

    • Wing twisting explained 

      September 24, 2010

      In discussing the identification of the woodpecker in the Luneau video, my colleagues and I suggested that the extensive white visible in the wings could be…

    • Variation in juvenal plumage of Red Crossbill 

      September 21, 2010

      In my last post I mentioned that the juvenal plumage of type 4 and type 2 Red Crossbills seemed to be consistently different, and here are two photos that…

    • New York Times on windows and birds 

      August 31, 2010

      An article in the Aug 28, 2010 edition of the New York Times - Warning to Birds: All-Glass Buildings Ahead - describes recent developments in window…

    • Distinguishing Pacific and Winter Wrens 

      August 13, 2010

      These two species (recently split) are extremely similar in appearance. No significant differences exist in size or shape, and plumage differences are subtle…

    • New bird names in the 51st AOU Checklist supplement 

      July 29, 2010

      The North American Checklist Committee of the AOU has published the 51st supplement to the AOU Checklist of North American Birds, which includes two major…

    • Variation in immature Ring-billed Gulls - April 

      May 14, 2010

      Updated 19 May 2010 to add McLaughlin referencePreviously I wrote about the variation in immature Ring-billed Gulls in October, using a series of photos from…

    • Updates on Spoon-billed Sandpiper 

      April 21, 2010

      Be sure to sign up at 10,000 Birds for your chance to win an original David Sibley painting of Spoon-billed Sandpiper – and help bird conservation efforts at…

    • The next 10 North American bird splits 

      April 16, 2010

      A favorite activity among avid birders is speculating and pontificating about which species should be "split" into new species (and new checkmarks on the…

    • A chance to own an original painting of Spoon-billed Sandpiper 

      April 13, 2010

      I've donated this original painting of Spoon-billed Sandpiper which is being given away over at 10000 Birds. In order to have a chance to win it all you have…

    • New Folding Guides to birds 

      March 31, 2010

      The Sibley Guide to Birds is now available in a series of eight laminated "folding guides" to birds. They can be found in many book and nature shops for .95…

    • More false faces in birds 

      March 27, 2010

      In a previous post I wrote about false faces in birds, using the example of a Downy Woodpecker to show how color patterns create the illusion that the bird is…

    • Subspecies by phenology - Great Blue Heron 

      March 3, 2010

      Phenology is the study of the timing of natural events, and I have recently begun to realize how useful it is for distinguishing subspecies of birds. In San…

    • The two faces of Downy Woodpecker 

      February 25, 2010

      A few species of birds with false eyespots are well-known: pygmy-owls and American Kestrel come to mind. In these species of birds, spots on the back of the…

    • Kingbirds, nightjars, and the perception of bird sounds 

      December 10, 2009

      In a recent post on his excellent blog Earbirding, Nathan Pieplow points out an issue with the voice description of Buff-collared Nightjar in the Sibley…

    • Variation in immature Ring-billed Gulls 

      December 1, 2009

      On October 9th, 2005 I was enjoying the view at First Encounter Beach in Eastham, Massachusetts and watching a small flight of seabirds. A flock of gulls began…

    • Obsolete Bird Names 

      October 19, 2009

      Have you seen any Field Plovers lately? Blue Nutcrackers? Day Owls? These are all alternate common names of North American birds. Richard Banks has assembled a…

    • Updated bird names for The Sibley Guide to Birds 

      October 9, 2009

      This list covers changes (through Nov 2009) to the official names of birds as published by the American Ornithologist’s Union (AOU) in periodic supplements…

    • Corrections to 4th printing of the Sibley Guide to Birds 

      October 8, 2009

      The following list details corrections made in 2001 in the 4th printing of The Sibley Guide to Birds. If you own a 1st or 3rd printing you can make these…

    • Probability in bird identification 

      October 1, 2009

      One of my regular birding spots is a small farm field near my house in Concord, Massachusetts. I can walk around the entire place in about 20 minutes, but I…

    • Identification of the Martha’s Vineyard Red-footed Falcon 

      July 7, 2007

      Illustration of the Red-footed Falcon perched. The smooth gray color is unlike any North American Falcon. Old juvenal wing and tail feathers are slightly…

  • Tree Identification  (10)
    • Quiz 52: Trees for birders 

      September 10, 2012

      The quiz below shows four photographs of the leafy crowns of trees, as you might see them while looking for birds through binoculars or telescopes. Difference…

    • Trees in their spring colors 

      May 11, 2012

      I've been neglecting trees in my posts recently, but here in Massachusetts spring is the best time of year for tree-watching, and today the sun was out…

    • Spruce, Fir, or Hemlock? 

      February 26, 2011

      One of my main goals in creating the Sibley Guide to Trees was to apply modern methods of bird study to tree identification. This meant looking at trees at a…

    • Identifying trees by color 

      April 13, 2010

      Spring is always an exciting time for birdwatchers, as migrants pass through and summer residents return, all in their flashy breeding plumage. This time of…

    • The meaning of "two-ranked" 

      March 30, 2010

      In The Sibley Guide to Trees I refer to some species of trees as having leaves (or needles) two-ranked, and several readers have asked me to clarify the…

    • Variation in shape of Hickory nuts 

      November 30, 2009

      Thanks to an email from Ray Telfair I've taken a closer look at the illustrations and descriptions of hickory nuts on pages 143 to 149 in the Guide to…

    • Variation in fall color: Red Maple 

      November 24, 2009

      Watching the changing colors of fall leaves is always interesting, and even more so when you recognize the species of trees and begin to understand some of the…

    • Evergreens have fall color too 

      November 9, 2009

      In fall it is the bright red and yellow colors of the broadleaf trees that get all the attention from "leaf-peepers". Much more subtle and largely unnoticed…

    • Corrections to The Sibley Guide to Trees 

      October 14, 2009

      Here are page-by-page corrections and changes for The Sibley Guide to Trees. This listing will be updated periodically as issues come to my attention.…

    • Trees with opposite leaves 

      October 3, 2009

      In the past, tree identification guides have emphasized the presence of opposite leaves as one of the most important field marks. In the Sibley Guide to Trees…

  • Trees  (14)
    • Quiz 52: Trees for birders 

      September 10, 2012

      The quiz below shows four photographs of the leafy crowns of trees, as you might see them while looking for birds through binoculars or telescopes. Difference…

    • Altruistic trees! 

      July 23, 2012

      It turns out that trees not only communicate through fungal networks in their roots, they also pass nutrients around from tree to tree, even between species!…

    • Trees in their spring colors 

      May 11, 2012

      I've been neglecting trees in my posts recently, but here in Massachusetts spring is the best time of year for tree-watching, and today the sun was out…

    • Spruce, Fir, or Hemlock? 

      February 26, 2011

      One of my main goals in creating the Sibley Guide to Trees was to apply modern methods of bird study to tree identification. This meant looking at trees at a…

    • Identifying trees by color 

      April 13, 2010

      Spring is always an exciting time for birdwatchers, as migrants pass through and summer residents return, all in their flashy breeding plumage. This time of…

    • The meaning of "two-ranked" 

      March 30, 2010

      In The Sibley Guide to Trees I refer to some species of trees as having leaves (or needles) two-ranked, and several readers have asked me to clarify the…

    • Original art of Sugar Maple 

      March 1, 2010

      Here's an opportunity to own a piece of my original art. I have donated an original acrylic painting of the leaf and fruit of Sugar Maple to Mass Audubon's…

    • New page on Tree references 

      January 19, 2010

      I've just posted a new page that lists some of my most-frequently-used online references about trees. You can find it here, and it is also linked on the Tree…

    • Variation in shape of Hickory nuts 

      November 30, 2009

      Thanks to an email from Ray Telfair I've taken a closer look at the illustrations and descriptions of hickory nuts on pages 143 to 149 in the Guide to…

    • Variation in fall color: Red Maple 

      November 24, 2009

      Watching the changing colors of fall leaves is always interesting, and even more so when you recognize the species of trees and begin to understand some of the…

    • A modern (holistic) approach to Tree Identification 

      November 10, 2009

      Through this fall I've been talking about what I tried to accomplish in my new Guide to Trees. In essence, I tried to approach tree identification in the same…

    • Corrections to The Sibley Guide to Trees 

      October 14, 2009

      Here are page-by-page corrections and changes for The Sibley Guide to Trees. This listing will be updated periodically as issues come to my attention.…

    • Trees with opposite leaves 

      October 3, 2009

      In the past, tree identification guides have emphasized the presence of opposite leaves as one of the most important field marks. In the Sibley Guide to Trees…

    • My latest project 

      September 10, 2009

      After seven years of work, my new Guide to Trees goes on sale officially on September 15th (but those who live near Philadelphia can get it as early as…

  • Birding Skills  (66)
    • Quiz on Belizean Birds and Greater Coverts 

      February 20, 2014

      Find the Greater Secondary Coverts These are some of my digiscoped photos from a recent trip to Belize, all taken at the fantastic Black Rock Lodge. On…

    • Pairs as an aid to hawk identification 

      March 4, 2013

      By the end of February, even in cold and snowy Massachusetts, Red-tailed Hawks are courting and forming pairs in preparation for nesting. It's common to…

    • Can you find the Cackling Goose?  

      November 16, 2012

      One of the biggest challenges of identifying a Cackling Goose is just finding one, especially in the east where the species is rare and occurs mostly as single…

    • Quiz 52: More numbers 

      September 11, 2012

      Here are three more "flocks" of lentils that need to be estimated. If you need an extra challenge, give yourself a time limit to come up with each number.

    • Juvenal plumage of songbirds: Gray Catbird 

      September 8, 2012

      Most Passerines only hold juvenal plumage for a few weeks, quickly molting to a more adult-like plumage soon after they fledge and before fall migration. It's…

    • Quiz 51: Estimating Numbers 

      September 6, 2012

      Another quiz to test your skill at estimating numbers of birds in flocks.

    • Quiz 50: Bird topography - upperside 

      September 5, 2012

      Here is a new quiz about the topography of the upperparts of a large songbird.

    • Quiz 49: Estimating numbers of birds 

      August 21, 2012

      This time the answers are arranged randomly, instead of sequentially, and I think this makes it a little harder, since it's harder to use the range of possible…

    • Quiz 47 - More estimating numbers 

      August 14, 2012

    • Quiz 46 - Estimating numbers 

      August 11, 2012

      Estimating numbers in flocks of birds is a skill that birders need to practice, but we rarely get a chance to test ourselves. We see a flock, guess the total…

    • Why are Yellowlegs hard to identify? 

      July 26, 2012

      The flippant answer is "...because they look alike", and they can be very alike. Most of what you read about yellowlegs will tell you to look at bill…

    • Understanding Alarm Calls of Birds 

      May 27, 2012

      Among the many benefits of paying attention to bird sounds is that they give you an insight into what the birds are doing. Through their songs and calls the…

    • Quiz 38: More feathers, and a prize 

      May 24, 2012

      Today's quiz features a bonus And we have a winner - Congratulations to Nicholas! Thanks to all who entered. Watch for another quiz giveaway in the near…

    • Quiz 37: Bird topography 

      May 23, 2012

      Test your knowledge of bird feather topography with the questions below.

    • The annual plumage cycle of a male American Goldfinch 

      May 1, 2012

      Molt is the process of feather replacement. All birds do it; they have to grow new feathers once or twice a year to stay warm, dry, and airborne, and in many…

    • Bird Topography - How it helps identify birds 

      April 16, 2012

      I was musing on the value of learning bird topography this morning, wondering why it is so important to know the greater coverts and supercilium and all the…

    • Quiz 25: Wing patterns 

      April 6, 2012

      Update: Congratulations to Alvan, the winner of the Backyard Birds poster. Thanks to all who took the quiz and entered. The response was fantastic, and keep…

    • Quiz 24: Wing Patterns 

      April 5, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 23: Wing patterns 

      April 4, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 22: Wing patterns 

      April 3, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • All wings are the same, in some ways 

      March 13, 2012

      Here is a quiz with three very different wings, and a detailed explanation follows (don't peek). With thanks to the online wing collection of the Slater…

    • Wings, above and below  

      March 10, 2012

      Most birds have a very different pattern on the upperside and underside of their wings. On the coverts (the leading edge of the wing) this is easily explained…

    • Quiz 16: Identifying blue wings 

      March 8, 2012

      Wings are amazing. Marvels of engineering, with intricate and changeable color patterns, they offer endless avenues for study. But seeing the details of a wing…

    • What is the submoustachial? 

      March 7, 2012

      The feathers along the side of the lower jaw have a very confusing history of terminology. They've been called the malar stripe (in many early and mid 20th…

    • Quiz 15: The submoustachial 

      March 6, 2012

      Regardless of what you call them – submoustachial, malar, jaw stripe, mandibular stripe – the feathers along the side of the lower jaw are important for…

    • Variation in head pattern 

      March 5, 2012

      In recent posts and quizzes here I've been stressing the head feather groups, and how they provide a consistent structure for understanding the color patterns…

    • The changeable shape of the supercilium 

      March 3, 2012

      The feathers that grow on the sides of the head above the eyes of a bird are called the supercilium, and when they contrast in color with the adjacent feathers…

    • Quiz 13: Head pattern variations 

      March 2, 2012

      Here are four more birds with questions about their head feathers. With thanks, again, to Brian E. Small for providing the beautiful photos. You can see…

    • Quiz 12: More on head feathers 

      February 29, 2012

      A teaser of spring wood-warblers on this bonus day of February. Two questions for each of the photos will help you practice applying your knowledge of head…

    • Introduction to breast feathers 

      February 28, 2012

      One of the well-defined groups of feathers on the underside of a bird is what we call the breast. In reality, on songbirds these feathers grow from the…

    • Rare birds "under the radar" 

      February 24, 2012

      In previous posts here I've asked "How many rare birds do we miss?" and the related question "How many rare birds do we find?" Several recent rare bird…

    • Quiz 11: Head feather groups and simple color patterns 

      February 22, 2012

      This quiz is about taking the feather groups you've learned in previous quizzes, and applying them to real birds, to see how color patterns follow the basic…

    • Quiz 10: Head feathers - without markings 

      February 21, 2012

      This quiz features a Dark-eyed Junco, a species with no discernible color pattern on the head. How can you distinguish groups of head feathers with no color…

    • Quiz 9: More on Head feathers 

      February 20, 2012

      Here is a close-up of the head of a Song Sparrow, showing the feather groups and feather markings really well. In the copy below, I've outlined the feather…

    • Quiz 8: Introduction to head feathers 

      February 16, 2012

      Color patterns on the heads of birds are some of the most complex, and also some of the most important for identification. Understanding those patterns is…

    • Quiz 7: more on bird weights, with a twist 

      February 15, 2012

      In this quiz your challenge is to compare the weight of the birds with common household items. There is variation in the weight of the birds, and variation in…

    • It's right where I'm looking! 

      February 14, 2012

      or: How to point out the location of a bird Discussions of birding techniques dwell mainly on finding and identifying birds, as they should, but as soon as…

    • Quiz 6: Bird weight 

      February 13, 2012

      Below is a chance to test your knowledge of bird size, by selecting the heavier species in each of five pairs of birds. Weight, or apparent bulk, is one of the…

    • Quiz on Bird Topography: Wings 3 

      February 10, 2012

      Each label in the photo above points to a feather group associated with the wings. In the quiz below, choose the correct name for that labeled feather…

    • Quiz on Bird Topography: Wings 2 

      February 8, 2012

      Identify the two labeled feather groups in the quiz below, with a couple of bonus questions.

    • A quiz on bird wing feathers 

      February 7, 2012

      The major groups of feathers on the wing are showing well on this American Robin, and each is labeled with a letter. In the quiz below, select the letter…

    • The two stages of field identification 

      January 30, 2012

      As I work on the revision of my field guide I've been giving a lot of thought to how the book can assist the process of identification, and what information is…

    • Do "dwarf" birds exist? 

      January 13, 2012

      A recent discussion on the ID-Frontiers listserver involved an immature gull photographed in Utah (photo by Norman Jenson here). The consensus (and I agree) is…

    • Overconfidence 

      October 27, 2011

      A recent article by Tim Enthoven in the New York Times - Don’t Blink! The Hazards of Confidence - offers some fascinating thoughts on judgment, expertise,…

    • The finer points of wing translucence  

      August 15, 2011

      Patterns of translucence in wing feathers provide useful identification clues for many species of birds - terns, gulls, hawks, and others. Generally the…

    • Abnormal coloration in birds: Melanin reduction  

      August 5, 2011

      Albino and partial albino birds The presence of white feathers on a normally dark bird is the most frequently seen color abnormality. Every birder can…

    • More on illusions of size 

      July 14, 2011

      This is a follow-up to my recent post about Optical illusions and bird identification. While working on some heron studies the other day, I found a good…

    • Powder down and the Black-crowned Night-Heron  

      June 29, 2011

      In a footnote here I mentioned that blackish feathers can appear gray because of powder down, and now I will offer a little more explanation. Powder…

    • Optical illusions and bird identification 

      June 20, 2011

      Here is a classic optical illusion - the three horizontal lines in the image below are all the same length. Yes, they are identical (move your cursor over the…

    • The Proper Use of Playback in Birding  

      April 7, 2011

      A Korean translation of this post is here With the recent surge in the availability of digital audio devices, the use of playback to attract birds into view…

    • Subspecies by phenology - Great Blue Heron 

      March 3, 2010

      Phenology is the study of the timing of natural events, and I have recently begun to realize how useful it is for distinguishing subspecies of birds. In San…

    • Kingbirds, nightjars, and the perception of bird sounds 

      December 10, 2009

      In a recent post on his excellent blog Earbirding, Nathan Pieplow points out an issue with the voice description of Buff-collared Nightjar in the Sibley…

    • Variation in immature Ring-billed Gulls 

      December 1, 2009

      On October 9th, 2005 I was enjoying the view at First Encounter Beach in Eastham, Massachusetts and watching a small flight of seabirds. A flock of gulls began…

    • Ageing Canada Geese 

      October 20, 2009

      Determining the age of a goose can be helpful for identification, and can also reveal some interesting behavioral and ecological information by enabling you to…

    • Probability in bird identification 

      October 1, 2009

      One of my regular birding spots is a small farm field near my house in Concord, Massachusetts. I can walk around the entire place in about 20 minutes, but I…

    • How many rare birds did we miss before the internet? 

      November 15, 2008

      Yesterday morning I 'found' Canada's first Lucy's Warbler... in my inbox. After reading my recent posts about rare birds, Cathy Mountain (whose redpoll…

    • So how many do we find? 

      November 6, 2008

      My last post "How many rare birds do we miss?", was simply getting at the idea that we can miss something glaringly obvious if we are not looking for it. A…

    • How many rare birds do we miss? 

      October 21, 2008

      As birders we often talk about the problem of common birds being misidentified as rare ones. The counterpoint, but probably more frequent, is that rare birds…

    • Audubon's mysteries: Carbonated Swamp-Warbler 

      March 28, 2008

      One of the enduring mysteries of North American ornithology involves several species which were painted by Audubon in the early 1800s but never seen again. The…

    • Redpoll investigation widens to include "Greater" 

      March 7, 2008

      Maybe we are just more aware and looking harder for "Greater" Common Redpolls (Carduelis flammea rostrata) this winter in Massachusetts, or maybe it's really…

    • Urging caution when identifying Common Redpolls 

      January 14, 2008

      Redpoll identification is challenging because Hoary and Common Redpoll seem to show an unbroken continuum of variation from pale to dark, and there are no…

    • Perspective on a mystery bird 

      December 6, 2007

      Our perspective and the assumptions and decisions that are triggered by that point-of-view, strongly influence how we perceive the world around us. In short,…

    • Certainty in sight records 

      October 30, 2007

      In late August 1982 I walked into the weedy fields at the South Cape May Meadows in search of rare birds. Among many species that I had in mind as possible…

    • Fitting pegs in holes 

      September 17, 2007

      I've thought more about the "square-peg-in-round-hole" analogy in my previous post, and made a few simple drawings to expand that analogy. In many ways, bird…

    • Ambiguity and bird identification 

      September 15, 2007

      Last week I had the pleasure of spending four days birding at Barrow, Alaska, working on an eider identification project with the US Fish and Wildlife Service.…

    • Judging size of birds 

      August 29, 2007

      Size judgment is one of the constant quandaries of bird identification - critically important but fraught with error. In a recent online discussion about these…

  • events  (13)
    • In search of Spoon-billed Sandpiper 

      September 11, 2012

      Join me on a WINGS/Heritage Expeditions cruise 21 June to 4 July 2013 to search for nesting Spoon-billed Sandpipers in Siberia. I’ve always been fascinated…

    • Upcoming event: March 3rd in Massachusetts 

      February 23, 2012

      I'll be at MassAudubon's annual Birders Meeting next Saturday, March 3rd, in Waltham, Massachusetts. Directions and more info is here. The theme is…

    • Want to go birding in Montana in May-June? 

      January 12, 2012

      There are still a few places left on my 2012 birding workshops 27 May to 8 June 2012 at Pine Butte Guest Ranch in Montana. It's a great opportunity to visit a…

    • Two new events coming up this month 

      May 5, 2011

      11 May 2011, 6:00 to 8:30 PM - Lecture at Boston Public Library, Boston, MA Sponsored by the New England Forestry Foundation. I'll be talking about the…

    • A chance to own an original painting of Spoon-billed Sandpiper 

      April 13, 2010

      I've donated this original painting of Spoon-billed Sandpiper which is being given away over at 10000 Birds. In order to have a chance to win it all you have…

    • Upcoming Events - March 2010 

      March 5, 2010

      I have updated my events page with several public events in the next few weeks, including a live radio show with Ken Gale on Tuesday March 9th at 11 AM on…

    • Big Day, and Blogging hiatus 

      May 6, 2008

      Upcoming events: I'll be out on a fossil-fuel-free big day this coming weekend, bicycling around Concord, Massachusetts (hoping for 100 species) and I'll try…

    • Upcoming events in early 2008 

      January 31, 2008

      Feb 24 - I'll be speaking at the Northwest Branch of the Corpus Christi Public Library on February 24th at 4 PM to help celebrate the opening of their new Clif…

    • Calendars and columns 

      December 6, 2007

      I was in Washington DC recently and signed some calendars at my cousin's flower shop in Mount Airy, Maryland. So if you've been thinking about getting a…

    • My new Birder's World column 

      November 15, 2007

      I'm pleased to join my friends Kenn Kaufmann, Pete Dunne and others as a contributor to Birder's World magazine, and editor Chuck Hagner promises that I will…

    • Paintings on exhibit 

      November 14, 2007

      Six original plates from the Sibley Guide to Birds will be exhibited at the Cahoon Museum of American Art in Cotuit, MA now through December 31, 2007 as part…

    • Two upcoming events 

      September 5, 2007

      On Thursday, 27 Sep 2007, I'll be in New Haven, Connecticut lecturing at Yale's Peabody Museum (where I spent many afternoons as a teenager in the 1970s) as…

    • Interviews 

      October 27, 2004

      North Country Public Radio - October 10, 2003 David Sibley led a group of North Country birders along Clarkson University’s nature trails last fall. Martha…

  • conservation  (20)
    • Hummingbird Art Auction to benefit Paton's Birder Haven 

      October 7, 2013

      Auction closed with a winning bid of 60! Thanks to everyone for your support. And you can still make a donation at the ABC website here. Like so many…

    • Rough-legged vs. Red-tailed? 

      February 21, 2012

      The other morning I was passing a farm field near my house. It's a place where I often go birding and as I glanced around I was thinking "maybe there could…

    • Thailand Sandpiper Info Center - Grand Opening 

      June 25, 2011

      Thanks to all who donated (and to Audubon California for facilitating), the Sandpiper Information Center at Pak Thale is ready for its grand opening on 26…

    • New efforts to save Spoon-billed Sandpiper 

      June 7, 2011

      There is more evidence of the dire situation with Spoon-billed Sandpiper – efforts are currently underway to develop a captive-breeding population. A…

    • Salt pans and sandpipers 

      February 1, 2011

      The benefit auction concluded in Feb 2011 (more information in a post here) is all about protecting salt pans in Thailand that are critical wintering…

    • Donate to help Spoon-billed Sandpiper  

      January 20, 2011

      The painting shown here is currently available at auction (see box at right, revised on 24 Jan) with 100% of the proceeds going to support the efforts of…

    • Birding and a warming arctic 

      September 1, 2010

      Up until the 1980s, permanent sea ice north of Canada and Russia would have been a substantial barrier to the movement of birds around the Arctic Ocean,…

    • New York Times on windows and birds 

      August 31, 2010

      An article in the Aug 28, 2010 edition of the New York Times - Warning to Birds: All-Glass Buildings Ahead - describes recent developments in window…

    • Why is Spoon-billed Sandpiper disappearing? 

      February 24, 2010

      Spoon-billed Sandpiper populations have been declining for decades, but the reasons are still unclear. Update September 2010 - My conclusion below is that…

    • More on Texas Border Wall 

      April 10, 2008

      Prompted by some good discussion I've read on TexBirds and elsewhere: I want to stress the point that the danger to birds is not so much the height of the…

    • Border Fence puts Texas birds and birding at risk 

      April 7, 2008

      Revised 8 Apr 2008 -Do something: Write or call Congress. See the No Texas Border Wall campaign and their suggestions for action with several petitions to sign…

    • Audubon's mysteries: Carbonated Swamp-Warbler 

      March 28, 2008

      One of the enduring mysteries of North American ornithology involves several species which were painted by Audubon in the early 1800s but never seen again. The…

    • A reprieve for Red Knots 

      March 26, 2008

      Great news: New Jersey's governor Corzine yesterday signed into law a moratorium on the harvest of Horseshoe Crabs in that state (press release here). This is…

    • The Red Knot's troubles 

      March 5, 2008

      The decline of Red Knots from 1982 to 2006:data from Niles et al. 2007. Status of the Red Knot (Calidris canutus rufa) in the Western Hemisphere. USFWS…

    • On conserving migratory birds 

      March 3, 2008

      Taking a break from redpoll identification: I've written an essay about the challenges faced by migrating birds, which appears in this month's Green issue of…

    • More on windows and birds 

      November 20, 2007

      After a week of pretty good success on the windows, today was cold with light snow, and the bird feeder was very active. I realized last week that one of many…

    • A Potential Simple Method for "Bird-Proofing" Windows 

      November 15, 2007

      Update 16 November - There are a couple of points I think I should clarify. First - and I guess this may be clear already - I'm still not convinced this will…

    • Troubled times for Spoon-billed Sandpiper 

      October 13, 2007

      The enigmatic and charismatic Spoon-billed Sandpiper may be headed for extinction according to a Bird Life International report. The population estimate, never…

    • Havel on the environment 

      September 27, 2007

      An Op-Ed in today's New York Times by Vaclav Havel makes reference to the larger issues of consumption and the environment. He minimizes the debate over…

    • sustainability 

      September 18, 2007

      Here's a neat tool from American Public Radio - an educational game that calculates your global ecological footprint.Overconsumption is at the core of…

  • Ivory-billed Woodpecker  (3)
    • Wing twisting explained 

      September 24, 2010

      In discussing the identification of the woodpecker in the Luneau video, my colleagues and I suggested that the extensive white visible in the wings could be…

    • Certainty in sight records 

      October 30, 2007

      In late August 1982 I walked into the weedy fields at the South Cape May Meadows in search of rare birds. Among many species that I had in mind as possible…

    • Ivory-billed Woodpecker - status review 

      October 23, 2007

      In August 2007 the US Fish and Wildlife Service published the Draft Ivory-billed Woodpecker Recovery Plan and invited public comments (the deadline was 22 Oct…

  • events and products  (21)
    • Saw-whet Owl print to benefit research 

      February 21, 2014

      I have made prints of this gouache painting of a Northern Saw-whet Owl from 2006 (more info about my gouache technique here). This painting also appeared in a…

    • Snowy Owl print to benefit Project SNOWstorm 

      January 13, 2014

      I have made prints of this gouache painting that I did in 2011 for the cover of the Journal of Raptor Research to highlight a paper on Snowy Owls (more info…

    • The Second edition is in-hand 

      January 13, 2014

      The completely revised Sibley Guide to Birds, Second Edition, will be on sale in a matter of weeks - March 11, 2014. You can pre-order the second edition at…

    • Book news and gift ideas 

      December 18, 2013

      If you're looking for a one-of-a-kind gift for someone on your list, there are still a couple of days left to order a piece of my original art and have it…

    • Hummingbird Art Auction to benefit Paton's Birder Haven 

      October 7, 2013

      Auction closed with a winning bid of 60! Thanks to everyone for your support. And you can still make a donation at the ABC website here. Like so many…

    • Sibley eGuide for Kindle Fire HD coming within days 

      February 14, 2013

      Some of you had noticed that the Sibley eGuide was not in the Kindle store any more. Apparently the new Kindle Fire HD tablet required changes in the app, but…

    • Updated app for iPhone 

      February 4, 2013

      The Sibley eGuide to Birds app for iPhone has been updated. This update adds thumbnail images of every species in the scrolling list and in search…

    • Announcing my new video guide to bird songs! 

      April 1, 2012

      Update: For future visitors I should explain that I posted this as an April Fool's Joke. This video converts the voice descriptions from the Sibley Guide to…

    • The Sibley eGuide is now available for Blackberry Playbook 

      March 29, 2012

      Just released and available for download at the Blackberry App World - The Sibley eGuide can now be used on any Blackberry Playbook tablet. All of the features…

    • Sibley eGuide for Windows Phone 7 - now available 

      March 7, 2012

      Just released and available for download at the Windows Phone Marketplace - The Sibley eGuide can now be used on any device running Windows Phone 7. All of the…

    • News about the eGuide to Birds 

      February 27, 2012

      I'm happy to report some news about the Sibley eGuide to birds: The price of the app in all versions has been reduced 30% to .99, and a new Lite…

    • Upcoming event: March 3rd in Massachusetts 

      February 23, 2012

      I'll be at MassAudubon's annual Birders Meeting next Saturday, March 3rd, in Waltham, Massachusetts. Directions and more info is here. The theme is…

    • Sibley Flashcards of Common Birds - on sale Feb 7 

      January 24, 2012

      The sturdy box contains one hundred cards, each showing one species of commonly seen bird on the front, with details of habits, identification, and range…

    • Sibley eGuide available for Kindle Fire 

      January 20, 2012

      The Sibley eGuide to birds was recently adapted for the Kindle Fire tablet (and still works on other Android OS devices). You can find it at the Amazon app…

    • New Raptors poster and other gift ideas 

      December 7, 2011

      New from Scott & Nix - Sibley's Raptors of North America poster List price .95 24 x 36" Buy from Amazon Buy from Scott & Nix, framed…

    • The eGuide for Blackberry is available! 

      May 10, 2011

      At last....  The Sibley eGuide is now available for Blackberry! Check it out at the Blackberry App Store Now Blackberry owners can enjoy having the…

    • Two new events coming up this month 

      May 5, 2011

      11 May 2011, 6:00 to 8:30 PM - Lecture at Boston Public Library, Boston, MA Sponsored by the New England Forestry Foundation. I'll be talking about the…

    • Product News 

      November 18, 2010

      Posters Several new posters have been released by Scott & Nix, including Backyard Birds of the West, Waterfowl, Hummingbirds, Owls, and Raptors of North…

    • Android eGuide now available! 

      November 11, 2010

      Android eGuide now available! The Sibley eGuide is now available in the Android market. Some info is here. Please let me know of any concerns, questions,…

    • Tree Guide news 

      September 22, 2009

      Two events related to The Sibley Guide to Trees: It is the featured product today on the Daily Grommet website. I’ll be checking in periodically, responding…

    • My latest project 

      September 10, 2009

      After seven years of work, my new Guide to Trees goes on sale officially on September 15th (but those who live near Philadelphia can get it as early as…

  • Bird-window collisions  (5)
    • New York Times on windows and birds 

      August 31, 2010

      An article in the Aug 28, 2010 edition of the New York Times - Warning to Birds: All-Glass Buildings Ahead - describes recent developments in window…

    • Promising new window film may prevent bird collisions 

      June 24, 2009

      The most recent research by Dr. Daniel Klem, who has been studying the problem of bird/window collisions since the 1990s, has just been published in the June…

    • More Bird-friendly Window Treatments 

      January 7, 2008

      Just a quick update on my window-collisions research:I've heard from several more people who have tried the highlighter with pretty good success.Continuing my…

    • More on windows and birds 

      November 20, 2007

      After a week of pretty good success on the windows, today was cold with light snow, and the bird feeder was very active. I realized last week that one of many…

    • A Potential Simple Method for "Bird-Proofing" Windows 

      November 15, 2007

      Update 16 November - There are a couple of points I think I should clarify. First - and I guess this may be clear already - I'm still not convinced this will…

  • Bird songs  (15)
    • Understanding Alarm Calls of Birds 

      May 27, 2012

      Among the many benefits of paying attention to bird sounds is that they give you an insight into what the birds are doing. Through their songs and calls the…

    • Bird Song ID series continues - Eastern Trills 

      May 18, 2012

      The next part of my introduction to learning bird songs is now up (click here). Birds can hear a lot “faster” than we can, however, and consequentl…

    • Bird songs Part 5: Describing Quality 

      May 14, 2012

      Part 5 of my introduction to learning bird songs is now up (click here). Many of the words that we use to describe the quality of a bird song also…

    • Part 4: Understanding Quality in bird song 

      May 11, 2012

      Part 4 of my introduction to learning bird songs is now up (click here). In the narrowest sense, the quality of a bird’s voice would refer strictly…

    • Tempo, and bird song identification 

      May 8, 2012

      Part 3 of my introduction to learning bird songs is now up (click here). In this discussion, tempo refers to the overall “pace” of the song, the…

    • Pitch, and bird song identification 

      May 4, 2012

      Pitch is simply our perception of the frequency (or wavelength) of a sound, which we describe as high to low. Birds’ range of hearing is similar to our own,…

    • Mystery Bird Song - Concord, MA 

      April 29, 2012

      I recorded this sound (with my iPhone, please excuse the poor quality) on 29 April 2012 near my house in Concord, MA. Have a listen and see what you think. For…

    • Does Blackpoll Warbler have song dialects? 

      July 1, 2011

      I've been aware of some variation in songs of Blackpoll Warbler for many years, and now an interesting post by Andrew Spencer at Earbirding prompted me to…

    • A Mystery Sound 

      June 24, 2011

      23 Jun 2011 – Concord, MA Sitting at my desk today I was roused by a bird call that I did not immediately recognize. This is a very rare occurrence for me,…

    • The Proper Use of Playback in Birding  

      April 7, 2011

      A Korean translation of this post is here With the recent surge in the availability of digital audio devices, the use of playback to attract birds into view…

    • Vocal copying by American Robin  

      April 5, 2011

      On 5 April 2011 in Concord Massachusetts I was walking the edge of a field where I often go birding, and heard very distinctly the sputtering call of an…

    • You too can record and identify Crossbill call types 

      October 5, 2010

      If you've followed any of the discussions about identifying Red Crossbill call types, you may have given up on taking an active role in crossbill study,…

    • Kingbirds, nightjars, and the perception of bird sounds 

      December 10, 2009

      In a recent post on his excellent blog Earbirding, Nathan Pieplow points out an issue with the voice description of Buff-collared Nightjar in the Sibley…

    • More vocal copying by American Goldfinch, Purple Finch, and Ovenbird 

      July 9, 2009

      After listening carefully to Pine Siskins this year to pick out the calls of other species (see my earlier post) I have run across several other mimics. In…

    • Vocal copying by Pine Siskins 

      May 13, 2009

      In July 1990 I spent several weeks birding in west-central British Columbia, where Pine Siskins were one of the most conspicuous birds, and I became convinced…

  • Tree Guide updates  (5)
    • Variation in shape of Hickory nuts 

      November 30, 2009

      Thanks to an email from Ray Telfair I've taken a closer look at the illustrations and descriptions of hickory nuts on pages 143 to 149 in the Guide to…

    • A modern (holistic) approach to Tree Identification 

      November 10, 2009

      Through this fall I've been talking about what I tried to accomplish in my new Guide to Trees. In essence, I tried to approach tree identification in the same…

    • Corrections to The Sibley Guide to Trees 

      October 14, 2009

      Here are page-by-page corrections and changes for The Sibley Guide to Trees. This listing will be updated periodically as issues come to my attention.…

    • Correction to maples, page 332 

      September 23, 2009

      Reader Sherman Dunnam sent me a note about an error in the introduction to maples on page 332. The third paragraph begins "All maples have palmately compound…

    • Updates to the Tree Guide 

      September 23, 2009

      I have spent the last seven years working intensively on my new Guide to Trees, but of course a few misstatements and errors somehow managed to creep in. I'm…

  • Books  (15)
    • The Second edition is in-hand 

      January 13, 2014

      The completely revised Sibley Guide to Birds, Second Edition, will be on sale in a matter of weeks - March 11, 2014. You can pre-order the second edition at…

    • Book news and gift ideas 

      December 18, 2013

      If you're looking for a one-of-a-kind gift for someone on your list, there are still a couple of days left to order a piece of my original art and have it…

    • eGuide update - Redesigned for iPad! 

      December 5, 2011

      The Sibley eGude to Birds for iPhone and iPad has been updated to be a universal app. The new version takes advantage of the full screen of the iPad to show…

    • The eGuide for Blackberry is available! 

      May 10, 2011

      At last....  The Sibley eGuide is now available for Blackberry! Check it out at the Blackberry App Store Now Blackberry owners can enjoy having the…

    • Sibley Guide in action - Redpoll Identification 

      April 1, 2011

      Not an April Fool's joke, this is a real photo taken today by Scott Young in New Hampshire (Thanks, Scott). Clicking the photo links to his Flickr site where…

    • Birding Basics - Now in Spanish! 

      July 24, 2010

      The book Sibley's Birding Basics has been translated into Spanish. More details and ordering info can be found at the Corbidi website (also in Spanish).

    • Updates to the Sibley eGuide to Birds of North America 

      June 11, 2010

      The eGuide for iPhone was recently updated with all new high-resolution images which can now be displayed full screen; a cleaner and simpler navigation…

    • New Folding Guides to birds 

      March 31, 2010

      The Sibley Guide to Birds is now available in a series of eight laminated "folding guides" to birds. They can be found in many book and nature shops for .95…

    • The Sibley eGuide to the Birds of North America 

      February 17, 2010

      Updated June 5th 2010 with high-res images! The Sibley Guide to Birds is now available as an app for iPhone and iPod Touch. Check it out at the iTunes app…

    • Calendars and columns 

      December 6, 2007

      I was in Washington DC recently and signed some calendars at my cousin's flower shop in Mount Airy, Maryland. So if you've been thinking about getting a…

    • New products 

      November 5, 2007

      Responding to some recent questions:A couple of readers have asked about any plans for an updated version of my bird guides. This is something I'm always…

    • Updates and Corrections for the Sibley Western Guide 

      November 6, 2004

      p 143 – Pacific Golden-Plover: on adult male breeding the labels pointing to undertail coverts and flanks are reversed. p. 252 – White-throated Swift:…

    • Updates and Corrections to the Sibley Eastern Field Guide 

      November 6, 2004

      p. 76 – Northern Shoveler text in mid-paragraph says “with with” p 136 – Shorebirds family, parentheses at end of paragraph are unclear. This should…

    • What species are in the Eastern and Western bird guides? 

      October 27, 2004

      The Eastern and Western Guides were carefully planned to avoid dividing states. The Rocky Mountains form a natural biological and climatic division of the…

    • Which bird book should I buy? 

      October 27, 2004

      The Sibley Guide to Birds Focus: bird identification Region covered: North America north of Mexico Species covered: 810 The Sibley Guide to…

  • Bird hybrids  (6)
    • Another odd Snowy Egret, or a hybrid? 

      May 22, 2013

      Recently on Cape Cod, Massachusetts, Mary Keleher noticed an egret with two long head plumes, and took a couple of photos. This bird matches well with the ones…

    • An apparent hybrid Yellow-billed x Common Loon  

      June 22, 2011

      On 9 Jun 1987 I was leading a WINGS tour group at Churchill, Manitoba, and we chartered a small boat to go out on the river for an hour or so to see Belugas…

    • Possible hybrid sandpiper in Kenya 

      January 10, 2011

      In December 2010 I had the privilege of birding in Kenya with the incomparable Brian Finch, and on 14 December we stumbled upon an interesting small sandpiper…

    • A second odd sandpiper from Thailand 

      February 24, 2010

      I recently posted about an apparent hybrid sandpiper in Thailand. A few days earlier on the same trip (7 Feb 2010) I had seen another odd sandpiper that didn't…

    • An apparent hybrid sandpiper in Thailand 

      February 23, 2010

      On 14 Feb, 2010, while watching Spoon-billed Sandpipers at Pak Thale, Thailand, I observed a small sandpiper that did not fit any known species. I assume it is…

    • Parula Hybrids? 

      January 3, 2008

      I have had two inquiries about Tropical Parula in the last 24 hours, prompted by a bird currently in Austin, Texas. You can check out that bird in photos by…

  • art  (17)
    • Saw-whet Owl print to benefit research 

      February 21, 2014

      I have made prints of this gouache painting of a Northern Saw-whet Owl from 2006 (more info about my gouache technique here). This painting also appeared in a…

    • Snowy Owl print to benefit Project SNOWstorm 

      January 13, 2014

      I have made prints of this gouache painting that I did in 2011 for the cover of the Journal of Raptor Research to highlight a paper on Snowy Owls (more info…

    • Hummingbird Art Auction to benefit Paton's Birder Haven 

      October 7, 2013

      Auction closed with a winning bid of 60! Thanks to everyone for your support. And you can still make a donation at the ABC website here. Like so many…

    • My Pen-and-ink technique 

      September 17, 2012

      With the publication of the revised edition of Hawks in Flight, I wanted to post a little bit about my drawing technique with pen and ink. I've…

    • The joy of finger-painting 

      June 11, 2012

      The painting featured here was done during my recent birding workshop at the Pine Butte Guest Ranch in Montana, and is being auctioned to support the great…

    • Auction of original art closing soon 

      June 3, 2012

      The auction for this painting will be closing in about 48 hours - at 9 PM Eastern time on Tuesday June 5th. You can see the auction and closing time in the…

    • New art for auction 

      May 28, 2012

      I've just posted a new painting for auction. You can see the auction and closing time in the sidebar to the right. This is a small gouache painting of a…

    • Auction of my Original Art - Closing Tomorrow (Sunday) 

      April 14, 2012

      I am now offering two of my drawings in an auction, which will be closing in about 24 hours – at 6PM Eastern Time on Sunday April 15th. The two…

    • Upcoming event: March 3rd in Massachusetts 

      February 23, 2012

      I'll be at MassAudubon's annual Birders Meeting next Saturday, March 3rd, in Waltham, Massachusetts. Directions and more info is here. The theme is…

    • Painting a Saw-whet Owl 

      February 8, 2012

      Yesterday I painted a Northern Saw-whet Owl of the very distinctive Queen Charlotte Islands subspecies A. a. brooksi, which was inexplicably left out of the…

    • New Art for Sale - August 

      August 10, 2011

      I've just updated the New Art page, adding a few paintings that I've completed in the past month, including the Pileated Woodpecker shown here. Thanks for…

    • Osprey painting at auction 

      July 20, 2011

      I have donated the painting shown at right – an Osprey carrying a small Striped Bass – to The Nature Conservancy's Mashomack Preserve on Shelter…

    • Now accepting commissions for new art 

      July 13, 2011

      An opportunity to own an original painting of your favorite bird With a little spare time between book contracts, I have decided to take on a limited number…

    • Ink on scratchboard technique 

      February 11, 2011

      In a recent comment on the Art Gallery page, Rawlings asked about my use of scratchboard as a medium. I’ve done a lot of work in ink on scratchboard, and…

    • Original Sibley Art for Sale 

      October 19, 2010

      A selection of my original art is now available for sale at this page. The pieces offered include gouache portraits of birds, many of which were printed in a…

    • My painting process – gouache 

      January 13, 2010

      In 2004 I was working on a small painting of a flying Ferruginous Hawk, and I scanned the work at several stages to show the progression from pencil sketch to…

    • Prints for sale 

      November 2, 2004

      Black-and-white prints from “The Wind Masters” Osprey print is sold out. This set of four prints is taken from artwork originally published in The Wind…

  • Bird subspecies  (31)
    • Peter Pyle on Sage Sparrows 

      August 20, 2013

      The most significant change for North American birders in the 2013 AOU Checklist supplement is the split of Sage Sparrow into two species: Sagebrush Sparrow…

    • An unusual Cattle Egret in Florida  

      May 22, 2012

      In late April 2012, Roy Halpin found and photographed an entirely buff-colored Cattle Egret in Saint Augustine, Florida. This is a particularly interesting…

    • Variation in immature American Herring Gulls 

      February 3, 2012

      A recent discussion about geographic variation in Herring Gulls (on the ID-Frontiers listserve) prompted me to go back and scan some photos I took in 1998 at…

    • A Wurdemann's-like heron from South Florida 

      January 25, 2012

      Thanks to reader Anne DuPont for sending in these photos of a pair of Great Blue Herons at Wakodahatchee Wetlands, Delray Beach, Florida. It's clearly a mated…

    • Subspecies of Scaled Quail 

      January 17, 2012

      There are four named subspecies of Scaled Quail, three in the US and one in Mexico. The subspecies found in southern Texas is distinctly different from the…

    • Distinguishing Eurasian and American Common Merganser 

      July 29, 2011

      The Eurasian subspecies group of Common Merganser, known by the English name Goosander, has occurred numerous times in the Aleutian Islands of western Alaska,…

    • The mysterious dark Least Bittern 

      July 23, 2011

      Dark morph (Cory's) Least Bittern Note: I have never personally seen a living Cory's Least Bittern. In fact, only six or so have been seen during my lifetime.…

    • The Newfoundland Moorhen was an American based on back color 

      July 19, 2011

      Last winter's Common Moorhen in Newfoundland, given the likely split of New World and Old World moorhens into separate species, led me to try to determine the…

    • Does Blackpoll Warbler have song dialects? 

      July 1, 2011

      I've been aware of some variation in songs of Blackpoll Warbler for many years, and now an interesting post by Andrew Spencer at Earbirding prompted me to…

    • Distinguishing Interior West from Western Taiga White-crowned Sparrows 

      May 20, 2011

      See my detailed discussion of White-crowned subspecies here, which needs updating with the information below. In early May 2011 I spent several days in…

    • Intergradation between Mexican Duck and Mallard in Arizona 

      May 6, 2011

      The Mexican Duck was formerly considered a species (Anas diazi), and is currently lumped with Mallard (as subspecies Anas platyrhynchos diazi), but recent DNA…

    • Three interesting Brant from Massachusetts 

      April 12, 2011

      Note: I'm preparing posts on the range and identification of Brant subspecies, which will help make the following more understandable to those who are not…

    • Identifying subspecies by behavior - Savannah Sparrow 

      March 28, 2011

      Identifying subspecies adds richness to your birding by adding another layer of understanding. What’s more, during spring migration, behavior can offer a…

    • Distinguishing Green-winged and Common Teal 

      March 26, 2011

      The Green-winged Teal (known as Common Teal in English-speaking parts of Eurasia) is currently considered a single species by the AOU, but two subspecies are…

    • Distribution of Greater White-fronted Goose subspecies 

      March 24, 2011

      The Greater White-fronted Goose (Anser albifrons) occurs throughout much of North America, but is found in largely disjunct populations. Only two North…

    • About the List of Field Identifiable Subspecies  

      March 23, 2011

      Click here for the complete list of identifiable subspecies of North American birds Some background on subspecies Subspecies are a common focus of debate…

    • Distinguishing the subspecies of Purple Finch  

      March 22, 2011

      Summary The two subspecies of Purple Finch are fairly distinctive with well-defined ranges. They are best distinguished by overall impression of…

    • Can subspecies of Mountain Chickadee be identified in the field?  

      March 22, 2011

      Not really. Only under ideal conditions and with reference to location. Mountain Chickadee is found throughout much of the montane coniferous forest…

    • The 'Caribbean' Coot in North America 

      March 15, 2011

      Caribbean Coot Fulica caribaea (found sparingly and locally in the West Indies from Hispaniola south and east to the coast of Venezuela) is virtually…

    • Four redpoll taxa in one photo  

      February 22, 2011

      Michael Butler of Marathon, Ontario sent me the remarkable photo below, showing all four taxa of redpolls (four subspecies, two species) in one view (see more…

    • The next 10 North American bird splits 

      April 16, 2010

      A favorite activity among avid birders is speculating and pontificating about which species should be "split" into new species (and new checkmarks on the…

    • Identification of Belding's Savannah Sparrow 

      May 14, 2009

      In early March 2009 it was my pleasure to spend a few days in California at the San Diego Bird Festival. On my first morning in San Diego I headed straight out…

    • More on identification of Greenland White-fronts 

      November 24, 2008

      Coincidentally, just days after my last post about the two White-fronted Geese in Concord, two White-fronted Geese showed up in Amherst, Massachusetts (about…

    • Identification tips for Greenland Greater White-fronted Goose 

      November 21, 2008

      The Greenland Greater White-fronted Goose (Anser frontalis flavirostris) is known to be a rare visitor to northeastern North America, but I have never been…

    • Lesser Canada Goose in the northeastern US 

      November 17, 2008

      The primary challenge of distinguishing Canada from Cackling Goose centers on the intermediate-sized 'Lesser' Canada Goose, B. c. parvipes, which reportedly…

    • Variation in Wild Turkey 

      April 2, 2008

      Here's an example of one of the countless thousands of questions that are still out there waiting to be answered about North American birds. I went to Texas in…

    • Greater Redpoll photos 

      March 11, 2008

      Maybe I should change the name of this blog to "All about Redpolls", but I've received a few photos that I wanted to pass along, making the point that…

    • Another large pale redpoll 

      March 10, 2008

      A new photo by Dan Berard shows what looks like an intermediate large redpoll, and should be added to the discussion in my previous post.photo copyright Dan…

    • Redpoll investigation widens to include "Greater" 

      March 7, 2008

      Maybe we are just more aware and looking harder for "Greater" Common Redpolls (Carduelis flammea rostrata) this winter in Massachusetts, or maybe it's really…

    • Redpoll subspecies 

      December 4, 2007

      If identifying Hoary Redpoll is not enough of a challenge for you, maybe you'd like to look for subspecies of Hoary and Common Redpolls? First, check out…

    • "Great White" Heron - not just a color morph 

      November 5, 2007

      Great White Heron Ardea herodias occidentalis updated 13 Nov 2007, thanks to all those who have commented publicly and privately. I've backed off a bit from…

  • Bird topography  (38)
    • Quiz on Belizean Birds and Greater Coverts 

      February 20, 2014

      Find the Greater Secondary Coverts These are some of my digiscoped photos from a recent trip to Belize, all taken at the fantastic Black Rock Lodge. On…

    • Quiz 54: Head patterns 

      January 2, 2013

      The three photos below show a Song Sparrow as it turns its head. Your challenge is to locate the plumage marking known as the lateral throat stripe in each…

    • Quiz 50: Bird topography - upperside 

      September 5, 2012

      Here is a new quiz about the topography of the upperparts of a large songbird.

    • Quiz 42: More topography of the upperparts 

      July 24, 2012

      Here is another quiz showing a bird viewed from behind, with questions about the feather groups that are visible. Notice how the contours of the back define…

    • Quiz 40: Feather topography of the upperparts 

      July 18, 2012

    • Quiz 38: More feathers, and a prize 

      May 24, 2012

      Today's quiz features a bonus And we have a winner - Congratulations to Nicholas! Thanks to all who entered. Watch for another quiz giveaway in the near…

    • Quiz 37: Bird topography 

      May 23, 2012

      Test your knowledge of bird feather topography with the questions below.

    • Bird Topography - How it helps identify birds 

      April 16, 2012

      I was musing on the value of learning bird topography this morning, wondering why it is so important to know the greater coverts and supercilium and all the…

    • Quiz 28: More Warblers 

      April 13, 2012

      Update: Congratulations to Vjera, the winner of this week's prize drawing! Thanks to all who entered. Watch for another giveaway next week. The quiz prize…

    • Quiz 27: More Warblers and Color Patterns 

      April 11, 2012

      This week's quizzes are looking at some warblers, in anticipation of the spring migration (which is already in full swing in some parts of the country). With…

    • Quiz 26: Warblers and head patterns 

      April 10, 2012

      This week's quizzes will be looking at some warblers, in anticipation of the spring migration. With thanks, again, to Brian E. Small for providing the…

    • Quiz 25: Wing patterns 

      April 6, 2012

      Update: Congratulations to Alvan, the winner of the Backyard Birds poster. Thanks to all who took the quiz and entered. The response was fantastic, and keep…

    • Quiz 24: Wing Patterns 

      April 5, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 23: Wing patterns 

      April 4, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 22: Wing patterns 

      April 3, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Identification of female bluebirds by wing structure 

      March 27, 2012

      A pale and grayish female bluebird found in North Carolina recently (March 2012) provided a very interesting identification challenge. The plumage colors were…

    • Quiz 20: Wings, long and narrow 

      March 15, 2012

      This quiz groups some relatively long and narrow wings. Pay special attention to subtle differences in shape, and bold white patterns. With thanks to the…

    • All wings are the same, in some ways 

      March 13, 2012

      Here is a quiz with three very different wings, and a detailed explanation follows (don't peek). With thanks to the online wing collection of the Slater…

    • Wings, above and below  

      March 10, 2012

      Most birds have a very different pattern on the upperside and underside of their wings. On the coverts (the leading edge of the wing) this is easily explained…

    • Quiz 16: Identifying blue wings 

      March 8, 2012

      Wings are amazing. Marvels of engineering, with intricate and changeable color patterns, they offer endless avenues for study. But seeing the details of a wing…

    • A head feather survey 

      March 7, 2012

      Update: 9 March 2012 Thank you! The response to the head feather survey has been fantastic: 95 participants as of 10 AM on March 9th. The survey will be…

    • What is the submoustachial? 

      March 7, 2012

      The feathers along the side of the lower jaw have a very confusing history of terminology. They've been called the malar stripe (in many early and mid 20th…

    • Quiz 15: The submoustachial 

      March 6, 2012

      Regardless of what you call them – submoustachial, malar, jaw stripe, mandibular stripe – the feathers along the side of the lower jaw are important for…

    • Variation in head pattern 

      March 5, 2012

      In recent posts and quizzes here I've been stressing the head feather groups, and how they provide a consistent structure for understanding the color patterns…

    • The changeable shape of the supercilium 

      March 3, 2012

      The feathers that grow on the sides of the head above the eyes of a bird are called the supercilium, and when they contrast in color with the adjacent feathers…

    • Quiz 13: Head pattern variations 

      March 2, 2012

      Here are four more birds with questions about their head feathers. With thanks, again, to Brian E. Small for providing the beautiful photos. You can see…

    • Quiz 12: More on head feathers 

      February 29, 2012

      A teaser of spring wood-warblers on this bonus day of February. Two questions for each of the photos will help you practice applying your knowledge of head…

    • Introduction to breast feathers 

      February 28, 2012

      One of the well-defined groups of feathers on the underside of a bird is what we call the breast. In reality, on songbirds these feathers grow from the…

    • Quiz 11: Head feather groups and simple color patterns 

      February 22, 2012

      This quiz is about taking the feather groups you've learned in previous quizzes, and applying them to real birds, to see how color patterns follow the basic…

    • Quiz 10: Head feathers - without markings 

      February 21, 2012

      This quiz features a Dark-eyed Junco, a species with no discernible color pattern on the head. How can you distinguish groups of head feathers with no color…

    • Quiz 9: More on Head feathers 

      February 20, 2012

      Here is a close-up of the head of a Song Sparrow, showing the feather groups and feather markings really well. In the copy below, I've outlined the feather…

    • Quiz 8: Introduction to head feathers 

      February 16, 2012

      Color patterns on the heads of birds are some of the most complex, and also some of the most important for identification. Understanding those patterns is…

    • Quiz on Bird Topography: Wings 3 

      February 10, 2012

      Each label in the photo above points to a feather group associated with the wings. In the quiz below, choose the correct name for that labeled feather…

    • Quiz on Bird Topography: Wings 2 

      February 8, 2012

      Identify the two labeled feather groups in the quiz below, with a couple of bonus questions.

    • A quiz on bird wing feathers 

      February 7, 2012

      The major groups of feathers on the wing are showing well on this American Robin, and each is labeled with a letter. In the quiz below, select the letter…

    • The finer points of wing translucence  

      August 15, 2011

      Patterns of translucence in wing feathers provide useful identification clues for many species of birds - terns, gulls, hawks, and others. Generally the…

    • Distinguishing Green-winged and Common Teal 

      March 26, 2011

      The Green-winged Teal (known as Common Teal in English-speaking parts of Eurasia) is currently considered a single species by the AOU, but two subspecies are…

    • Sparrows and central spots 

      February 25, 2011

      Can you identify the sparrow shown in this photo? Read on for the discussion and answer below. Thanks to Jerry Tang for the photo and for bringing it to my…

  • Bird behavior  (12)
  • quiz  (56)
    • Quiz on Belizean Birds and Greater Coverts 

      February 20, 2014

      Find the Greater Secondary Coverts These are some of my digiscoped photos from a recent trip to Belize, all taken at the fantastic Black Rock Lodge. On…

    • A video bird quiz 

      February 14, 2013

      The answer is at the end of the video, and in the text below. http://youtu.be/51jRz9crJt4 It has been a relatively mild winter in Massachusetts, but the…

    • Quiz 54: Head patterns 

      January 2, 2013

      The three photos below show a Song Sparrow as it turns its head. Your challenge is to locate the plumage marking known as the lateral throat stripe in each…

    • Quiz 53: Eastern Sparrows in early September 

      September 12, 2012

      Below are three sparrows photographed in Concord, MA on 11 Sep 2012. Can you identify the species? Today's quiz features a bonus Everyone who submits a…

    • Quiz 51: Estimating Numbers 

      September 6, 2012

      Another quiz to test your skill at estimating numbers of birds in flocks.

    • Quiz 50: Bird topography - upperside 

      September 5, 2012

      Here is a new quiz about the topography of the upperparts of a large songbird.

    • Quiz 49: Estimating numbers of birds 

      August 21, 2012

      This time the answers are arranged randomly, instead of sequentially, and I think this makes it a little harder, since it's harder to use the range of possible…

    • Quiz 48: Mystery Bird 

      August 16, 2012

      This bird was photographed in North America, and it's not some exotic vagrant.

    • Quiz 47 - More estimating numbers 

      August 14, 2012

    • Quiz 46 - Estimating numbers 

      August 11, 2012

      Estimating numbers in flocks of birds is a skill that birders need to practice, but we rarely get a chance to test ourselves. We see a flock, guess the total…

    • Quiz 45 - Little Brown Bird Identification 

      August 10, 2012

      No description found for this item.

    • Quiz 44 - Bird flying away 

      August 9, 2012

      No description found for this item.

    • Quiz 43: Still more songbird legs and feet 

      July 26, 2012

      Here are three more songbirds showing some of the variation in legs and feet. With thanks, again, to Brian E. Small for providing the beautiful photos. You…

    • Quiz 42: More topography of the upperparts 

      July 24, 2012

      Here is another quiz showing a bird viewed from behind, with questions about the feather groups that are visible. Notice how the contours of the back define…

    • Quiz 41: More identification by feet 

      July 20, 2012

      More examples of the variety of legs and feet – color and structure – that can be found among the small songbirds. With thanks, again, to Brian E.…

    • Quiz 40: Feather topography of the upperparts 

      July 18, 2012

    • Quiz 39: Bird ID by legs and feet 

      July 16, 2012

      The structure and color of birds' legs is extremely variable. Everyone knows the difference between the webbed foot of a duck and the unwebbed toes of a…

    • Quiz 38: More feathers, and a prize 

      May 24, 2012

      Today's quiz features a bonus And we have a winner - Congratulations to Nicholas! Thanks to all who entered. Watch for another quiz giveaway in the near…

    • Quiz 37: Bird topography 

      May 23, 2012

      Test your knowledge of bird feather topography with the questions below.

    • Trees in their spring colors 

      May 11, 2012

      I've been neglecting trees in my posts recently, but here in Massachusetts spring is the best time of year for tree-watching, and today the sun was out…

    • Quiz 36: More Warblers 

      May 10, 2012

      Today's quiz features a bonus And we have a winner! Congratulations to Laramie, and thanks to everyone who entered! There will be another quiz giveaway…

    • Quiz 35 - More warblers from below 

      May 7, 2012

      Like a previous quiz this one shows warblers as they are so often seen in the field - with just the underside of the body visible. Clues such as tail shape,…

    • Quiz 34 - Brightly-colored Birds 

      May 3, 2012

      Here are five species of intensely colorful spring birds. Can you identify them from just the small parts that are visible? Today's quiz features a…

    • Quiz 33: Small songbirds by their wings 

      May 2, 2012

      This quiz shows just the bodies of five species of small drab songbirds with wingbars. In other quizzes I've given a big clue in the form of telling you the…

    • Quiz 32 - Warblers from below 

      May 1, 2012

      This quiz shows warblers as they are so often seen in the field - with just the underside of the body visible. Clues such as tail shape, overall size,…

    • Mystery Bird Song - Concord, MA 

      April 29, 2012

      I recorded this sound (with my iPhone, please excuse the poor quality) on 29 April 2012 near my house in Concord, MA. Have a listen and see what you think. For…

    • Quiz 31: More warblers by partial cues 

      April 27, 2012

      Here are some partially obscured warblers to test your knowledge. Look especially at the pattern of wingbars to distinguish these three. With thanks,…

    • Quiz 30: Comparing bird weights 

      April 24, 2012

      Continuing the challenge of comparing bird weights, here are some familiar species to test your knowledge.

    • Quiz 29: Comparing bird weights 

      April 23, 2012

      Today's quiz revisits the challenge of comparing bird weights. In the field we get a sense of the "bulk" of a bird, and that is a very important part of…

    • Quiz 28: More Warblers 

      April 13, 2012

      Update: Congratulations to Vjera, the winner of this week's prize drawing! Thanks to all who entered. Watch for another giveaway next week. The quiz prize…

    • Quiz 27: More Warblers and Color Patterns 

      April 11, 2012

      This week's quizzes are looking at some warblers, in anticipation of the spring migration (which is already in full swing in some parts of the country). With…

    • Quiz 26: Warblers and head patterns 

      April 10, 2012

      This week's quizzes will be looking at some warblers, in anticipation of the spring migration. With thanks, again, to Brian E. Small for providing the…

    • Quiz 25: Wing patterns 

      April 6, 2012

      Update: Congratulations to Alvan, the winner of the Backyard Birds poster. Thanks to all who took the quiz and entered. The response was fantastic, and keep…

    • Quiz 24: Wing Patterns 

      April 5, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 23: Wing patterns 

      April 4, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 22: Wing patterns 

      April 3, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 21: Wing patterns 

      April 2, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 20: Wings, long and narrow 

      March 15, 2012

      This quiz groups some relatively long and narrow wings. Pay special attention to subtle differences in shape, and bold white patterns. With thanks to the…

    • Quiz 18: Blue bird parts 

      March 12, 2012

      This quiz shows just parts of three different blue birds. Try to identify the species while seeing only part of the body. With thanks, again, to Brian E.…

    • Quiz 17: Western birds in part 

      March 9, 2012

      Here's a new variation for an ID quiz. Birds in these photos are mostly masked by black. See if you can identify the species without seeing the whole bird. W…

    • Quiz 16: Identifying blue wings 

      March 8, 2012

      Wings are amazing. Marvels of engineering, with intricate and changeable color patterns, they offer endless avenues for study. But seeing the details of a wing…

    • What is the submoustachial? 

      March 7, 2012

      The feathers along the side of the lower jaw have a very confusing history of terminology. They've been called the malar stripe (in many early and mid 20th…

    • Quiz 15: The submoustachial 

      March 6, 2012

      Regardless of what you call them – submoustachial, malar, jaw stripe, mandibular stripe – the feathers along the side of the lower jaw are important for…

    • Quiz 13: Head pattern variations 

      March 2, 2012

      Here are four more birds with questions about their head feathers. With thanks, again, to Brian E. Small for providing the beautiful photos. You can see…

    • Quiz 12: More on head feathers 

      February 29, 2012

      A teaser of spring wood-warblers on this bonus day of February. Two questions for each of the photos will help you practice applying your knowledge of head…

    • Quiz 11: Head feather groups and simple color patterns 

      February 22, 2012

      This quiz is about taking the feather groups you've learned in previous quizzes, and applying them to real birds, to see how color patterns follow the basic…

    • Quiz 10: Head feathers - without markings 

      February 21, 2012

      This quiz features a Dark-eyed Junco, a species with no discernible color pattern on the head. How can you distinguish groups of head feathers with no color…

    • Quiz 9: More on Head feathers 

      February 20, 2012

      Here is a close-up of the head of a Song Sparrow, showing the feather groups and feather markings really well. In the copy below, I've outlined the feather…

    • Quiz 8: Introduction to head feathers 

      February 16, 2012

      Color patterns on the heads of birds are some of the most complex, and also some of the most important for identification. Understanding those patterns is…

    • Quiz 7: more on bird weights, with a twist 

      February 15, 2012

      In this quiz your challenge is to compare the weight of the birds with common household items. There is variation in the weight of the birds, and variation in…

    • Quiz 6: Bird weight 

      February 13, 2012

      Below is a chance to test your knowledge of bird size, by selecting the heavier species in each of five pairs of birds. Weight, or apparent bulk, is one of the…

    • Quiz on Bird Topography: Wings 3 

      February 10, 2012

      Each label in the photo above points to a feather group associated with the wings. In the quiz below, choose the correct name for that labeled feather…

    • Quiz on Bird Topography: Wings 2 

      February 8, 2012

      Identify the two labeled feather groups in the quiz below, with a couple of bonus questions.

    • A quiz on bird wing feathers 

      February 7, 2012

      The major groups of feathers on the wing are showing well on this American Robin, and each is labeled with a letter. In the quiz below, select the letter…

    • Backyard Bird Quiz: part II 

      February 6, 2012

      Here's the next installment in quizzes. I've removed the titles this time so hovering over the image shouldn't give it away (but some browsers will still show…

    • New feature: a bird identification quiz 

      February 1, 2012

      Identify the species shown in each photo by clicking the multiple choice answers. I hope to make short quizzes like this a regular feature of this website, so…

  • Birds abnormal coloration  (5)
    • A Yellow Purple Finch in Ontario 

      July 25, 2012

      Thanks to reader Skip Pothier for sending in these photos. They show a Purple Finch with yellow color instead of red. My first thought was to call it a male…

    • A heron ID quiz 

      July 17, 2012

      Here is a photo of a white heron, taken by Constance Mier on the main shoreline of Biscayne Bay National Park, near Miami, Florida, on May 25, 2012. You…

    • More unusual Cattle Egrets 

      May 28, 2012

      After my post a few days ago about the unusual Cattle Egret in Florida, I heard from two people with interesting observations to add. Robert Edgar and…

    • An unusual Cattle Egret in Florida  

      May 22, 2012

      In late April 2012, Roy Halpin found and photographed an entirely buff-colored Cattle Egret in Saint Augustine, Florida. This is a particularly interesting…

    • The mysterious dark Least Bittern 

      July 23, 2011

      Dark morph (Cory's) Least Bittern Note: I have never personally seen a living Cory's Least Bittern. In fact, only six or so have been seen during my lifetime.…

  • Quiz: bird ID  (37)
    • A video bird quiz 

      February 14, 2013

      The answer is at the end of the video, and in the text below. http://youtu.be/51jRz9crJt4 It has been a relatively mild winter in Massachusetts, but the…

    • Dark heron/egret 

      February 5, 2013

      Can you identify the two birds in this photo? It should be immediately obvious that this photo shows two species of dark herons, and their overall…

    • Quiz 53: Eastern Sparrows in early September 

      September 12, 2012

      Below are three sparrows photographed in Concord, MA on 11 Sep 2012. Can you identify the species? Today's quiz features a bonus Everyone who submits a…

    • Quiz 48: Mystery Bird 

      August 16, 2012

      This bird was photographed in North America, and it's not some exotic vagrant.

    • Quiz 45 - Little Brown Bird Identification 

      August 10, 2012

      No description found for this item.

    • Quiz 44 - Bird flying away 

      August 9, 2012

      No description found for this item.

    • Quiz 43: Still more songbird legs and feet 

      July 26, 2012

      Here are three more songbirds showing some of the variation in legs and feet. With thanks, again, to Brian E. Small for providing the beautiful photos. You…

    • Quiz 41: More identification by feet 

      July 20, 2012

      More examples of the variety of legs and feet – color and structure – that can be found among the small songbirds. With thanks, again, to Brian E.…

    • A heron ID quiz 

      July 17, 2012

      Here is a photo of a white heron, taken by Constance Mier on the main shoreline of Biscayne Bay National Park, near Miami, Florida, on May 25, 2012. You…

    • Quiz 39: Bird ID by legs and feet 

      July 16, 2012

      The structure and color of birds' legs is extremely variable. Everyone knows the difference between the webbed foot of a duck and the unwebbed toes of a…

    • Quiz 38: More feathers, and a prize 

      May 24, 2012

      Today's quiz features a bonus And we have a winner - Congratulations to Nicholas! Thanks to all who entered. Watch for another quiz giveaway in the near…

    • Quiz 36: More Warblers 

      May 10, 2012

      Today's quiz features a bonus And we have a winner! Congratulations to Laramie, and thanks to everyone who entered! There will be another quiz giveaway…

    • Quiz 35 - More warblers from below 

      May 7, 2012

      Like a previous quiz this one shows warblers as they are so often seen in the field - with just the underside of the body visible. Clues such as tail shape,…

    • Quiz 34 - Brightly-colored Birds 

      May 3, 2012

      Here are five species of intensely colorful spring birds. Can you identify them from just the small parts that are visible? Today's quiz features a…

    • Quiz 33: Small songbirds by their wings 

      May 2, 2012

      This quiz shows just the bodies of five species of small drab songbirds with wingbars. In other quizzes I've given a big clue in the form of telling you the…

    • Quiz 32 - Warblers from below 

      May 1, 2012

      This quiz shows warblers as they are so often seen in the field - with just the underside of the body visible. Clues such as tail shape, overall size,…

    • Mystery Bird Song - Concord, MA 

      April 29, 2012

      I recorded this sound (with my iPhone, please excuse the poor quality) on 29 April 2012 near my house in Concord, MA. Have a listen and see what you think. For…

    • Quiz 31: More warblers by partial cues 

      April 27, 2012

      Here are some partially obscured warblers to test your knowledge. Look especially at the pattern of wingbars to distinguish these three. With thanks,…

    • Quiz 30: Comparing bird weights 

      April 24, 2012

      Continuing the challenge of comparing bird weights, here are some familiar species to test your knowledge.

    • Quiz 29: Comparing bird weights 

      April 23, 2012

      Today's quiz revisits the challenge of comparing bird weights. In the field we get a sense of the "bulk" of a bird, and that is a very important part of…

    • Quiz 28: More Warblers 

      April 13, 2012

      Update: Congratulations to Vjera, the winner of this week's prize drawing! Thanks to all who entered. Watch for another giveaway next week. The quiz prize…

    • Quiz 27: More Warblers and Color Patterns 

      April 11, 2012

      This week's quizzes are looking at some warblers, in anticipation of the spring migration (which is already in full swing in some parts of the country). With…

    • Quiz 26: Warblers and head patterns 

      April 10, 2012

      This week's quizzes will be looking at some warblers, in anticipation of the spring migration. With thanks, again, to Brian E. Small for providing the…

    • Quiz 25: Wing patterns 

      April 6, 2012

      Update: Congratulations to Alvan, the winner of the Backyard Birds poster. Thanks to all who took the quiz and entered. The response was fantastic, and keep…

    • Quiz 24: Wing Patterns 

      April 5, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 23: Wing patterns 

      April 4, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 22: Wing patterns 

      April 3, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 21: Wing patterns 

      April 2, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 20: Wings, long and narrow 

      March 15, 2012

      This quiz groups some relatively long and narrow wings. Pay special attention to subtle differences in shape, and bold white patterns. With thanks to the…

    • All wings are the same, in some ways 

      March 13, 2012

      Here is a quiz with three very different wings, and a detailed explanation follows (don't peek). With thanks to the online wing collection of the Slater…

    • Quiz 18: Blue bird parts 

      March 12, 2012

      This quiz shows just parts of three different blue birds. Try to identify the species while seeing only part of the body. With thanks, again, to Brian E.…

    • Off to Belize 

      March 11, 2012

      I'll be away in Belize for the next week or so, leading a trip for Mass Audubon, and in anticipation of that I've posted a photo of one of the most iconic…

    • Quiz 17: Western birds in part 

      March 9, 2012

      Here's a new variation for an ID quiz. Birds in these photos are mostly masked by black. See if you can identify the species without seeing the whole bird. W…

    • Quiz 16: Identifying blue wings 

      March 8, 2012

      Wings are amazing. Marvels of engineering, with intricate and changeable color patterns, they offer endless avenues for study. But seeing the details of a wing…

    • Quiz 6: Bird weight 

      February 13, 2012

      Below is a chance to test your knowledge of bird size, by selecting the heavier species in each of five pairs of birds. Weight, or apparent bulk, is one of the…

    • Backyard Bird Quiz: part II 

      February 6, 2012

      Here's the next installment in quizzes. I've removed the titles this time so hovering over the image shouldn't give it away (but some browsers will still show…

    • New feature: a bird identification quiz 

      February 1, 2012

      Identify the species shown in each photo by clicking the multiple choice answers. I hope to make short quizzes like this a regular feature of this website, so…

  • Quiz: bird topography  (28)
    • Quiz on Belizean Birds and Greater Coverts 

      February 20, 2014

      Find the Greater Secondary Coverts These are some of my digiscoped photos from a recent trip to Belize, all taken at the fantastic Black Rock Lodge. On…

    • Quiz 54: Head patterns 

      January 2, 2013

      The three photos below show a Song Sparrow as it turns its head. Your challenge is to locate the plumage marking known as the lateral throat stripe in each…

    • Quiz 50: Bird topography - upperside 

      September 5, 2012

      Here is a new quiz about the topography of the upperparts of a large songbird.

    • Quiz 42: More topography of the upperparts 

      July 24, 2012

      Here is another quiz showing a bird viewed from behind, with questions about the feather groups that are visible. Notice how the contours of the back define…

    • Quiz 40: Feather topography of the upperparts 

      July 18, 2012

    • Quiz 37: Bird topography 

      May 23, 2012

      Test your knowledge of bird feather topography with the questions below.

    • Quiz 27: More Warblers and Color Patterns 

      April 11, 2012

      This week's quizzes are looking at some warblers, in anticipation of the spring migration (which is already in full swing in some parts of the country). With…

    • Quiz 26: Warblers and head patterns 

      April 10, 2012

      This week's quizzes will be looking at some warblers, in anticipation of the spring migration. With thanks, again, to Brian E. Small for providing the…

    • Quiz 25: Wing patterns 

      April 6, 2012

      Update: Congratulations to Alvan, the winner of the Backyard Birds poster. Thanks to all who took the quiz and entered. The response was fantastic, and keep…

    • Quiz 24: Wing Patterns 

      April 5, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 23: Wing patterns 

      April 4, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 22: Wing patterns 

      April 3, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 21: Wing patterns 

      April 2, 2012

      With thanks to the online wing collection of the Slater Museum of Natural History, University of Puget Sound for allowing the use of their wing photos. With…

    • Quiz 20: Wings, long and narrow 

      March 15, 2012

      This quiz groups some relatively long and narrow wings. Pay special attention to subtle differences in shape, and bold white patterns. With thanks to the…

    • All wings are the same, in some ways 

      March 13, 2012

      Here is a quiz with three very different wings, and a detailed explanation follows (don't peek). With thanks to the online wing collection of the Slater…

    • What is the submoustachial? 

      March 7, 2012

      The feathers along the side of the lower jaw have a very confusing history of terminology. They've been called the malar stripe (in many early and mid 20th…

    • Quiz 15: The submoustachial 

      March 6, 2012

      Regardless of what you call them – submoustachial, malar, jaw stripe, mandibular stripe – the feathers along the side of the lower jaw are important for…

    • Variation in head pattern 

      March 5, 2012

      In recent posts and quizzes here I've been stressing the head feather groups, and how they provide a consistent structure for understanding the color patterns…

    • Quiz 13: Head pattern variations 

      March 2, 2012

      Here are four more birds with questions about their head feathers. With thanks, again, to Brian E. Small for providing the beautiful photos. You can see…

    • Quiz 12: More on head feathers 

      February 29, 2012

      A teaser of spring wood-warblers on this bonus day of February. Two questions for each of the photos will help you practice applying your knowledge of head…

    • Quiz 11: Head feather groups and simple color patterns 

      February 22, 2012

      This quiz is about taking the feather groups you've learned in previous quizzes, and applying them to real birds, to see how color patterns follow the basic…

    • Quiz 10: Head feathers - without markings 

      February 21, 2012

      This quiz features a Dark-eyed Junco, a species with no discernible color pattern on the head. How can you distinguish groups of head feathers with no color…

    • Quiz 9: More on Head feathers 

      February 20, 2012

      Here is a close-up of the head of a Song Sparrow, showing the feather groups and feather markings really well. In the copy below, I've outlined the feather…

    • Quiz 8: Introduction to head feathers 

      February 16, 2012

      Color patterns on the heads of birds are some of the most complex, and also some of the most important for identification. Understanding those patterns is…

    • Quiz 7: more on bird weights, with a twist 

      February 15, 2012

      In this quiz your challenge is to compare the weight of the birds with common household items. There is variation in the weight of the birds, and variation in…

    • Quiz on Bird Topography: Wings 3 

      February 10, 2012

      Each label in the photo above points to a feather group associated with the wings. In the quiz below, choose the correct name for that labeled feather…

    • Quiz on Bird Topography: Wings 2 

      February 8, 2012

      Identify the two labeled feather groups in the quiz below, with a couple of bonus questions.

    • A quiz on bird wing feathers 

      February 7, 2012

      The major groups of feathers on the wing are showing well on this American Robin, and each is labeled with a letter. In the quiz below, select the letter…

  • Quiz: estimating numbers  (5)
    • Quiz 52: More numbers 

      September 11, 2012

      Here are three more "flocks" of lentils that need to be estimated. If you need an extra challenge, give yourself a time limit to come up with each number.

    • Quiz 51: Estimating Numbers 

      September 6, 2012

      Another quiz to test your skill at estimating numbers of birds in flocks.

    • Quiz 49: Estimating numbers of birds 

      August 21, 2012

      This time the answers are arranged randomly, instead of sequentially, and I think this makes it a little harder, since it's harder to use the range of possible…

    • Quiz 47 - More estimating numbers 

      August 14, 2012

    • Quiz 46 - Estimating numbers 

      August 11, 2012

      Estimating numbers in flocks of birds is a skill that birders need to practice, but we rarely get a chance to test ourselves. We see a flock, guess the total…

  • Quiz: Trees  (2)
    • Quiz 52: Trees for birders 

      September 10, 2012

      The quiz below shows four photographs of the leafy crowns of trees, as you might see them while looking for birds through binoculars or telescopes. Difference…

    • Trees in their spring colors 

      May 11, 2012

      I've been neglecting trees in my posts recently, but here in Massachusetts spring is the best time of year for tree-watching, and today the sun was out…