 Extent of sea ice at the annual minimum in September 1988 (left) and September 2008 (right). From the National Snow and Ice Data Center. 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, inhibiting passage east or west along the northern shores of North America and Siberia. As can be seen in the two images above, however, those barriers have almost entirely disappeared in recent years.
In the late summer seabirds can now range much farther into the Arctic Ocean north of Alaska and Siberia than was possible in the past. In fact by September 2008 there was an ice-free passage along the entire northern coast of Russia and nearly all of Arctic Canada. This must make it easier for birds to travel between the North Pacific and North Atlantic, and may lead to some changes in bird distribution.
So far I can’t point to any pattern of records that are clearly related to the melting of the sea ice, but at least some of the recent increase of species like Slaty-backed and Glaucous-winged Gulls in Europe and eastern North America might involve birds that traveled around the margins of the late summer ice either east or west and then found themselves in the Atlantic. The recent Tufted Puffin in Britain might have been a harbinger of this.
Short-tailed Shearwater also seems like a good candidate to wander widely in the newly-open Arctic Ocean, then head south into the Atlantic. Other birds to watch for include Pacific and Atlantic Northern Fulmar in the wrong ocean. Pacific and Atlantic Common Eiders could also switch oceans, although they have probably found more or less free movement along shore leads for centuries. Only time will tell, but birders in both oceans should be alert for these potential changes.
National Snow and Ice Data Center website
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 technology to prevent bird collisions, which is very encouraging because it demonstrates a recognition of the issue by the major news media and by industry. Thanks to the work being done by Daniel Klem, New York City Audubon, FLAP, American Bird Conservancy, and many others to bring this to the forefront.
The article mentions a new UV-patterned glass manufactured in Germany and available in the US through Roeder Windows and Doors.
The article also mentions a UV-patterned window film that I wrote about previously, and says it is available from Solutia, but that website makes no mention of it.
While we wait for these products to become more widespread and less expensive, there are a lot of quick and easy ways to cut down on bird strikes. I still hear from people who have success with the highlighter method I wrote about here. Many other solutions are mentioned in my posts, in the comments, and on other websites. If you have windows, you should try one or more of these solutions.
These two species (recently split) are extremely similar in appearance. No significant differences exist in size or shape, and plumage differences are subtle and mostly overlapping. Songs differ slightly but consistently, and call notes (year round) are the most different. Voice, especially call, will be the best way to distinguish them, and identifying individual birds from photographs may be impossible in some cases.
Voice:
Differences in voice are described in the Sibley Guide, and for more detail and audio I recommend several posts by Nathan Pieplow. One cautionary point is that the difference in pitch alone is not sufficient to distinguish call notes. Both species give an “alarm chatter” that is higher and sharper than their normal call notes, so the key to accurate identification of call notes is ascertaining that you are listening to the normal one- or two-syllabled contact notes, and then comparing the pitch and quality of those. Plumage:
Arranged generally with more useful features at the top, less useful or unconfirmed at the bottom.
- Overall – Pacific darker, more rufous, and less patterned; vs. Winter Wren paler, grayer, and more patterned. The combination of reddish-brown eyebrow, cheeks, and throat, with smooth unmarked breast and neck-sides may give Pacific a distinctive overall appearance, even though no single feature is reliable.
- Neck sides – Pacific tends to have the pale sides of the neck more reddish and much less patterned than on Winter.
- Throat color – Pacific usually has throat almost as dark and richly-colored as breast; vs. pale throat contrasting with brighter breastband. Note that some Winter Wrens can have smudges of pale buff/orange on throat, and all Westerns have the throat paler than the breast (just not as pale as Winter).
- Pattern on underside – Pacific usually has breast unmarked or with a few faint bars; vs. speckled with faint, short dark and light bars.
- Eyebrow – Pacific tends to have the pale eyebrow stripe tinged rust/orange; vs. slightly paler and more clay-colored on Winter.
- Sides of breast – Pacific may have the darker and more reddish back color spreading down onto the sides of the breast; vs. sides of breast paler than the back on Winter (matching center of breast rather than back)
- Color of upperside – Pacific is dark, deep, chestnut-rufous; vs. paler, grayer brown on Winter. A subjective and subtle distinction that can be quite difficult in the usually brief and shaded glimpses these species afford. The difference might be most pronounced on the crown.
- Color of underside – Pacific darker rufous-brown; vs. paler gray-brown. Some near overlap in color makes this subjective.
- Pale spots on primaries (forming bars on the folded wing) – Pacific Wren has the pale spots on the primaries darker and more brownish on average; vs. Winter Wren with paler off-white to clay-colored spots. Note that even on Pacific these spots are paler than the back, and there is some overlap in color between the two species, so this is a fairly subjective feature and difficult to judge.
- Pattern on upperside – Pacific tends to have upperside smooth rufous-brown with faint dark bars or none; vs. upperside mottled and barred with dark and white. This helps accentuate the darker upperside of Pacific.
- White tips on greater coverts – Both species may or may not have tiny white spots at the tips of the greater coverts. On Pacific these tend to be smaller, but at the same time more conspicuous because they are surrounded by uniform dark brown; vs. Winter tends to have larger white dots, but these are less conspicuous alongside the whitish mottling of back and breast-sides.
All of this requires field testing, and now that birders have a new species to look for there will surely be a lot of new discoveries and refinements over the next few years.
- 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 Mexican species. Basic identification of these two species is already covered in the Sibley Guide to Birds, but range maps need to be updated. Below are maps showing the range of each species. These are drafts. Please comment here or contact me directly if you have definite information to add to the maps. ….Continue reading New draft range maps for Whip-poor-will →
- 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 Western species. Basic identification of these two species is already covered in the Sibley Guide to Birds, but range maps need to be updated. Below are maps showing the range of each species. These are rough drafts. Please comment here or contact me directly if you have definite information to add to the maps.
….Continue reading New draft range maps for Winter Wren →
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 splits, some name changes (mostly from the creation of new genera), and some big changes in higher-level taxonomy. Below is a summary of the changes to English and Scientific names of species in the Sibley Guide. Major changes were also made to the sequence of species, with a few new families and orders being created and moved around in the list. While these changes and the studies behind them are always enlightening, this post is confined to species-level changes of names and taxonomic status. When combined with a previous post about name changes since 2000, this updates all species and names in the Sibley Guide.
Splits (no lumps) affecting species counts:
- Eastern Whip-poor-will Caprimulgus vociferus
- Mexican Whip-poor-will Caprimulgus arizonae
Formerly considered a single species – Whip-poor-will C. vociferus – these are now split based on differences in vocalizations, DNA, etc. Identification is fully covered in the Sibley Guide.
- Winter Wren Troglodytes hiemalis
- Pacific Wren Troglodytes pacificus
Formerly considered a single species – Winter Wren T. hiemalis – and now two species based on differences in songs and calls, plumage, and lack of hybridization. Identification is covered in the Sibley Guide. I think continuing to use the name “Winter Wren” with a new meaning will lead to confusion, and would encourage birders to use “Eastern Winter Wren” and “Pacific/Western Winter Wren” for clarity. ….Continue reading New bird names in the 51st AOU Checklist supplement →
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).
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 interface, and dozens of additional sounds. More details are here.
Several users have reported issues with some of the new sounds added in this update. Uninstalling and reinstalling the program seems to resolve this, and it will be corrected in the update in a few days.
The images of Baltimore and Bullock’s Orioles were inadvertently switched in this version, and will be corrected in the update.
We’re planning to finish an emergency update by June 16th. Please contact me or add a comment here with any errors you find.
Thanks!
Updated 19 May 2010 to add McLaughlin reference
Previously I wrote about the variation in immature Ring-billed Gulls in October, using a series of photos from Cape Cod. On 18 April 2010 I devoted a little time (and a granola bar) to watching and photographing immature Ring-billed Gulls in a parking lot in Boston, MA. As always, looking closely at a common bird brings up all kinds of questions. Here is the survey of plumage variation, and I’ll follow-up with some of the questions.
 1. Two Ring-billed Gulls the same age at about the same stage of molt. The variation in these two birds arises mainly from the extent of dark markings on the newly molted head and breast feathers and the degree of wear and fading on the old retained juvenal wing coverts and tertials. Boston, MA, 18 Apr 2010. Photo copyright David Sibley. ….Continue reading Variation in immature Ring-billed Gulls – April →
 Mexican Cliff Swallow - Petrochelidon pyrrhonota swainsoni 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 of questions).
- Click to see a Google map showing the distribution of dark-fronted Cliff Swallows. Please leave a comment or contact me with any further info.
Variation in Cliff Swallow has been extensively studied in the north, but most studies have emphasized minor variations across the northern parts of the continent, and this seems to have obscured a truly distinctive subspecies in the southwest. There is only slight clinal variation across most of the continent; e.g. Browning (1992) recognizes only a single subspecies across northern and central North America. There is a cline from larger birds with whiter foreheads in the north to smaller with slightly darker foreheads to the southwest. Browning’s study did not include the southern edge of North America, where a strikingly different subspecies P. p. swainsoni (=melanogaster) just barely enters the US in southeastern Arizona.
….Continue reading Mexican Cliff Swallows →
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Birding Basics for Kindle Sibley's Birding Basics is now available as an eBook for Kindle
With free Kindle software the book can be read on PC, Mac, iPad, or iPhone, with images in color. Painting won (funds raised)
New Book Bright Wings - a new anthology of bird poetry with illustrations by David Sibley
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