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 and look for birds. During this trip I spotted a distant loon on the water, which struck me as being large […]
An apparent hybrid Yellow-billed x Common Loon Read More »
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 image to see the proof). I’ve been pondering this illusion and wondering how often we see similar effects in bird identification. I suspect that a lot
Optical illusions and bird identification Read More »
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 southeastern Arizona, and devoted a lot of time to studying the White-crowned Sparrows. At that date most of them were migrant Interior West birds of subspecies Z. l. oriantha. Most of
Distinguishing Interior West from Western Taiga White-crowned Sparrows Read More »
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 record and the first spring record in the east. When other birders saw the photos, some questioned why the bird was not an Orchard Oriole (common in
A “mystery” oriole and the limitations of identification by impression Read More »
The Mexican Duck was formerly considered a species (Anas diazi), and is currently lumped with Mallard (as subspecies Anas platyrhynchos diazi), but recent DNA studies suggest that Mottled Duck (not Mallard) is its closest relative (McCracken et al. 2001). Whatever its genetic background, it is clear from field observations that Mexican Ducks and Mallards interbreed
Intergradation between Mexican Duck and Mallard in Arizona Read More »
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 already well-versed in the intricacies of Brant. Over the last fifteen or so years I have seen several odd “gray-bellied” Brant along the US Atlantic coast. This spring I finally
Three interesting Brant from Massachusetts Read More »
Identifying subspecies adds richness to your birding by adding another layer of understanding. What’s more, during spring migration, behavior can offer a quick and fairly reliable clue to use when distinguishing local breeders from migrants. This is simply an extension of a bit of advice often given for identifying shorebirds: to watch for birds around
Identifying subspecies by behavior – Savannah Sparrow Read More »
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 distinctive in adult male plumage and are split into two species by many authorities. Green-winged Teal (American) – Anas crecca carolinensis Common Teal (Eurasian) – Anas crecca crecca ((Common Teal nests in
Distinguishing Green-winged and Common Teal Read More »
Summary The two subspecies of Purple Finch are fairly distinctive with well-defined ranges. They are best distinguished by overall impression of color and pattern, and more objectively by details of back and head pattern. Virtually all individuals should be safely identifiable in the field, but the frequency and extent of intergradation is unknown. Eastern Purple
Distinguishing the subspecies of Purple Finch Read More »
Not really. Only under ideal conditions and with reference to location. Mountain Chickadee is found throughout much of the montane coniferous forest of the west, and up to seven subspecies have been described and named. These were sorted by Behle (1956) into Rocky Mountain, Great Basin, and California groups which differ in a complex mosaic
Can subspecies of Mountain Chickadee be identified in the field? Read More »