Bird subspecies

The Newfoundland Moorhen was an American based on back color

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 origin of the Newfoundland bird. That study of photos turned up a few small differences in bill color and shape, but nothing fully reliable. Now I have finally […]

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Distinguishing Interior West from Western Taiga White-crowned Sparrows

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

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Intergradation between Mexican Duck and Mallard in Arizona

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

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Identifying subspecies by behavior – Savannah Sparrow

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

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Distinguishing Green-winged and Common Teal

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

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Distribution of Greater White-fronted Goose subspecies

The Greater White-fronted Goose (Anser albifrons) occurs throughout much of North America, but is found in largely disjunct populations. Only two North American subspecies are listed by Ely and Dzubin (1994), four by Pyle (2008), but five well-defined “population units” have occurred in North America, and there may be more. Banks (2011) recognizes four of

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Distinguishing the subspecies of Purple Finch

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

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