They diverged from the two northern populations during the Pleistocene, and so they probably are true species. However, the other two subspecies, goldmani and nigrifrons, are not migratory and their populations are separate from each other. (But most birders make note of the two subspecies when they see them, anyway) As a result, these two forms are not considered to be separate species. But being migratory, they can and do hybridise where their breeding ranges overlap, giving rise to a number of interesting intergrades that can be challenging to identify in the field. The Myrtle and Audubon's forms arose after being separated by glaciers during the last ice age, and developed distinguishing physical characteristics. The American Ornithological Union (AOU) has lumped all of these birds into one species since 1973, a decision they will likely revisit, if for no other reason than to give bird watchers something to do with their life lists. nigrifrons) which occurs in northwestern Mexico, and the Guatemalan Goldman's warbler ( D. auduboni), the black-fronted warbler ( D.

coronata), the western 'Audubon's' warbler ( D. The yellow-rumped warbler has four 'forms' or subspecies: the eastern 'Myrtle' Warbler ( D. The Myrtle warbler is sometimes known as the eastern form of the yellow-rumped warbler, but I've seen this form fairly often in the Seattle area (especially in the winter), which is quite far north and west for a supposedly 'eastern' bird! My favorite nickname for the yellow-rumped warblers is 'butterbutt', in honor of their bright yellow rump when in breeding plumage. Response: This is an adult yellow-rumped 'Myrtle' warbler, Dendroica c. Can you identify this species and tell me which of the four forms it is? Question: This lovely neotropical mystery bird comes in four forms.

Yellow rumped warbler bird