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Pictorial Highlights, Early Fall 2011

August-September Warblers 2011

One group of birds that people get especially excited about during migration are the wood warblers that breed in North America.  This is a wonderfully diverse and colorful assemblage of birds, but determining the species age and sex of an individual can be challenging, even when they are in the hand.  Overall, keep in mind that the really drab birds are probably hatching year females, the ones with a lot of color are likely after-hatching-year males, and the ones with an intermediate amount of color in their plumage are either after-hatching-year females or hatching-year males (those 2 groups often have very similar plumages). 

oven Although young and adult Ovenbirds have essentially the same general plumage, there are some slight differences.  The rusty tipping on this bird's tertials identify it as a hatching-year bird (adults lack the rusty tipping).  By spring this tipping frequently is worn off, and age is best determined by using the presence or absence of a molt limit.  As in many birds, the shape of the tail also can be useful in ageing warblers. 
nowa A similar pattern can be found in Northern Waterthrush.  The tertials of HY birds (in the fall) often have white tipping, while adults lack this feature.  The white tipped tertials indicate the bird in the photo is a hatching-year.
bwwa This is an after-hatching-year, male Blue-winged Warbler, a species that is relatively uncommon at Powdermill.  The lack of a molt limit in the alula feathers (A1,A2,A3) indicates this is an adult bird.   Its closest relative, the Golden-winged Warbler, is much less common and, we have failed to capture any this fall.  The rapidly declining Golden-winged Warbler is currently being petitioned to be granted Federal protection under the Endangered Species Act. 
howa The age of a male Hooded Warbler is usually identifiable with a quick examination of the throat feathers.  If the black throat has extensive yellow tipping it is a hatching-year and if it lacks this tipping (or has very little) it is an after-hatching-year.  Therefore, the photographed bird is an AHY male. 
howa This is a good example of a hatching-year male Hooded Warbler.
cerw The next set of pictures are of warblers that can be difficult to identify during the fall.  See how you do on this quiz and look for the answers at the bottom of the page.

A side by side shot of a Bay-breasted and Blackpoll Warbler.
Hatching year Connecticut and Mourning Warbler.  Look for the complete eye ring on the Connecticut and the broken eye ring of the Mourning. 

In what was a personal record, we captured 5 Connecticut Warblers on the morning of September 24 (4 unbanded, 1 banded). 
cmwas Hatching-year female and male Cape May Warblers.  HY females can be a tricky one to identify when birding, but look for the heavily streaked breast on a drably plumaged warbler. 
mowa An after-hatching-year Mourning Warbler.
amre An adult female American Redstart with nearly white (rather than yellow) wing and tail patches.
mawa A leucistic adult Magnolia Warbler.
baww An after-hatching-year Black-and-white Warbler.  This bird can be aged an AHY by its plumage but also notice the rounded shape of the outer tail feathers.
cmwa An AHY male Cape May Warbler foraging in a spruce tree near the banding lab (thanks Fabian for this great photo!)
btbw A HY male Black-throated Blue Warbler with a white eye line and partial under-eye arc, similar to a female.
fat tewa A fat Tennessee Warbler ready to head south and continue the journey to its South American wintering grounds. 

Although this bird is primarily insectivorous on the breeding grounds, it will become omnivorous and consume nectar on the wintering areas. 
Answers to the quiz birds: Cerulean Warbler, Nashville Warbler, Prairie Warbler, Tennessee Warbler, Wilson's Warbler, Bay-breasted Warbler, Blackpoll Warbler, Cape May Warbler, Blackburnian Warbler, Magnolia Warbler, Palm Warbler.  
We thank Fabian Meijer for a number of great photos of birds in the hand and the bush.  Fabian is a Dutch "ringer" helping out at Powdermill this fall.  

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