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Pictorial Highlights, Late Summer 2007

August 6 - September 2, 2007

PowderMill Bird Banding Sign This early part of the fall banding season netted us 790 "new" birds of 62 species, plus 210 recaptures. Total banding effort was 2,500 net hours, giving a capture rate (for "new" birds) of 32 birds/100 net-hours. Our total for the period included 252 wood warblers of 23 species and 56 Empidonax flycatchers of five species (two of these lumped together as "Traill's").

Top ten species banded during the period were Cedar waxing (99 banded), Gray Catbird (64), Ruby-throated Hummingbird (60), Red-eyed Vireo (55), Hooded Warbler (49), American Goldfinch (44), Common Yellowthroat (39), Magnolia Warbler (35), Rose-breasted Grosbeak (32), and American Redstart (25).

We thank Mary and Alex Shidel, Pam Ferkett, Lauren Schneider, Brent Worls, Emma DeLeon, Mike Allen, Mikey Lutmerding, Jo Anna Leachman, and David Holmes for their help with banding this period.
Juvenile Gray Catbird While we arbitrarily include August as part of our fall migration season, a lot of the birds caught during the month are, in fact, locally breeding adults and their young.

By this point in the breeding season, though, many of the "kids" caught and banded likely are products of a second (or third) brood or late re-nesting attempts. Here are just a few of the "local" birds that were still getting caught well into August:

The juvenile Gray Catbird pictured to your left apparently missed the lesson on preening. The persistent sheathing on its tail feathers gave them an odd, racket-shaped appearance.
Juvenile Common Yellowthroat A juvenile Common Yellowthroat
Immature House Wren and an immature House Wren, like the COYE above, still with a thick, fleshy "baby bird" gape. 
Prairie Warbler This HY male Prairie Warbler marked one of our first real migrants of the month and also was the first of its species banded for the fall. A frequent "miss" for us during the season, this was actually the first of three banded in August, already equaling our long-term average fall banding total for the species. 
Louisiana Waterthrush This HY Louisiana Waterthrush captured on 8/17 provided one of the latest "fall" dates for this species. Early to arrive in the spring and early to leave in the fall, it's not unusual for us to band our last migrant LOWA in July, before the official start of our fall banding season.

While the record late banding date for a LOWA at Powdermill is 9/9 (captured in 1978), only 20 other individuals have ever been caught later than 17 August in 46 years of fall banding here. 
Canada Warbler 

Canada Warbler
As we've mentioned time and time again on this website, particularly for sexually dimorphic species, correctly determining the sex of a bird more often than not depends on accurate ageing first. As we have shown before, Canada Warblers provide a very good example of this.

Compare the two photos to your left. Can you tell which one is the male and which one is the female? 

The general similarity in the appearance of the two birds to your left may be confusing until we remember that often times in sexually dimorphic species young males and adult females will look alike. With that said, all you need to know in order to answer the question is that the top photo is an AHY and bottom is an HY.
Fall warbler  Continuing on with the confusion theme, it's time again for all those "confusing" fall warblers that can give birders and banders alike cause to pause when making an I.D.

More often than not, the confusing individuals are HY females, like the bird pictured to the left.  
Blackburnian Warbler Young males warblers in fall, although often somewhat duller than adult males of the same species, usually show distinctive field enough marks and plumage patterns so that they can be readily identified.

The bird pictured to the left is an HY male Blackburnian Warbler; the one above is an HY female of the species. 
Female Hooded Warbler  On 8/15 we banded an HY female Hooded Warbler with an unusually extensive black hood. We are confident that the bird was a female because of its short wing length, 61.5 mm, and the fact that an HY male would have a much more complete black hood.

The wing length was compared to an analysis of over 2500 HOWA's as part of a study summarizing body mass and wing length statistics of birds banded at Powdermill. It is near the minimum wing length recorded for females and more than 2mm smaller than the minimum wing length ever recorded for a male. We have posted notes about similar looking birds in the summer of 2005 and fall 2004
Yellow-bellied Flycatcher  8/15 also brought us our first Yellow-bellied Flycatcher for the season. The "very cute" appearance of this Empidonax flycatcher makes this I.D. less confusing. 
Traill's Flycatcher Furthermore, there should be no confusion about the age of this Traill's Flycatcher. All molts for this species (i.e., these species, Alder and Willow) occur on the wintering grounds. So, we would expect a HY bird's wing feathers to be rather fresh looking, having just grown in this summer, in comparison to an adult bird that is now carrying 6-8 month old feathers that have been used for one long-distance migration, and which have been worn for an entire breeding season.

In addition, the freshly molted wing bars of HY Empidonax flycatchers are buffy/yellow in appearance, not whitish. So, the bird in the photo to the left is an AHY (adult). 
Nashville Warbler 8/15 continued to be a great day for firsts with this Nashville Warbler, an adult male undergoing heavy wing molt. 
Black-billed Cuckoo

Black-billed Cuckoo
This Black-billed Cuckoo, banded on 8/15, had remnants of a recent caterpillar meal on its bill - notice the green "guts" and urticating "hairs" (photo to the left).

The mess results from the cuckoo literally thrashing its prey against a branch to kill it and break off as many of the caterpillar's irritating "hairs" as possible before eating it. This cuckoo simply hadn't had time to "wipe its mouth" before it was caught in one of our nets!

David Holmes

David Holmes
Finally, that same day, we enjoyed a visit from our long-time friend and fellow bander, David Holmes, from the Appledore Island migration banding station. We made him pose for a picture because we really liked the back of his t-shirt! 

The Birds in the Band, what else?!

The design is even more clever given that David is a piano instructor (so, where's the keyboard playing warbler, David?)

Rose-breasted Grosbeak Of the 30+ Rose-breasted Grosbeaks banded in August, this was one of the few adults (an SY female). This indivual typifies the worn feathers frequently seen on birds this time of year and associated with breeding and post-breeding adults.

In this case the worn plumage is that much more dramatic because it was a SY bird still with juvenal feathers. Note the particularly obvious contrast between the retained juvenal alula and secondaries 3-6 and the freshly molted primaries, primary coverts, tertials and greater coverts. 
Emmanuel Senkoro with Hummingbird  On 8/28 we enjoyed a visit from the former director of the Western Pennsylvania Conservancy, John Oliver, and a guest of his, Emmanuel Senkoro, from Tanzania. Emmanuel is a safari/birding guide in Africa, where he met John. He was invited to the United States as an intern this fall with the Silver Lakes Nature Center in southeastern PA. While there he will be teaching visiting students about Tanzanian birds, wildlife, and culture.

This was Emmanuel's first time in the Western Hemisphere and, thus, it was his first time ever seeing a hummingbird. We were thrilled to share this special moment with him as he posed for a picture with an HY female Ruby-throat in the photo to your left. 
Wilson's Warblers On 8/28 we also caught the first Wilson's Warblers for the fall - this AHY and HY male held together in hand in the photo to the left.

Notice the much less extensive black crown of the HY on the right and the green veiling on the tips of each crown feather. 
Adult Warbler Wing

Wing Picture
While the extent of crown in the birds in the above photo is rather definitive, we always confirm the age of birds by examining the wing for presence (HY) or absence (AHY) of a molt limit.

Remember, adult females and immature males of many warbler species look alike! The top wing photo to the left is of the AHY (adult). Note the uniform sheen and appearance of the three alula feathers. The bottom photo to your left shows the very subtle A1 molt limit on the HY bird. A2 and A3 (the two larger alula feathers) in the bottom photo are just slightly browner and more dull compared to A1.

Note also that there is little or no difference in the shape of the primary coverts between the two different aged birds, even though this is given in some literature as useful character for making age determinations. There is, however, a notable difference in the shape of the flight feathers between the two birds, the HY bird in the bottom photo having much more pointed primaries and secondaries than the AHY in the top photo. The tips of the primaries and secondaries on the AHY are very round and truncate. 

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