Fall 2005 Pictorial Highlights for September 6-18

• A total of 1,199 birds of 60 species was banded at Powdermill over the course of the last twelve banding days, 440 of these being wood warblers of 22 species.  Our best day, by far, was Sunday, September 18, with 234 birds of 40 species, followed by September 11 (139 birds of 34 species), and September 14 (102 birds of 28 species).   Fortunately, we had plenty of good help throughout the period from volunteers and visitors like Annie Lindsay, Cokie Lindsay, Pam Ferkett, Jessica Maggio, Molly McDermott, Matt Shumar, Felicity Newell, Emma DeLeon, Deb Harding, Trish Miller, Fred and Carol McCullough, Todd Katzner, Rosemary Spreha, and Guy Ubaghs.  Last, but not least, our friend, colleague, and Powdermill Avian Research Center Research Associate from Cheshire, England, Dr. David Norman, arrived for a one month stint to help us with the banding and with some banding data analysis.

Leading our banding totals during the current period was Magnolia Warbler, with 114 banded (high daily total was 32 on September 18).  Leader during the previous three week period, Ruby-throated Hummingbird, came in second this time, with 102 banded. Other species banded in comparatively large numbers were Swainson's Thrush (95), Red-eyed Vireo (85), Gray Catbird (81), Common Yellowthroat (67), Hooded Warbler (58), and Rose-breasted Grosbeak (46).

• One of the 46 RBGRs banded certainly stood out from all the rest, being an example of a bilateral gynandromorph.  A bilateral gynandromorph, as stated in John Terres' Encyclopedia of North American Birds, is a term used for an animal in which part of the body is genetically female and part is genetically male.  This phenomenon is more well known in butterflies and once thought to not occur in higher vertebrates because of the overriding influence of sex hormones on secondary sexual characteristics, but this bird is actually the fourth example of this rare genetic anomaly observed at Powdermill.  Previous examples were a Northern Cardinal, an Evening Grosbeak, and an Eastern Towhee, the last displayed on this website as a highlight for the week of October 2, 2001.  Although this unusual RBGR would be an even more amazing sight to see in its breeding plumage next spring, we think you'll agree it was pretty amazing as is (and we promise, there's no photo trickery involved!)

• As glaringly obvious as the divided underparts of the bird were, the dorsum also showed subtle but clear signs of bilateral gynandromorphism, with the male half (the bird's right side) showing dark pink edging on the lesser wing coverts, compared to the olive edging on the left hand female side; in addition, the male side showed replacement of one juvenal tertial with a blackish first basic feather.   Lastly, the wing length on the male side was 100.5 mm, while that on the female side was just 97.5 mm, both near to our published (EBBA Monograph No. 1) averages for the respective sexes (female 99.0mm, n = 824; male 100.6 mm, n = 946).  This same bird was recaptured on Sunday, September 18, in a more advanced stage of first prebasic molt, and weighing 42.2 grams, or 1.4 g more than at its original capture.

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• We mentioned, but didn't show pictures of, the M/F RBGR on last week's update as a teaser for the upcoming posting.  Another teaser was our pop quiz of "confusing fall warblers."  If you didn't see last week's update and want to test your fall warbler I.D. skills before reading the answers at the bottom of this page, then click here first (use your back button to return).   Want to try for extra credit?  Here's another tough one!

Does this view of its undertail help?

Click here for answers to last week's quiz and this week's "extra credit"

• Confusing fall plumages aren't restricted to warblers, of course.  There are a number of other common species that seem to be here today and gone tomorrow.  This is because they are very conspicuous in their colorful alternate, or breeding, plumages throughout the spring and summer, literally disappear from view during their prebasic, or post-breeding molt, when they retire to densely vegetated habitats and become more skulking in their behavior, then reappear as birds of a different color.  Here are just a few examples (all adult males in definitive basic plumage):

• A "not so" Indigo Bunting

• A "less" Rose-breasted Grosbeak

• A "no longer" Scarlet Tanager

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• There are, of course, a number of kinds of birds that wear their "breeding" plumage, or equally distinctive parts of it,  year-round, making their field and in-hand identification not too challenging in fall.  Here are some recent examples:

Adult male Blue-winged Warblers, like this one banded on September 7,
look the same in the fall as in the spring

This adult male Black-and-white Warbler banded on September 17 was striking in its definitive basic plumage, even without the black throat patch that is part of its breeding plumage

Adult male Connecticut Warblers, like this one banded on September 16,
do not change their appearance much  from spring to fall

Neither do adult male Wilson's Warblers
(this one was one of several banded during the period)

A congener of the Connecticut, the Mourning Warbler adult male is distinctive in both spring and fall.
Like the Connecticut, its black throat patch will become more obvious in spring due to
wearing away of the light gray tips on its black throat feathers

Of all of the adult males pictured so far, the Magnolia (top photo) and Chestnut-sided (bottom photo)
warblers pictured below have "lost", comparatively, more of their breeding plumage, but they still
retain solid field marks that make their identification fairly straightforward
(not nearly so straightforward, of course, for individuals of the other age/sex classes of these species!)

• We'll end this update with pictures of several new species for Fall 2005 banded during the last two weeks:

• Answers to last week's confusing fall warbler pop quiz (photos, top to bottom):  Blackpoll (adult female), Blackburnian (immature female); Bay-breasted (imm. female), and Cape May (imm. female).

 

 

      Extra credit:  Palm Warbler (imm. female of the "Western" race).

Last Updated on 09/19/05
By Robert Mulvihill and Adrienne Leppold