Pictorial_Highlights_April

PICTORIAL HIGHLIGHTS, APRIL 2002

Among the three Red-winged Blackbirds banded 1-7 April, 2002 was this very unusual probable after second year (ASY) female. Although female RWBLs can have varying degrees of orange coloration among their lesser coverts (the "shoulder" of the wing), we have never seen a female with an epaulet as colorful as this one, approaching the intensity of a second-year (SY) male's. Then again, we don't band very many RWBLs. Has anyone else ever seen one this brightly colored?

As we mentioned previously this spring, there is little or no overlap in the seasonal occurrence of wintering American Tree Sparrows and breeding resident Chipping Sparrows at Powdermill. Our first CHSPs returned in early April 2002, but we have not recorded an ATSP since the end of March.

We banded ten more Red-winged Blackbirds during the week of 4/8-4/14, all of them males. Last week (see above on this page) we published the photo of an unusually bright ASY female RWBL. In the photo strip below (from left to right), the epaulet of that female is compared to a typical SY male, a brighter SY male, and an ASY male.

We banded our first Palm Warblers on 4/11 and 4/13--both were males of the more easterly "Yellow" race, which is comparatively very rare west of the main ridges of the Appalachians. Robert Leberman, Powdermill's principal bander, currently is preparing a manuscript on the occurrence of the two forms at Powdermill. Briefly, out of some 1,300 Palm Warblers banded at Powdermill since 1961, only 50 (4%) have been ascribed to the eastern race. Both forms are much more commonly and frequently captured in the fall migration, but "Yellow" Palm Warblers comprise more than 30% of all spring captures at Powdermill, compared to <2% in fall. "Yellow" Palm Wablers migrate much earlier in spring than the "Western" race--in fact, we have never banded a "Western" Palm Warbler on a date as early as the two eastern race birds were banded this week. Distinguishing features for the "Yellow" eastern race are little or no contrast between the yellow undertail coverts and the lower belly, a yellower lower eye ring, and heavier, more extensive and more richly colored streaks on the breast and sides. The bird pictured below is a second year, SY, male.

In spring, banders are faced with the challenge of trying to distinguish between second-year (SY; hatched in the previous calendar year) and after second-year (ASY; hatched at least two calendar years prior). One useful criterion is tail feather shape, the retained juvenal rectrices of many SY birds being comparatively more narrow and pointed than comparable "adult" rectrices.

A few weeks ago we showed the case of an SY Dark-eyed Junco that had adventitiously replaced several juvenal rectrices, thereby providing a side-by-side comparison between retained juvenal and adult-like replacement rectrices. Below is a photo of a Black-capped Chickadee showing similar mixed age rectrices. The eight rectrices on the left side of the photo (the bird's right rectrices 1-6, numbered from the center, and left rectrices 1 & 2) are adult-like replacement rectrices, while the four on the right (the bird's left rectrices 3-6) are retained juvenal feathers. Note the more worn and pointed appearance of the juvenal rectrices, as well as the much more extensive white edging on the adult-like replacement feathers. The very fact that tail feathers frequently are lost and replaced between normal molts is one of the reasons why tail feather shape must be used with great caution by banders, and only with other supporting characters (e.g., molt limits), when determining the ages of birds in hand.

At the end of this week we bid farewell to our faithful Research Assistant, Adrienne Leppold, a graduate in Wildlife Biology at California University of Pennsylvania. Adrienne began here as a volunteer banding intern during early spring 2001, during which time she also assisted with data entry for various research projects. She took a seasonal position as bander and nest-finder for songbird studies in southwestern Alaska during the summer and returned to Powdermill in time to help with our record fall 2001 banding season. Beginning last fall, and throughout the winter, Adrienne has assisted us part-time with a major research project--the summarization and analysis of nearly 300,000 original Powdermill banding records for a reference publication for banders and avian ecologists on body mass and wing length variation in more than 125 species of birds. This publication likely will be the most comprehensive of its kind (easily eclipsing an earlier compendium of Powdermill body mass data published in 1978 by Mary Clench and Robert Leberman (Carnegie Museum of Natural History Special Publication No. 5), and its completion in the very near future is thanks largely to Adrienne's dedicated efforts. Adrienne is heading off to Alaska again this spring and summer, this time to study populations of cliff-nesting seabirds. Many thanks, Adrienne, for all your hard work--we'll see you in October!

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