This week of May typically marks the last opportunity for us to catch spring migrants in significant numbers and had us hoping for a few final chances at getting a >100 bird day before the end of the spring season.  Unfortunately, all but one day was delayed with early morning thunderstorms, and the summer like temperatures continued to force closing of nets by late morning on most days, greatly reducing our banding effort.  Nearly three inches of rain fell at Powdermill this week.  We only banded two new species for the season, Downy Woodpecker and a long overdue Yellow-bellied Flycatcher (in recent years the first of this species has been caught by May 11th).  Cedar Waxwing greatly improved the final weekly total by adding 30 to the list which placed it in our top spot this week.

Despite the limited banding effort, we had plenty of visitors and volunteers here this week willing to help where needed.  We thank Dan Hinnebusch, Mike Lohr, and Jake Mohlmann (seasonal biological technicians living at Powdermill this summer while studying grassland birds in Somerset County for Pennsylvania State University), and also Annie Lindsay, Felicity Newell, Iona Newell, and Paul Sweet (one of the hired and recently arrived point counters for the 2nd PA Breeding Bird Atlas).

• Thursday, May 20 was our most productive day this week with 57 birds banded, including the two new species for the season.  Pictured below is our first Yellow-bellied Flycatcher of the season, an immature (i.e., second year, SY) bird.  Among all the Empidoniax flycatchers, the YBFL has been dubbed the "cute one" by our senior bird banders, Bob Mulvihill and Bob Leberman, because of its disproportionately large, rounded head shape for its small bill and body size (compare to the Acadian Flycatcher pictured in the next section below).  Of course, in addition to being "cute," YBFLs also can be distinguished in hand by the the more conventional observation that they have grayish legs and a slightly emarginated primary six.  Some, like this bird, are not excessively yellowish in their underparts, although, whatever yellow there is extends up onto the chin.

• The week of Empids continued; below is a photo of an immature (SY) Acadian Flycatcher also banded this week.  Note the pale yellowish color of the mouth lining on this immature as compared to the pale pink mouth lining color of the adult Acadian banded last week.  As was also mentioned last week, we have noticed that immatures, even in the spring, tend to have a more yellowish mouth lining color, however, still pale enough to be a helpful identification characteristic for distinguishing this from other Empidonax species.  The closeup photo of the wing shows molt limits from the species' typically very restricted first prebasic (first fall), and/or first prealternate (first spring) molts.  It has molted a small clump of its innermost lesser coverts (small feathers at the top center of the photo; molted ones edged with greenish), two inner median coverts (in the first row of larger coverts below the lessers; molted ones fresher and tipped with light yellow rather than worn and tipped with white), and one inner greater covert (the row of largest coverts below the medians; the molted GC being darker and fresher than the surrounding retained juvenal greater coverts).

 

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• Banding birds, it seems, goes hand-in-hand with surprises and conundrums, in this case, a slightly confusing spring warbler!  On Saturday, May 22, we netted this immature (SY) female Bay-breasted Warbler which appeared so dull that we briefly considered the possibility of its being a Blackpoll x Bay-breasted hybrid.  In May 2001, we netted an immature female that we decided probably was a Blackpoll x Bay-breasted Hybrid (click here for pictures and discussion of this bird).  Like that hyrbid, the bird captured this spring lacked any chestnut coloring on its cap, a trait, in our limited experience with this species in spring, that usually is present to some degree in females, even SYs.  We don't net very many BBWAs in spring, so we simply do not have as much experience with the range of plumage variation shown within and across age/sex classes in this species as we do, for example, with the Magnolia Warbler, a much commoner spring migrant here at Powdermill.  Seeing a somewhat unusual example in isolation from others to which it can be compared can, at times, be perplexing--a good thing for banders and birders to always keep in the back of their minds!

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With careful consideration of the entire plumage, though, all other features confidently favored its being simply a very dull SY female BBWA.  Although faint, the bay color on the sides was fairly conspicuous (more so than in the hybrid netted in 2001).  The bird lacked any streaking on its flanks (a Blackpoll trait that the earlier hybrid exhibited), she had a duller face pattern without any distinct eyeline, and her legs were more grayish than yellow.

• Lastly, we include a couple photographs of wings from two female Indigo Buntings banded this week for our banders and readers interested in or studying molt.  The above photo is clearly of a SY bird:  very brown/worn first basic wing coverts (and even duller retained juvenal primary coverts) accompanied by a molt limit between the outermost five, darker and blacker shafted, molted first basic primaries and the rest of the browner and more worn retained juvenal primaries, as well as another molt limit (less obvious in the photo) between the retained outer five secondaries and the molted inner secondaries 6-9.  In comparison, the bottom photo shows a far less worn bird, which nonetheless showed distinct molt limits between the outer three primaries and the inner six, and between the outer six and the inner three secondaries (the tertials), making it either an SY (albeit an exceptionally unworn one) or an adult (ASY) that had included the three outer primaries in its prealternate molt (a molt pattern not known for this species), or perhaps in the second stage of an interrupted prebasic molt.   We aged it conservatively as an AHY.

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Last Updated on 5/27/04
By Adrienne J. Leppold