• Spring migration at Powdermill continued to progress very slowly, and while many species have been reported from areas near Powdermill, only 288 birds of 44 species were banded during the last two weeks in April.  With our March and April banding totals commonly reaching more than a thousand birds, our comparatively meager total of 667 individuals thus far is a little disappointing.  Furthermore, the 24 new species added to our spring total during the recent period is far fewer than what we might have expected based on species diversity for this period during the last few years.

 

 
 
 

Ruby-crowned Kinglet was first with 60; Chipping Sparrow was second with 36 banded.  Nonetheless, between a few really "good gets" and our second bander development workshop of the spring, we still found plenty enough to keep us busy and there were some highlights well worth the mentioning.

• Tail feather shape often is used by banders as a helpful tool for ageing.  Two Yellow-rumped Warblers banded on April 20th were instructive concerning the pitfalls of relying too much on tail feather shape in making age determinations.  One was an SY and the other an ASY.  Can you tell which is which?

• The following wing pictures are of the same two birds, the top wing photom goes with the above left tail photo; the bottom wing belongs to the bird with the tail pictured on the right.  Now can you tell which is the SY and which is the ASY?

If you said the tail on the right side of the photo and the lower wing photo belong to the SY Yellow-rump, you're right.  Note the molt limit between the carpal covert and alula covert (A1), the small feather just under the finger nail.  During its first prebasic molt last fall, this bird replaced all its greater coverts out to and including the much darker and nicely edged carpal covert, then stopped molting.  Additionally, Pyle 1997 writes, "there is also more overlap in rect shape by age in this species than in other Dendroica warblers," emphasizing the importance of ageing by molt limits.

However, to complicate things somewhat, many Dendroica warblers (both adults and young) undergo a prealternate molt, resulting in a second molt limit in the spring and, ultimately, three generations of feathers on an SY bird.  In the photo above, greater coverts 4-10 were molted this spring (i.e. the prealternate molt limit is between GC three and four).  Thus the three generations are: GC 4-10 = most recently molted feathers from the prealternate molt this spring; GC 1-3 and carpal covert = retained feathers from the first prebasic molt last fall; and finally, all three alula, primary coverts, and flight feathers retained juvenal.

Lastly, the adult wing in the top photo also has a prealternate molt limit between GC four and five, but note, there is no difference between the carpal covert and three alula feathers.  So, ultimately, on an adult bird in the spring there will be only two generations of feathers on the wing, as opposed to three: in this case, GC 5-10 = most recently molted feathers from prealternate molt this spring; GC 1-4, carpal covert, all three alula, primary coverts and flight feathers replaced during prebasic molt last fall.
 

• Also banded on April 20th, was the second earliest Red-eyed Vireo ever banded at Powdermill.  The earliest on April 17th in 2003 is one of only five other April banding records for this species.  And because we couldn't help but show it off, one of two White-eyed Vireos banded this period also is pictured below.

 

• On Saturday, April 23, we banded our first of two Spotted Sandpipers, and

• on Sunday, we banded our first Common Yellowthroat of the season, this second year male.

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• After adding six swallow nest boxes around our ponds, it was about time we caught one of the many Tree Swallows that had been prospecting for summer homes throughout the last few weeks.

• On Tuesday, April 26th, our bird house additions around the ponds might have also played a part in attracting the seventh ever Prothonotary Warbler (a cavity nester) to the banding area.  Woohoo!!!

• Being near the northern edge of it breeding range, PROW is a localized rarity not just in and around Powdermill, but throughout Pennsylvania.  The species prefers wooded swamps, often along riparian corridors with slow moving water.  Just an hour or so before it appeared in our mist nets, this beautiful adult (ASY) male PROW was observed (and correctly identified, aged and sexed!) by Powdermill's Director (and beginning birder), Dr. David Smith, through his ofice window, which overlooks a shrubby wooded swamp alongside Powdermill Run.

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• Unfortunately, our bander workshop participants arrived just a few hours too late to see the Prothonotary Warbler, but they were around for some of our other seasonal firsts like  Palm and Worm-eating Warbler, this adult Northern Waterthrush

• this Brown Thrasher (looking very "Ha-cha-cha-cha-cha" in the photo below)

• and one of four Northern Rough-winged Swallows (another "good get" for us, because the long term spring average at Powdermill is less than one).

• With 60 banded, not only was Ruby-crowned Kinglet the bird for the period, it was certainly the bird of the week during the workshop.  In the picture below, visiting bander, Frank Rouse, from Indianapolis (himself not diminutive!), gently holds and skillfully measures one of the many diminutive kinglets we caught during the bander workshop.

• We thank our bander workshop participants, from left to right in the photo below, Fred and Carol McCullough from Pittsburgh, Frank Rouse, Jean Bickal from Hopewell, New Jersey, Margaret Hahn (kneeling) from Kalamazoo, Michigan, from Powdermill, Adrienne Lepold and Bob Leberman (also kneeling, with Puppy Mulvihill) for their help during the workshop week and for their patience with the unexpectedly (and unusually) low volume and diversity of birds.  Notwithstanding this, we hope it was a beneficial experience for all involved.

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Late April sunrise over Crisp Pond

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Last Updated on 05/05/05
By Adrienne J. Leppold