• This week at Powdermill, we continued to increase the number of new species banded, adding 20 to the Spring 2004 banding list, more than half of which were wood warblers.  Weather continued to impact our banding effort this week forcing mid-morning closing of the nets due to the heat on four out of our six banding days.  However, we still managed to enter the beginning of our peak spring migration period with respectable totals and with our top two spots this week being taken over by warblers: Nashville Warbler (46 banded) and Magnolia Warbler (33).

We thank Randi Gerrish, Tom Greg, Carroll Labarthe, David Liebmann, Felicity Newell, and Valeria Ojeda for their help this week with banding.

• Tuesday, May 4:We banded two new species today; Northern Parula and this pair (an adult, ASY male, and an immature, SY female) of Baltimore Orioles caught together in the same net, nicely complementing our Orchard Oriole pair (an immature, SY, male, and an adult, ASY, female) from last week.

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• Wednesday, May 5: Our most favorable day, being calm, warm (high of 68°), and overcast, inspired us for a full day of banding and 470 net hours (second highest this season).  We added five new species of birds; Barn Swallow, Tennessee Warbler, Black-throated Blue Warbler, Blackburnian Warbler, and White-crowned Sparrow.

• We also captured two more Ruby-throated Hummingbirds, bringing our season total to five.  The photo below not only exemplifies the well-known sexual plumage dimorphism in this species (male on the left with the ruby throat), but also the reversed sexual size dimorphism (females larger than males) generally characteristic of the smaller hummingbird species.

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In our recently published Relationships among body mass, fat, wing length, age, and sex for 170 species of birds banded at Powdermill Nature Reserve (Eastern Bird Banding Association Monograph No. 1), based on a sample size of 5,196 birds, an adult female with no fat weighs 3.3g, on average, while an adult male with no fat weighs 2.9g.  Our wing length summary shows that an average adult female measures 44.5 mm, while an adult male has an average wing length of 38.8 mm.  In addition, statistical analyses in which we tested for possible age and sex effects on body mass and wing length showed that there are significant effects of both age and sex on body mass, with sex explaining a far greater percentage (15%) of the variance.  We might, therefore, expect greater biological significance to sex differences in body mass in this species, which has been previously discussed by our two senior banders at Powdermill, Robert Mulvihill and Robert Leberman (1992. A Possible relationship between reversed sexual size dimorphism and reduced male survivorship in the Ruby-throated Hummingbird, Condor 94:480-489).

 

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• Friday, May 7:We banded five new species today with one in particular causing some excitement.  We have banded no more than three Orange-crowned Warblers in any spring at Powdermill, and some springs we have missed banding OCWAs altogether. Catching two in one day was a particular surprise, because that has only ever happened twice before in spring in the 43 year history of the banding program.   The bird below is an immature (SY) of uncertain sex (small amount of orange in crown and an intermediate wing length).

• The other four new species were Spotted Sandpiper, Traill's Flycatcher, Canada Warbler, and Chestnut-sided Warbler.  In the picture below, both are males with the bright yellow cap and dark face mask,  but note the difference in the extent of chestnut siding between the immature (SY) left and the adult (ASY) right.  Adults will also, on average, have a stronger connection between the chestnut siding and black malar area.

• In addition to the birds mentioned above, we netted an adult American Redstart with an interesting tail coloration.  The yellow color in the tail and the wings in redstarts is characteristically a feature of females or SY males.  This bird, however, had the typical adult male plumage everywhere else on its body except for the right side of the tail.  This bird most likely lost the feathers on the right side of his tail on his wintering grounds, following his definitive prebasic molt last fall.  At the time he was regrowing his accidentally lost rectrices, the particular carotenoid pigments needed for synthesizing the usual orange tail spot color apparently were deficient in his food supply.

• Saturday, May 8:We added Gray-cheeked Thrush and Wilson's Warbler to our list of species banded this spring.  We are posting the picture below of an adult (ASY) male Magnolia Warbler as a follow up to last weeks atypically plumaged bird of the same age and sex.  This fine example was one of 14 MAWAs banded today, making it the species of the day.

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• Sunday, May 9:With 32 species of birds banded, we tied Friday's species total, making these the most diverse banding days yet this spring.  Among these were the final four new species for the week:  Philadelphia Vireo (pictured on home page), this immature (SY) Veery of unknown sex,

• this second year male Bay-breasted Warbler,

• and, finally, the following...an adult (ASY) female with very prominent tiger-like streaking on the breast (hint!).  Can you identify this warbler? (see next photo below of an adult male of the same species for the answer!)

• The following photo of an adult male of the species pictured above was taken outside the banding office this week by our own Mike Lanzone.  It was heard singing and observed feeding in this same spruce tree for much of the afternoon.

Last Updated on 5/12/04
By Adrienne J. Leppold