Summer Season--2nd Half
NOTES & HIGHLIGHTS
(4 July-31July)
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Banding during the second half of
the summer (18 banding days, July 4-July 31) was twice as busy as in June,
and nearly half of July's total number of birds (577) was banded over the
course of six consecutive banding days, from 15-20 July. 105 birds
of 24 species were banded on July 16 alone, which is the sixth
highest daily summer banding total in 44 years at Powdermill.
Highest species totals that day were Cedar Waxwing (13), Song Sparrow (11),
Red-eyed Vireo (10), Gray Catbird (10), and American Redstart (8).
These same five species (although not in the same order) topped the overall
summer banding totals, too. In all, we banded 865 birds of 57 species
this summer, far fewer than last summer's record setting 1,500 birds, but
above the long-term average of 725. For a complete breakdown of our
summer 2005 totals by species and by first and second halves of the season,
as well as a comparison with long-term averages, standard deviations, and
maxima for the same species, click
here.
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The second half of the summer banding
season produced more than a few unusual observations.
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First, an unusual occurrence
on July 6 was the capture together in a net of a juvenile Brown-headed
Cowbird and its presumed unwitting parent, a Red-eyed Vireo (a frequent
host for the brood parasitic BHCO). We generally band and see very
few cowbird fledglings at Powdermill, despite the fact that many frequently
parasitized species, like Red-eyed Vireo, Song Sparrow, Chipping Sparrow,
and Yellow Warbler, are very common in the banding area. In fact,
in 44 years only 43 HY BHCOs have ever been banded here in July, and most
of these were banded in the first twenty years of the program's operation,
when the banding site was more open and surrounding farms ran more livestock.
Including the one pictured below, only six young BHCOs have been banded
in July since 1990. In just three other cases was the probable adoptive
parent noted as part of our banding record: they were American Redstart,
Hooded Warbler, and Indigo Bunting.
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The wing of this second-year (SY)
female Scarlet Tanager banded on July 9 was unusual because it has two
extra feathers: ten secondaries instead of nine, and eleven greater
coverts instead of ten.
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In keeping with
our "unusual" theme, what do you think might be odd about this handsome
Hooded Warbler banded on July 12?
How about the fact that it's a female (with a brood
patch)!
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An unusual but increasingly frequent
(at Powdermill, at least) plumage variation for Scarlet Tanager probably
is the result of the same diet that produces a similar feather color shift
(from yellow to orange) in Cedar Waxwings. Tartarian and Morrow's
honeysuckle berries contain a red pigment, rhodoxanthin, which if consumed
in large quantities, can become incorporated along with normal yellow carotenoid
pigments in growing feathers--in this case, scattered body feathers replacing
the streaked gray and white juvenal plumage of this juvenile female
SCTA banded on July 16. We have even observed adult males at this
time of year replacing their scarlet alternate plumage with scattered bright
orange, rather than yellow basic feathering.
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Our list of unusual orange variant
species grew by one more on July 16, when we caught this hatching year
(HY) Yellow Warbler with orange feathering along the sides of its throat
and, lightly, down the center of its belly. When we published our
paper on the relationship between honeysuckle diet and increased frequency
of the orange tail band variation in Cedar Waxwings, we also reported on
the frequent occurrence of "orange-breasted" chats at Powdermill and one
instance of an orange variant Kentucky Warbler.
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Again, we believe that it is the
phenomenal abundance of the honeysuckle fruits in the banding area at the
time when so many yellow-plumaged species are actively molting that
accounts for these unusual orange variant plumages, even in species that
we might generally assume are strictly insectivorous (they aren't!)
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Some days it seems like every bird
we catch is a study unto itself! Another oddity on July 16 was this
molting Yellow Warbler. So, what makes a molting Yellow Warbler
in July unusual?...
...when it's an immature Yellow
Warbler!
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Yep!---confirmed by skulling--an
HY YWAR that was molting primaries 1,2,4,&5 and secondaries 1,2,7&8
on its right wing; primaries 1,2,&4 and secondaries 1,2,,5,6,7,&8
on its left wing. The near symmetry of this unusual molt argues against
its being adventitious, but we have never observed prebasic flight feather
molt in an HY YWAR. A few years ago, however, a fellow bander from
Wisconsin, Al Sherkow, captured and reported on an adult YWAR in June that
had an odd mixture of molted and unmolted primaries and secondaries.
Perhaps it was another anomalous case of unusually extensive first prebasic
molt like this Powdermill bird.
To reduce the amount
of time needed for downloading this page, Part 2 of July's notes and photo
highlights are continued on a second web page...
CLICK HERE>>>>for
part 2
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Last Updated on 08/14/05
By Robert S. Mulvihill
