VCE's final summer field session on Mt. Mansfield Tuesday evening
started on a rough note, as a torrential downpour caught us off-guard
while we were out setting mist nets. However, we gradually dried out
with the steadily improving weather, and yesterday morning was
productive. Most montane forest nests have clearly hatched, if not
fledged, and vocal activity of all species was more pronounced than
during the previous 2-3 weeks. We mist-netted or observed fledglings of
Blackpoll and Yellow-rumped warbler, Dark-eyed Junco, White-throated
Sparrow, and American Robin. We were surprised to capture 4 juvenile
and apparently independent Hermit Thrushes, which do not breed on the
ridgeline. Other mist net captures included 11 Bicknell's Thrushes -- 4
unbanded males, 6 birds that we had already captured earlier in the
season, and one 6 year-old male with a solar geolocator that had managed
to elude us all summer.
In addition to free-flying juveniles, signs that the avian nesting
season is waning included several females of different species with
regressing brood/incubation patches, and a number of adult birds in the
early stages of flight feather molt. Most migrant songbirds fit their
annual molt (an energy-intensive undertaking) between the end of
breeding and departure for fall migration, so finding thrushes and
warblers with their innermost primaries missing is a sure sign of things
to come. By the end of this month, the montane forest will be a quiet
place, as vocalizing becomes scarce and adults lay low while in heavy molt.
We'll make a final foray to Mansfield in early to mid-September, when
Bicknell's Thrushes typically show a brief resurgence of activity,
including calling and singing, before they head south later in the month
or during early October.
Chris
--
Chris Rimmer
Vermont Center for Ecostudies
P.O. Box 420
Norwich, VT 05055
802-649-1431 ext. 1
http://www.vtecostudies.org
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