Signs of seasonal change were evident on the Mt. Mansfield ridgeline
Wednesday night and yesterday morning. Vocalizing has diminished, the first
dependent fledglings are begging, free-flying juveniles from lower
elevations have appeared, and early failed breeders (or non-breeders) are
dispersing.

Brendan Collins and I arrived on the ridgeline at 5:30 pm, wondering if
we'd escape several bad-weather cells moving from the west. We had already
pushed our schedule back a day because of severe storms (wind, rain, hail)
that raked the mountain (and much of north-central VT) on Tuesday evening.
Heavy rains had also fallen at midday on Wed., and scattered thunderstorms
were in the forecast through at least dusk. We decided to open nets, and
good fortune prevailed, as the cells passed to our north. The dusk chorus
was as quiet as it ever gets in June, other than White-throated Sparrows,
which were in strong voice. We heard only half a dozen Bicknell's Thrushes,
with very few songs.

As predicted, yesterday's weather was much improved, and netting conditions
were excellent. Clouds still lingered on the ridgeline at dawn and the
early chorus was weak, but activity picked up as the rising sun brought
warmth and brightening. White-throats continued to dominate the vocal
airwaves, but Bicknell's and Swainson's thrushes called and sang through
the morning. We ended up capturing 62 birds, including free-flying juvenile
Red-breasted (4) and White-breasted Nuthatches (1), and a yearling
Black-throated Blue Warbler. The most surprising catch of the morning may
have been an adult female American Robin, who showed no evidence of
breeding (i.e., no incubation/brood patch) and was well into primary molt,
a good month or more ahead of schedule.

Several fledgling robins were heard or seen, and at least one pair of
Yellow-rumped Warblers was feeding fledglings.

Tuesday's violent storms may have taken a toll on some ridgeline nests.
Most evidence was indirect - we caught a surprising number of previously
unbanded adults for such a late date in the season: 8 Blackpoll Warblers (6
males, 2 females), 9 Yellow-rumped Warblers (8 males, 1 female), and 7
White-throated Sparrows (5 males, 2 females). The one active Blackpoll
Warbler nest we were following had failed - its 4 eggs had hatched, but one
chick of 4-5 days age was found dead just outside the intact nest, clearly
from exposure. The female was nowhere to be seen.

Mansfield's exposed, high-elevation ridgeline is a harsh place to live, and
extreme weather events like Tuesday's probably cause higher mortality -
especially of nests and young birds - than in nearby low elevations. If the
failed Blackpoll nest was indicative of others, the storm's effects could
explain the appearance of so many unbanded adults in our nets, as mate
bonds and territory fidelity broke down following nest losses. Few of these
migrants will be able to summon the energy to attempt a second nest at such
a late date. It will be interesting to document adult and juvenile captures
over our final 4 weekly netting sessions.

Banding totals:
Yellow-bellied Flycatcher  1
Red-breasted Nuthatch  4 free-flying juveniles
White-breasted Nuthatch  1 free-flying juvenile
Bicknell's Thrush  11 (8 males, 3 females)
Swainson's Thrush  4 (3 males, 1 female)
American Robin  2 (1 male, 1 female)
Blackpoll Warbler  13 (9 males, 4 females)
Black-throated Blue Warbler  1 yearling male
Yellow-rumped Warbler (Myrtle)  14 (11 males [9 new], 3 females)
White-throated Sparrow  11 (7 males, 4 females)

View this checklist online at
http://ebird.org/ebird/view/checklist/S30487886

________________________

Chris Rimmer
Vermont Center for Ecostudies
PO Box 420 | Norwich, Vermont 05055
802.649.1431 x1
http://vtecostudies.org/

<http://vtecostudies.org/>


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