This week's VCE session on Mt. Mansfield featured the first
appearance of juveniles of regularly-breeding species, as well as
several adults in very early stages of flight feather molt. Weather was
ideal for netting, with light winds and comfortable temperatures.
Thunderstorms rolled in on Tuesday night soon after we had closed our
nets and cleared the skies well before dawn, giving us a perfect day on
Wednesday. We had many visitors of all ages and geographies (MD and MA,
as well as VT), with 19 people in on the action at one point. The birds
didn't disappoint, with 2 male Black-throated Blues being the
show-stopper.
Bicknell's Thrush (BITH) again
easily outnumbered all other species, a reflection, I believe, not of
their greater abundance but of their unique spacing system, in which
males occupy large and overlapping home ranges, rather than
traditionally defended territories. With such extensive movements, it
seems likely that we capture a higher percentage of the individual BITH
on and around our study area than of species like Blackpoll Warbler and
White-throated Sparrow, which occupy much smaller, discrete territories
and have more confined movements. Most newly-banded individuals of BITH
and other species were yearlings (SYs), likely reflecting the fact that
2017 was yet another summer with low squirrel populations and solid
avian productivity. It is always surprising to capture previously banded
BITH for the first time so late in the season (we had 4), but these may
be birds whose home ranges only marginally overlap our netting area
(vs. male #2341-24303, a 2015-banded bird whom we have caught at least 6
times so far this season).
Our 53 mist net captures included:
Red-breasted Nuthatch 2 free-flying juveniles
Bicknell's Thrush 15 6 new (3 males, 3 females), 4 returns from
previous years (male and female from 2013, female from 2017, male banded as
hatching-year in Sept. 2017), 5 within-season retraps
Swainson's Thrush 1 new SY male
American Robin 3 new adult males
Blackpoll Warbler 11 9 new (5 males, 4 females), 2 within-season retraps
Black-throated Blue Warbler 2 new SY males
Yellow-rumped Warbler (Myrtle) 7 1 free-flying juvenile, 4 new males, 2 within-season retrap males
Dark-eyed Junco (Slate-colored) 8 5 free-flying juveniles, 1 new female, 2 within-season retraps
White-throated Sparrow 4 1 free-flying juvenile, 1 new male, 2 within-season retrap males
Purple Finch 1 within-season adult male retrtap
Pine Siskin 1 free-flying juvenile
Finches,
including Purples, siskins and crossbills were much less in evidence
this week than earlier in the season. There are very few cones from last
summer's crop left on the firs and spruces, and I have yet to see a
single new cone developing this year. We flushed a N. Saw-whet Owl
during our net closing on Tuesday, and we'll hope to capture one during
our final three weekly sessions this month.
________________________
Chris Rimmer
Vermont Center for Ecostudies
PO Box 420 | Norwich, Vermont 05055
802.649.1431 x202
http://vtecostudies.org/