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We;re so lucky to have these glimpses into critical work, at a critical time for species, so thank you Chris, & VCE!Veer Frost, Passumpsic

---- On Thu, 17 Sep 2015 21:12:30 -0400 Chris Rimmer <[log in to unmask]> wrote ---- 

The VCE crew made its final 2015 foray to Mansfield's ridgeline on 
Tuesday evening, hoping to intercept some passage migrants and hear the 
Bicknell's Thrush (BITH) parting chorus. The trip was a success on both 
counts. We left the valley's stifling heat and arrived at our study site 
- the toll road uppermost parking lot - at ~5 pm, with cooler 
temperatures and a surprisingly brisk west wind. We scurried about 
setting mist nets and had 23 open by 6:30 pm. In typical mid-September 
fashion, BITH put on a solid show at dusk, as 18-20 birds vocalized with 
vigor over ~15-20 minutes. We even heard a brief snatch of song from one 
individual. Among the 10 birds we captured before closing nets as 
darkness fell, the most surprising by far was a male Wilson's Warbler, 
the first we have ever encountered on Mansfield, even during the three 
autumns we banded on the ridgeline from 1995-97. We also captured 3 
BITH, one an adult male we had banded in mid-July, and two 
young-of-the-year. 
 
The season's reduced daylength afforded us an opportunity to sleep in, 
and we reopened our nets at the leisurely hour of 5:30 am. Again, BITH 
vocalized as they did back in July, though only calls were heard, from 
the same (presumably) 18-20 birds. Why BITH undergo this annual 
resurgence of calling just prior to their southward departure (most will 
be gone by October 1) is anyone's guess. For a species that doesn't hold 
true breeding territories, there would seem to be little imperative to 
restake claim to any turf, in hopes of reoccupying it next spring. Both 
male and female adult BITH return to Mansfield at relatively high rates, 
so perhaps there is some social context/message we humans can't 
decipher. Other songbirds are known to resume limited vocalizing 
(usually song) in fall, but I'm not aware of any that do so to the same 
extent as BITH. Hormones are likely involved, perhaps triggered by 
daylength(?). Whatever the cause/reason, it's a delight to hear, when 
all other species are virtually silent! Birds continued to call 
sporadically throughout the morning, some of them quite insistently.