VCE's final mist-netting foray to the Mansfield ridgeline on Monday
evening and Tuesday morning featured fine weather, a full moon, and
stellar avian activity. As is usual in mid-September, Bicknell's
Thrushes showed a resurgence of vocal activity. Calling was frequent,
especially at dusk and dawn, and several birds sang. Kent McFarland
even heard dusk flight songs. With only 15 nets, we ended up with an
all-time single-visit record of 20 Bicknell's Thrush captures - 13
immatures (young-of-the-year) and 7 adults (5 retraps from earlier in
the summer). Most responded strongly to playback, suggesting that all
age classes may be prospecting for turf and/or mates in anticipation of
being back on the mountain next spring. We know site fidelity of both
adult males and females is strong (60-65% from one year to the next), so
it may make sense for individuals to make their presence known just
prior to migrating south.
Other birds banded:
Swainson's Thrush 2
Hermit Thrush 1
Blackpoll Warbler 6
Yellow-rumped Warbler 10
White-throated Sparrow 2
Other birds captured but not banded:
Sharp-shinned Hawk 1 immature male
Red-eyed Vireo 2
Ruby-crowned Kinglet 2
Ovenbird 1
Black-throated Blue Warbler 6
Black-throated Green Warbler 3
Dark-eyed Junco 4
Miscellaneous sightings:
Common Raven 16 cavorting over and around the summit, the most we have
ever seen together in 20 years working on Mansfield
Cedar Waxwing 12+
Golden-crowned Kinglet 4
White-winged Crossbill 6 calling overhead
A memorable finale to our 2011 field season!
5 comments:
Why did you choose not to band the other birds?
Why didn't you band the other birds?
We decided early on to focus on just 5 common montane forest breeding species - 3 long-distance migrants (Bicknell's and Swainson's Thrush, Blackpoll Warbler) and 2 short- to medium-distance migrants (Yellow-rumped Warbler and White-throated Sparrow). That decision was in part to avoid becoming swamped by large of numbers of birds that need to be processed during a time when energetic needs are high, unattended eggs and young potentially vulnerable in the nest, and frequent weather changes that can take us by surprise. And, we're unlikely to collect enough data from other less common species to generate adequate sample sizes.
Wow, this is really cool. Were any of the adults recaps? And if so, were they still on territory? Have you had any young birds return to the area where they were originally captured?
Three of the adults were birds that we had banded in June or July, so presumably still on territory. However, males of this species don't maintain classical breeding territories, but occupy large and overlapping home ranges. Of several hundred juveniles we have banded on Mansfield and Stratton Mt (s. Vermont), about 10 have returned to their natal site in a subsequent year. This included a brother and sister banded as nestlings on Stratton who returned and set up shop side by side!
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