VCE reached the halfway mark of our 2018 field season on Mt. Mansfield this week, completing our fifth banding session on Tuesday evening and Wednesday morning. We ran 25 nets under favorable conditions -- mostly calm, cool temperatures, filtered sun. Both sunset and sunrise were spectacular. Overall, singing was reduced from earlier in the month, though Am. Robins, White-throated Sparrows and Purple Finches were in full voice. I'm quite certain we've never encountered as many robins and finches up there as we have so far this year, with 10 and 11 adults banded, respectively. Pine Siskins are still present in good numbers, with a flock of 30 birds roaming around the uppermost parking lot on Wed. morning. We finally captured 2 Magnolia Warblers, our first of the season, and we netted our (more or less) annual Sharp-shinned Hawk. No real surprises this week. Still no Winter Wrens, and numbers of both Swainson's Thrush and Yellow-rumped Warbler seem relatively low.
We're on course for a "typical" or above-average Bicknell's Thrush (BITH) year, with 40 captures so far, of which 21 are new bandings and 19 birds banded in previous years. Reflecting, at least in part, last summer's absence of red squirrels (major nest predators that follow cone crop cycles) on the ridgeline, and presumed solid 2017 nesting success by BITH and other open-cup nesting species, our captures of new birds are dominated by yearlings (second-year, or SYs), which accounted for 19 of our 21 new bandings. As always, the sex ratio is skewed towards males (22 vs. 12 females among birds of known sex), reflecting the chronic imbalance that occurs in this species, with its strange polygynandrous mating system <https://en.wikipedia.org/wiki/Polygynandry>.
Our next visit will be on July 10-11, at which point I expect we'll see and capture juveniles of early-breeding species like robins, juncos, white-throats, and PUFIs. We'll also likely capture more dispersing failed and non-breeders from lower elevations, and some early-molting adults. It's hard to believe our field season is halfway to completion!
Among the 62 birds we captured over both days:
Sharp-shinned Hawk 1 new adult male Yellow-bellied Flycatcher 1 new adult of unknown sex Red-breasted Nuthatch 1 free-flying juvenile, flight feathers completely grown Ruby-crowned Kinglet 1 within-season retrap male Bicknell's Thrush 15 3 new SY males, 1 new SY female, 3 returns (1 from 2014, 2 from 2016), 8 within-season retraps Swainson's Thrush 2 1 new SY male, 1 within-season retrap female American Robin 2 new male and female Magnolia Warbler 2 new males Blackpoll Warbler 10 5 new, 1 return from 2017, 4 within-season retraps Black-throated Blue Warbler 1 new bird Yellow-rumped Warbler (Myrtle) 2 new yearling females Dark-eyed Junco (Slate-colored) 5 4 new birds, 1 within-season retrap White-throated Sparrow 7 1 new, 6 within-season retraps Purple Finch 5 1 new female 1 new SY male, 2 new and 1 retrap ASY males Pine Siskin 7 new; 1 adult female, 6 free-flying juveniles
Chris Rimmer Vermont Center for Ecostudies PO Box 420 | Norwich, Vermont 05055 802.649.1431 x202 http://vtecostudies.org/