Date: 8/4/17 10:46 am From: Chris Rimmer <crimmer...> Subject: [VTBIRD] Mansfield revisted
Having claimed that last week's field visit to Mansfield would be VCE's last until a mid-September wrap-up trip, the lure of one more outing (and great weather) proved irresistible. A small contingent arrived on the ridgeline Tuesday evening and quickly set 23 mist nets under ideal conditions of light winds, unusually warm temperatures (~70F) and cloudless skies. Although there was virtually no dusk chorus to be heard (1 or 2 Bicknell's Thrushes and White-throated Sparrows sounded off briefly), it was a fine evening. We closed nets at dusk with 11 captures of the usual suspects.
We all slept outside on decks of the Octagon or ski patrol hut and were back on the ridgeline by 4:15 to open nets, forgetting how much shorter the days are now (we could have slept in another 10-15 mins!). All nets were open well before first light, but a hoped-for N. Saw-whet Owl failed to appear. The next 6 hours were steady, though never truly busy. We ended up with a total of 48 captures. The most noteworthy change was the absence of adults in our sample - only 1 Bicknell's Thrush, no Blackpoll Warblers, only 1 Yellow-rumped Warbler and White-throated Sparrow. Juveniles again dominated. Those adults we did capture were generally in early or mid-stages of flight feather molt, which reduces their inclination to fly. Most are also likely no longer feeding kids and so moving about less on our study site.
Our most surprising bird by far was an adult female Bay-breasted Warbler with a regressing brood patch, indicating that she had nested earlier in the season. She was almost certainly far from her breeding site, as the species is not currently known (based in large part on the second VT Breeding Bird Atlas) to nest anywhere within Vermont. She was molting her innermost 2 primaries on each wing, and her appearance could indicate a true "molt migration", but is more likely an extended post-breeding dispersal. Regardless, it was an unexpected and rewarding encounter for us.
Our banding totals:
Golden-crowned Kinglet 3 2 in full juvenal plumage; one beginning molt into first basic Bicknell's Thrush 6 1 recaptured adult male, 5 free-flying juveniles Swainson's Thrush 5 2 new males, i recaptured female, 2 juveniles (1 a recapture) Hermit Thrush 2 free-flying juvenlles American Robin 3 1 new adult female, 2 recaptured adult males Cedar Waxwing 1 adult female Black-and-white Warbler 1 immature female in first basic plumage Bay-breasted Warbler 1 adult female with regressing brood patch in early primary molt (photographed) Blackpoll Warbler 9 all free-flying juveniles in various stages of first prebasic molt Black-throated Blue Warbler 4 immatures: 2 males, 2 females in full first basic plumage Yellow-rumped Warbler (Myrtle) 2 1 new adult male in primary molt, 1 new free-flying juvenile Canada Warbler 1 immature, probable female Dark-eyed Junco (Slate-colored) 8 3 new adult females, 1 recaptured adult male, 5 juveniles including one bob-tailed bird only a day or two out of nest White-throated Sparrow 1 new adult female