Thursday, January 12, 2006

Lark Buntings

Tonight's guest speaker at the monthly Fort Collins Audubon meeting was Amy Yackel Adams who spoke about her CSU dissertation work on Lark Buntings and their population status at the Pawnee National Grasslands. It was a very nice talk in front of an attentive and good-sized crowd. Some take-away points:
  • The Pawnee Grasslands (PNG) are home to the highest breeding concentrations of Lark Buntings (LABU). She says the birds are generally very prompt in arriving on May 1 in spring migration. The males show up about 2 weeks before the females.
  • It's been estimated that LABU populations overall are declining at about 2.1%/year in recent years, which is quite high.
  • LABU juvenile survival rates are about 20-30%, which is pretty low by passerine standards.
  • These low rates are attributable in part to their being ground nesters, and are subject to significant predation, ranging from 13-Lined Ground Squirrels to weasels to raptors. Someone did ask during the Q&A whether chemical contamination may play a part, but Amy couldn't point to any studies that have been done on this. Her anecdotal evidence did suggest some possibility of that, based on failed nests with fragile eggshells, but nothing conclusive.
  • LABU practices "brood division" during the raising of the young. That is, say, in a nest with 4 fledglings, the male and female with each take two "under their wing" and sequester them separately in different locations, for feeding, etc. Apparently only a couple dozen North American species are known to do this, although this may be because other species haven't been followed and studied to the extent that LABUs were in her work.
  • Neighbor Nick asked her what she would recommend as the one single thing that could be done from a conservation standpoint in order to improve the chances of reproductive success for LABU at PNG. She suggested something along the lines of reducing habitat fragmentation, which is a very big problem at PNG. In the case of PNG, this fragmentation reduces the ability of coyotes (which get hunted off) to control their usual prey, the ground squirrels - and thus the LABU end up with more predators of their own.
Of course, there was more, but it's getting late and I want to get this off before heading to bed. Bravo FCAS for yet another great presentation!

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