Meeting Abstract

P3-143   -   Thermal acclimation in a non-migratory songbird Romero, A*; Schweizer, RM; Tobalske, BW; Semenov, G; Taylor, S; Cheviron, Z; University of Montana; University of Montana; University of Montana; University of Colorado, Boulder; University of Colorado, Boulder; University of Montana abiromero8@gmail.com

The ability to thermoregulate gives animals the flexibility to adjust to seasonal changes in temperature. Thermoregulatory ability can be modified through changes in various subordinate traits, including thermal conductance, basal and summit metabolic rates, and body condition. To improve understanding of phenotypic plasticity that facilitates cold acclimation, we investigate physiological differences between non-migratory black-capped chickadees (Poecile atricapillus, n = 7 per treatment) acclimated to cold (5˚C) or control (25˚C) environments by measuring traits that affect thermal balance. At the beginning, midpoint, and end of a 6-week experimental acclimation of chickadees we measured resting and summit metabolic rates via flow-through respirometry and body composition using quantitative magnetic resonance of live birds. After euthanasia, we measured the thermal conductance of the skin and plumage. To do so, we built an epoxy model that was placed and sutured in the skins to simulate the trunk musculature and internal organs. We heated the mold inside the skin and feathers to an internal temperature of 39˚C, and then measured the amount of power input required to maintain that internal temperature and avoid heat loss to the ambient environment (23˚C) . The power required to maintain a constant temperature is inversely proportional to the thermal conductance of the skin and feathers. We then used statistical analyses to test for a significant effect of cold acclimation on thermal conductance, maximum metabolic rate, and percent body fat. We expect that chickadees alter their thermal conductance to maintain thermal balance as a result of cold acclimation, and that cold-acclimated birds have a higher summit metabolic rate for increased heat generation. These results add to a growing body of evidence suggesting that birds use multiple mechanisms to adjust to their thermal environment.