Meeting Abstract

P1.101  Friday, Jan. 4  Do small wintering birds adjust their metabolic performance in response to perceived level of cold? MILBERGUE, M.*; BLIER, P.; VEZINA, F.; Univ. of Quebec in Rimouski; Univ. of Quebec in Rimouski; Univ. of Quebec in Rimouski myriam.milbergue@live.fr

Small resident bird species wintering at northern latitudes must cope with high daily energy demands, resulting mainly from thermoregulation costs. Birds respond to these conditions by physiological acclimatization where two components of metabolic performance, basal metabolic rate (BMR; maintenance energy costs) and summit metabolic rate (Msum, maximal thermogenic capacity to cold) are typically elevated. However, in most cases, parameters of metabolic performance show high variability between individuals. Although seasonal changes in BMR and Msum have been thoroughly studied for decades, we still know very little of the underlying causes for individual variation in winter metabolic performance. In this study, we investigated whether plumage insulation (measured via thermal conductance), and thus the perception of cold by individuals, was related to metabolic performance in black-capped chickadees (Poecile atricapillus) wintering in Quebec, Canada. We predicted that individuals expressing higher body conductance would also show higher levels of BMR and Msum as they would adjust their metabolic machinery to the perceived level of cold. More than 140 measurements were performed on fleshly captured individuals between November 2011 and April 2012. Conductance, BMR and Msum were measured by respirometry on all birds within 24h. Preliminary analyses suggest that individual variation in BMR and Msum are independent from individual thermal conductance. Further analyses will consider intra-seasonal variation in metabolic performance and ambient temperature.