Meeting Abstract
Snow buntings (Plectrophenax nivalis) are arctic breeding migratory passerines that spend their winters on exposed snowy and windy plains of southern Canada. Although these cold environment specialists migrate “south” for the winter, they are nevertheless exposed to relatively harsh wintering conditions that are known to require significant increases in metabolic performance in resident species wintering at the same latitudes. In this study, we tested whether outdoor captive snow buntings would respond to winter conditions by expressing physiological changes typically seen in northern resident species. From November 2013 to April 2014, we measured body mass, muscle size, fat score and metabolic performance (maximal thermogenic capacity, and basal metabolic rate) once a month on 15 individuals. Results indicated that birds increased fat reserves and muscles size during the coldest months, as would be expected in resident species having to support cold conditions through shivering thermogenesis. However, changes in metabolic performance were not those expected. Basal metabolic rate did not change significantly over the course of the winter, suggesting little influence of temperature on physiological maintenance costs. Thermogenic capacity changed between months but did not show a seasonal increase culminating at the peak of cold as typically found in wintering non-migratory species, perhaps as a result of good thermal insulation from the plumage.
