Meeting Abstract
Animals express physiological and behavioural plasticity to cope with changes in food availability. Resting metabolic rate (RMR) is a highly plastic physiological trait defined as the basic energetic cost of survival. To explore whether individuals are more likely to sustain increases in maintenance costs when food availability is high, we compared food-supplemented and control populations of free-living North American red squirrels Tamiasciurus hudsonicus at the beginning of the breeding season. We found that measures of whole-animal RMR for supplemented squirrels were 16 percent higher compared to controls and 12 percent higher once differences in body mass were considered. Supplemented females were characterized by earlier parturition dates than controls. Two months following the removal of supplementary food, no difference in RMR was detected between food supplemented and control groups, though breeding females tended to maintain a higher RMR than non-breeding females and males. We conclude that breeding red squirrels are enabled to increase maintenance costs when food availability is high and that this response is reversible when sufficient food is no longer available.
