STUBBLEFIELD, K.*; ULTSCH, G.R.; SECOR, S.M.; University of Alabama, Tuscaloosa; University of Alabama, Tuscaloosa; University of Alabama, Tuscaloosa: Metabolic and Intestinal Response to Hibernation for the Eastern Garter Snake, Thamnophis s. sirtalis

Ectotherms in northern climates hibernate for up to seven months, during which time they do not feed. Considering the selective pressure to reduce energy expenditure during hibernation, the highly plastic nature of the intestinal tract, and the precedence for intestinal down-regulation for mammalian hibernators, we investigated the metabolic and intestinal response to artificial hibernation of the eastern garter snake, Thamnophis s. sirtalis. Garter snakes, collected in Minnesota, were artificially hibernated at 4�C for six months, during which time they did not lose body mass. Standard metabolic rates (SMR) of garter snakes decreased with decreasing temperature, dropping by 95% from 30 to 5�C. Over the six months of hibernation, SMR of garter snake at 5�C declined by 20%. At one to two month intervals snakes were removed from hibernation and we measured small intestinal mass and rates of nutrient uptake (everted sleeve technique). Within several months of hibernation, garter snake small intestinal mass had declined by 25% and mass-specific rates of amino acid uptake had decreased by 50%. This decrease in mass and function generated a combined 65% depression of intestinal performance. The concurrent depression in metabolism and intestinal performance suggests that garter snakes downregulate intestinal performance during hibernation as a selective mechanism to conserve energy and increase overwinter survival.