Meeting Abstract
P3.30 Monday, Jan. 6 15:30 Migration to summer feeding grounds is associated with changes in plasma glucocorticoids and glucose in red-sided garter snakes (Thamnophis sirtalis). MAINE, AR*; DAYGER, CA; RICHARDS, DY; RAMIREZ, LM; LUTTERSCHMIDT, DI; Portland State University, Oregon d.lutterschmidt@pdx.edu
Transitions between life history stages are often characterized by dramatic switches from one behavior mode to another and include examples such as reproduction, migration, and foraging. The neuroendocrine mechanisms that regulate these behavioral transitions, however, are poorly understood. We previously showed that male red-sided garter snakes (Thamnophis sirtalis) dispersing to summer feeding grounds have significantly lower baseline corticosterone concentrations than courting males at the den. Because sex differences exist in both the timing of dispersal from the den and activation of feeding behavior, we asked whether intra-seasonal changes in plasma corticosterone and/or glucose differ between male and female snakes. Snakes were collected from the den or a road along their migratory route, approximately 1 km from the den; blood samples were collected immediately upon capture. Both male and female snakes collected from the den had significantly higher baseline corticosterone compared to dispersing snakes (P < 0.001). In contrast, dispersing snakes had significantly higher glucose concentrations than den-collected snakes, suggesting that the activation of foraging behavior is linked to dispersal from the den. However, den-collected female snakes had significantly lower glucose concentrations than those of den-collected males (P = 0.003), suggesting that changes in blood glucose alone do not induce migration and/or foraging behavior. We are currently examining whether seasonal changes in neuropeptide Y are associated with the switch between reproduction and foraging behavior in garter snakes. These data will provide insight into the neuroendocrine mechanisms that regulate life history transitions.
