Environmental influences on the hibernation patterns of Eastern woodchucks (Marmota monax) [Facteurs environnementaux sur les canevas d\'hibernation des marmottes orientales (Marmota monax)].

Résumé

Animals enter hibernation to cope with low environmental temperatures and lack of food resources. However, we know little about the flexibility of hibernation physiology, i. E., how differences in environmental conditions affect hibernation patterns within a species. Woodchucks (Marmota monax) occupy a wide geographic range, thus experience a wide range of ecological conditions. We would expect these mammals to vary in hibernation patterns depending on latitude. We collected body core temperatures (Tb) on a continuous basis from free-ranging woodchucks during 3 hibernations seasons from fall 2005 to a spring 2008 at field locations in Maine (43°42’N; 70°14’W), Pennsylvania (40°22’N; 75°22W), and South Carolina (33°26’N; 81°20’W). We surgically implanted iButton temperature data loggers into animals from each location (11 in ME, 12 in PA, 8 in SC). We released them at the site of capture and recaptured them at the end of each hibernation season to recovers the loggers. During the winter of 2007-08, two animals from each location were captured and maintain in the lab under constant temperature conditions. In the field, ME, animals spent 88 % of the time torpor; in PA 80 %, and in SC 70 %. Dates of first torpor and final arousal, number of torpor bouts, length of torpor and euthermic bouts, and torpor TB\’s also differed significantly across populations. Lab animals from the 3 locations exhibited both similarities and dissimilarities in hibernation patterns to their home counterparts. These results reflect the flexibility of hibernation under different environmental conditions and the relative influence of environmental verses genetic factors on hibernation patterns.