Factors influencing the emergence of a northern population of Eastern Ribbon Snakes (Thamnophis sauritus) from artificial hibernacula

We investigated whether Eastern Ribbon Snakes (Thamnophis sauritus (L., 1766)) use a rise in water level as a cue for emergence from hibernation. We also examined the hypotheses that snakes use temperature gradients or endogenous signals as emergence cues. Twelve artificial hibernacula were used to house 15 Ribbon Snakes. Water level and temperature were regulated. Four Ribbon Snakes emerged from hibernation without any manipulation of water level or temperature. Eight snakes emerged after thermal conditions in their hibernacula changed. Of these, one emerged after the hibernaculum was made warmer on the surface than at depth, four emerged after the room temperature was increased to 9°C, and three emerged after incandescent lights were shone on the surface of each hibernaculum. Three snakes died during hibernation. Eight snakes chose to hibernate fully submerged in water. Although the sample size is too small to draw conclusions that are statistically significant at α = 0.05, our observations collectively suggest that Ribbon Snakes do not use a rise in water level as a cue to emerge. While water-level rise does not appear to be an emergence cue, hibernation below the water table may lead to increased survivorship by decreased metabolism and elimination of the risk of desiccation. Nous cherchons a savoir si les couleuvres minces (Thamnophis sauritus (L., 1766)) utilisent l'elevation du niveau d'eau comme signal pour l'emergence de l'hibernation. Nous examinons aussi les hypotheses selon lesquelles les couleuvres utilisent des gradients thermiques on des reperes endogenes comme signaux d'emergence. Douze hibernacles artificiels ont servi a loger 15 couleuvres minces. Le niveau d'eau et la temperature y etaient contreles. Quatre couleuvres minces sont sorties d'hibernation sans aucune manipulation du niveau d'eau ni de la temperature. Huit couleuvres ont emerge apres que les conditions thermiques de leur hibernacle eurent change. Parmi celles-ci, une a emerge apres que son hibernacle ait ete rechauffe plus en surface qu'en profondeur, quatre apres que la temperature de la piece ait ete elevee a 9°C et trois apres que la surface de leur habitacle ait ete eclaire par des ampoules lumineuses incandescentes. Trois couleuvres sont mortes durant l'hibernation. Huit couleuvres ont choisi d'hiberner completement submergees dans l'eau. Bien que l'echantillon soit trop petit pour en tirer des conclusions statistiquement significatives a α = 0,05, nos observations globales laissent croire que les couleuvres minces n'utilisent pas le niveau d'eau comme signal de l'emergence. Meme si 'augmentation du niveau de 'eau ne semble pas etre un signal pour l'emergence, l'hibernation sous le niveau de la nappe phreatique pent augmenter la survie en diminuant le metabolisme et en eliminant le risque de dessiccation. [Traduit par la Redaction]
Introduction Reptiles that live at high latitudes have a much shorter active season than reptiles at lower latitudes. In regions where freezing occurs, a clear signal of when to emerge [...]