Thermal Ecology of the Eastern Massasauga (Sistrurus catenatus) in Northern Michigan

The ability of ectothermic organisms to properly thermoregulate at optimal temperatures influences many aspects of their life histories, including fundamental physiological processes such as digestion, patterns of movement and habitat selection. We studied the thermoregulatory behavior of Eastern Massasaugas (Sistrurus catenatus) in northern Michigan during 2006, 2007 and 2013 to determine if and when massasaugas thermoregulate within their preferred body temperature range and the accuracy to which they do so throughout the activity season. Using radio telemetry, snakes were tracked during daylight hours, and several thousand internal body temperature measurements of 48 individuals over the course of three field seasons were obtained. Massasaugas thermoregulated more accurately and at temperatures closer to or within their preferred range during spring and summer compared to fall, where snakes were unable to reach temperatures at even the lower end of the preferred range. The general daily trend was for the body temperatures of snakes to rise closer to or at preferred levels by mid-morning through mid-afternoon, and then cool below the preferred range into evening. The Eastern Massasauga is a protected species throughout its range due to loss of suitable habitat and persecution. Further investigation of how behavioral thermoregulation relates to habitat selection by massasaugas can help guide landscape management decisions, and thus enhance conservation measures for this imperiled species.http://opus.ipfw.edu/stu_symp2014/1069/thumbnail.jp