Morphology, reproduction, habitat use, and hibernation of Red-bellied Snake (Storeria occipitomaculata) near its northern range limit

Northern regions limit ectotherms to relatively short periods of feeding and breeding interrupted by long periods of inactivity. This may force cool-climate ectotherms into different ecological or demographic trade-offs than their southern conspecifics. Our aim is to examine demography, morphology, reproduction, habitat use, and hibernation by populations of Red-bellied Snake (Storeria occipitomaculata) near their northern range limit. This research was conducted in southwestern Manitoba and data on summer activity were collected from April to September 2007–2009 using coverboard and pedestrian surveys. Hibernation sites were monitored over three winters (2007–2008, 2008–2009, and 2009–2010), and thermal profiles of Formica ant mounds were collected in 2008–2009 and 2009–2010. Females reached sexual maturity at a smaller size than most other populations that have been reported but appear to have similar clutch sizes to the rest of the range. The majority of adult females captured at our summer sites were gravid (96%) suggesting annual reproduction, and activity patterns suggest fall breeding. Near its northern range maxima, this species appears to use relatively warm habitat, have rapid reproduction, and co-opt ant mounds to survive in a difficult climatic environment. Much remains unknown and future studies should further examine the variation in size at maturity and the relationship between body size and clutch size. In addition, little is known about diet, benefits of fall mating, use of open prairie habitats, and late-season migration by S. occipitomaculata