Geographic variation in the frequency of scarring and tail stubs in eastern gartersnakes (Thamnophis s. sirtalis) from Michigan, USA

Tail loss, urotomy, in reptiles and amphibians has been the emphasis of many ecological and evolutionary studies, especially in lizards and salamanders; however, less is known about this phenomenon in snakes. In addition, while hypotheses for variation in tail loss across natural populations exist, none have been strongly supported. We conducted much needed research on tail loss in snakes and attempted to elucidate any relationship between variation in predator composition and frequency of wounds. 523 common gartersnakes, Thamnophis sirtalis, from 5 Michigan, USA field sites characterized by diverse predator compositions were examined for tail loss and other predator-inflicted wounds and historical records of predator composition for Michigan were updated. Our results indicate that frequency of wounds vary geographically, and that this variation may be due, in part, to differences in predator diversity. Our data also suggest that other environmental variables (e.g., predator inefficiency) that may influence the frequency of wounds in populations may be at work.