Tail Loss Patterns in Thamnophis (Reptilia: Colubridae) and the Probable Fate of Injured Individuals

The frequency of tail loss in three species of Thamnophis was evaluated. Significant sex and size dependencies of tail loss were found in T. sirtalis and T. sauritus, but not in T. butleri. Tail loss was greater in females than in males, and generally increased with size. The frequency of tail loss was reduced in the 2529 cm size class. Because smaller, injured individuals must be preferentially eliminated from the population for this reduction in tail loss frequency to occur, we hypothesized that injured juveniles do not survive their first year, possibly due to hibernation stress. Alternately, injured snakes may emigrate or have injury-related behavioral changes which result in reduced frequencies of recapture. However, no injured snake less than a year old was recaptured after its first year; the frequency of injury of recaptured snakes in larger size classes was not different from the frequency of injury in original captures, further suggesting that injury in first year snakes results in death before the second year.