Wednesday, July 16, 2014

Moving Massasaugas

Relocating animals is a commonly used conservation technique. In the case of venomous snakes, relocation is often prompted by the potential for negative human-snake interactions. However, other reasons to relocate snakes include the re-establishment of extirpated populations, the establishment of new populations of imperiled species in more suitable locations, and augmentation of imperiled populations.
            The varied outcomes of studies done on snake relocation suggest the technique remains an experimental rather than an established conservation method for snakes. The diverse outcomes reflect the fact that relocation is not a single technique, but a collection of techniques that vary according to the extent of displacement and the source of relocated individuals (wild or captive-born). When snakes are moved short distances, such as might occur when a “nuisance” snake is moved away from the point of conflict, homing behavior can result in the snakes simply returning to the area from which they were moved. Short-distance translocation (i.e., relocation of wild animals within their home range) may also cause snakes to alter their behavior in ways that increase mortality in some cases, but not in others.
            In a new study, Harvey et al. (2014) conducted two types of relocation (repatriation and short-distance translocation) using Eastern Massasaugas (Sistrurus c. catenatus) in Ontario. For the repatriation experiment, 27 snakes were captive-born, raised for four years, and released into a nature reserve previously known to host massasaugas. Other than being relatively sedentary, snakes behaved normally upon release in that they engaged in reproductive behavior. Survival was relatively high at 70% until hibernation (19 weeks). However, none of the snakes that did hibernate (n = 19) survived into the following active season.
            In a preliminary assessment of the effects of short-distance translocation, snakes that the researchers moved 200 m from capture locations (n = 4) did not return, nor did they exhibit abnormal movement or basking behavior relative to non-translocated controls (n = 7). The different outcomes of our two relocations could indicate that the success of relocation depends on the extent of displacement and the source of relocated individuals, although corroborating evidence is needed before these results can be used to support management strategies.

Citation

Harvey, DS, Lentini AM, Cedar K, PJ Weatherhead. 2014. Moving massasasauguas: insight into rattlesnake relocation using Sistrurus c. catenatus. HerpetologicalConservation and Biology 9:67-75.

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