Improving conservation translocation and ex situ breeding techniques for the recovery of a temperate zone rattlesnake

Abstract

Reintroduction biology is the study and practice of establishing populations of organisms using tools like conservation translocation. An understanding of how to effectively conduct translocations, particularly with snakes, is lacking and there is a need for technique improvement. Systematic literature review, occupancy modeling, artificial hibernation, retrospective analysis of zoo data, and population viability modeling were used to evaluate the effectiveness of in situ and ex situ techniques to inform future translocations with temperate zone snakes. Field work occurred at the Ojibway Prairie Complex and Greater Park Ecosystem in southern Canada with the Eastern Massasauga (Sistrurus catenatus), a rattlesnake in decline across its global range and in need of research into the effectiveness of population management tools. When working with a low detectability species, results showed that evaluating long-term success of translocations at achieving population establishment requires intensive survey efforts to estimate patch occupancy across a study landscape. In the short-term, the invasive and sample- size-limiting technique of radiotelemetry is required for evaluating success of release tactics. A systematic literature review on snake translocations provided evidence for the utility of a suite of translocation tactics for reducing postrelease effects. However, an assessment of ex situ reproductive output coupled with demographic modelling, showed that certain beneficial tactics (e.g., release of captive-reared snakes) can be problematic to implement and sustain, perhaps due to breeding techniques that fail to replicate natural conditions, and with potential impacts to release site fidelity of translocated snakes. Empirical and theoretical guidance were provided for Massasauga recovery by informing eight steps for a successful snake translocation, beginning with the establishment of translocation goals and ending with effectiveness monitoring. Regardless, recovery efforts are hindered by the limitations of existing ex situ breeding techniques, coupled with intensive supplementation efforts required to overcome postrelease effects in situ and to establish a viable wild population over time. Research into alternative ex situ breeding techniques for viperids (e.g., polygamous matings) and effectiveness of beneficial translocation tactics for snakes in general are required. Reintroduction can be a daunting and resource intensive pursuit, echoing the need to stabilize declining populations before they become small.