Evaluating conservation strategies for a threatened population of gray ratsnakes (Pantherophis spiloides)

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Macpherson, Matthew
Conservation Biology , Animal Behaviour , Herpetology
Wildlife populations across the globe are declining due to the effects of increasing anthropogenic activities. Among the most vulnerable taxa are snakes, which face several threats including road mortality and habitat loss. To combat such threats, several different conservation techniques have been implemented. Roadside barrier fencing is designed to reduce adult mortality by preventing snakes from accessing the road, while artificial nesting sites serve to increase recruitment. Despite their growing use, however, these strategies are seldom rigorously tested before or after implementation. In this study, I examined the effectiveness of roadside barrier fencing and artificial nest boxes for gray ratsnakes (Pantherophis spiloides), a species at risk in Canada. The goals of my research were to (1) determine the fencing design that prevents gray ratsnakes from successfully climbing over, and (2) determine the environmental variables that influence the use of nest boxes by gray ratsnakes. To do this, I captured and placed gray ratsnakes within fencing enclosures composed of different heights, materials, and shapes commonly used in roadside barrier fencing. I then measured whether or not snakes were able to escape, as well as different behavioral responses. I also placed nest boxes throughout various habitats and monitored their environmental conditions throughout the incubation period before checking them for snake eggs. My study revealed that fence material played a significant role in whether or not a snake could climb it, and found a significant interaction between height and shape on snake climbing success. Further, I found that snakes were less willing to climb fencing that was higher and made out of hardware cloth than vinyl sheeting. I also found a near-significant relationship between whether or not a nest box was used and a combination of internal temperature, moisture, and canopy cover. Nest boxes that were used featured higher internal temperatures, moisture, and mid-range canopy covers; however further investigation is needed due to lack of power given the small sample size. My study highlights the importance of identifying and rigorously investigating knowledge gaps surrounding conservation strategies, to maximize their effectiveness and avoid wasting already-limited conservation funding.
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