Barriers for big snakes: Incorporating animal behaviour and morphology into road mortality mitigation design

Abstract

To combat worldwide decline in biodiversity, many conservation strategies have been developed to counter anthropogenic threats. Among these is roadside barrier fencing designed to mitigate road mortality, a major threat to many terrestrial vertebrates. Few strategies are tested before implementation, however, and in some cases mitigation either fails to alleviate or even exacerbates road mortality. Moreover, mitigation often fails to account for inter- and intraspecific differences in morphology and behaviour, or the influence of different aspects of structural design. We assessed the effectiveness of multiple barrier fencing configurations differing in design and materials on the behavioural response of gray ratsnakes (Pantherophis spiloides). Fencing material had a significant influence on the likelihood of a ratsnake successfully climbing over the fencing. Further, we found a significant interaction between fencing height and shape on the likelihood of a ratsnake successfully climbing over the fencing. Longer snakes were more successful at climbing over fencing than shorter ones. The most effective fencing tested was 100 cm metal mesh fencing with a lip, which prevented successful escapes in 93.3% of trials. Fencing material and height also influenced the number of climbing attempts per minute made by the ratsnakes. Our study highlights the importance of including structural attributes and morphological variation within a species before deploying a conservation strategy. Moreover, our results show that understanding the behaviour of a target species can enhance prospects for success and limit costs of mitigation strategies.

Keywords

• Barrier fencing
• Road ecology
• Reptiles
• Animal behaviour