Effectiveness and efficiency of temporary fences as mitigation measures for preventing amphibians roadkill

Abstract

Temporary fences are used to prevent amphibians from accessing dangerous areas. These fences can be built out of different materials and field studies have shown that some of them still allow for trespassing. In this study we compared, in controlled conditions and using experimental arenas, the effectiveness and efficiency of the three most commonly used materials for temporary amphibian fences (polyethylene tarp, polyethylene netting, and wire meshing) and of the presence of an overhang, on two amphibian species with distinct modes of locomotion (walker/short-distance jumper; long-distance jumper). The polyethylene tarp fence, and fences equipped with an overhang, were the only designs able to stop every individuals for three consecutive trials. Fences that were not slick or equipped with an overhang could be crossed at any height by both species. For non-climbable fences, long-distance jumper species required a 60 cm high fence to be stopped while the walker/short-distance jumper species only required 20 cm. The walker/short-distance jumper individuals interacted 1.7 times more with the polyethylene netting and wire meshing than the polyethylene tarp, due to either differences in opacity between materials or the impossibility to climb on the tarp. The long-distance jumper species was not deterred by the tarp fence and interacted equally with all materials. When considering price, durability and ease of use while maintaining effectiveness, the polyethylene netting fences equipped with an overhang were the most efficient option for long-term use. Synthesis and applications: amphibian fences should systematically be equipped with a 10 cm overhang at their top to ensure their effectiveness. Polyethylene tarp is the best option for short-term use while polyethylene netting is the best option for long-term use.