Effectiveness of wire netting fences to prevent animal access to road infrastructures: an experimental study on small mammals and amphibians

Abstract

Transport infrastructures, such as highways, disrupt animal migrations and cause roadkill. To mitigate the latter problem, fences have been built but their effectiveness has rarely been tested under controlled conditions. Here, we tested the effectiveness of the most commonly used fence in France and probably in Europe (wire netting fence) to block animals. We tested the wire netting fence, with and without a structural modification (i.e. an overhang), with three small mammalian species (the European hamster: Cricetus cricetus Linnaeus, 1758; the common vole: Microtus arvalis Pallas, 1778 & the wood mouse: Apodemus sylvaticus Linnaeus, 1758) and two amphibian species (the marsh frog: Pelophylax ridibundus Pallas, 1771 & the European green toad: Bufotes viridis Laurenti, 1768). During testing, all small vertebrate species tested were placed into an arena, from which they could only escape by crossing the wire netting fence. Without an overhang, almost all adult individuals of all tested species were able to climb over a 30 to 40 cm high wire netting fence. Furthermore, the addition of an 8 cm long overhang at the top of the fence stopped the amphibian species tested but not the most agile mammalian species, such as the hamster and the wood mouse. Based on these results, we do not support the construction of wire netting fences along roads as a measure to stop small animals from crossing. We recommend the use of more effective and durable fences, which, in addition, can be associated with wildlife passages to reconnect isolated populations.

Improving trajectories of amphibians in wildlife passages

“…Methodological developments (e.g., RFID, Testud et al, 2019;camera traps, Brehme et al, 2021;Conan et al, 2022) allow designing experiments to test for tunnel permeability and its link with individual behaviors, e.g., tunnel attractiveness including surroundings of the entrance and local conditions within the tunnel (substrates, open grated top to allow for natural light, temperature and moisture conditions). Knowledge about the probability of crossing a structure is also particularly relevant for friction map modeling and species distribution modeling at a regional scale in landscapes, which are often fragmented by linear transport infrastructure (Remon et al, 2018;Clauzel and Godet, 2020;Matutini et al, 2021).…”

“…The political agenda is often too shortsighted (Lesbarrères and Fahrig, 2012). The behavior of amphibians encountering a wildlife crossing (Matos et al, 2018) and fences (Brehme et al, 2021) has been rarely studied (Conan et al, 2022).…”

Ecological Solutions for Linear Infrastructure Networks: The key to green infrastructure development

“…Accommodating co-use by wildlife and humans may be possible when the mammal species are tolerant of human presence; however, wildlife passages intended to be used by species that are sensitive to human presence should avoid human co-use (Warnock-Juteau et al 2022). Commonly implemented wire netting fences are not efficient at stopping small animals from climbing over and onto the roadway, thus fences made of alternative materials (e.g., concrete, PVC) may be more efficient (Conan et al 2022). Short fencing segments can increase the risk of Florida Key deer (Odocoileus virginianus clavium) vehicle collisions, especially near fence-ends, thus mitigation measures must be implemented on an appropriate scale to be effective (Huijser and Begley 2022).…”

Best Practices Manual to Reduce Animal-Vehicle Collisions and Provide Habitat Connectivity for Wildlife

“…When crossing structures are not adequately spaced or there are not enough structures to match the movement distances of the target species, animals will either turn back or find a way to cross at-grade. While the impacts of roads on small mammal species may not appear problematic because their population densities are generally high, this is not always the case (Conan et al 2022). For instance, some European species are endangered and declining at an alarming rate, such as the garden dormouse (Eliomys quercinus) and the European hamster (Cricetus cricetus) and roadkill is important to address (Conan et al 2022).…”

“…While the impacts of roads on small mammal species may not appear problematic because their population densities are generally high, this is not always the case (Conan et al 2022). For instance, some European species are endangered and declining at an alarming rate, such as the garden dormouse (Eliomys quercinus) and the European hamster (Cricetus cricetus) and roadkill is important to address (Conan et al 2022). Well intended mitigation of barriers and crossing structures, can also lead to a population crash for amphibians such as the common toad (Bufo bufo) if the number of crossing structures is insufficient and keeps a sizeable portion of the population from moving between winter and breeding habitat (Ottburg & van der Grift 2019).…”