Toad Fencing

Controlling toad movement

It was estimated in 1998 that 1 million vertebrates were killed every day on roads in the United States, a high proportion of them being amphibians, frogs, toads, and salamanders. Given the increase in traffic volumes since then, this figure – when replicated globally – shows what a serious problem road-kill is, with additional deaths occurring at unfenced development sites and railroads. For salamanders, most deaths come during their migration between breeding sites (they require an aquatic environment to breed) and terrestrial feeding or hibernation sites.

Salamanders and newts exhibit site fidelity, which means they return to the same vernal pool(s) each spring to breed, very often the pool(s) where they were born. In many parts of the world that means having to cross roads to get there – and they’re not good at avoiding traffic. In one Canadian study, biologists found that there had been more than 30,000 amphibian deaths in four years on a 3-kilometre stretch of road. Other researchers found that in western Massachusetts, road-kill rates were high enough to lead to localized extinctions of Spotted Salamanders (Ambystoma maculatum) in 25 years. Additionally, any construction site is also a potential death trap for amphibians, hence the need for effective exclusion fencing.

It is the responsibility of transport planning engineers to reduce the ecological impact roads have and use mitigation measures as tools in ecological conservation. Fencing, along with other mitigation measures, such as tunnels, has been shown to reduce road-kill dramatically at key migration points without disrupting the animals’ life cycle. However, it has to be the right kind of fencing or salamanders will find a way through it, rendering it a waste of time and money.

Fencing can also be used to aid population assessment before the development of new construction sites.