Timothy Gleeson was a BSc Animal Behaviour student at the time of his research, which has been recently published in Bioscience Horizons.
Timothy was supported by his Lecturer, Dr Anna Muir, Programme Leader for Conservation Biology at the University, and the research was carried out in collaboration with Froglife (a national amphibian and reptile conservation charity), through Dr Silviu Petrovan, a Research Associate in the Department of Zoology at the University of Cambridge.
Froglife is a national wildlife charity committed to the conservation of amphibians and reptiles – frogs, toads, newts, snakes and lizards – and saving the habitats, on which they depend. Froglife says that there has been a catastrophic decrease in toad populations - with common toads declining by 68% over the past 30 years.
In this study, the University of Chester collaborated with the charity to assess how rainfall affects the use of under-road tunnels by amphibians.
Road mortalities are a major source of death in amphibians and can lead to population decline. According to Froglife, it’s estimated that 20 tonnes of toads are killed on the UK’s roads every year. Reduction in population numbers, as a result of being run over by cars, has particularly been observed in common toads, which always return to the same pools to breed, even when dispersal routes are blocked by roads.
One way to mitigate the effect of roads on amphibian migration routes, is to install under-road tunnels or culverts, so that frogs, toads and newts can pass safely underneath. However, how the weather impacts the use of these culverts by amphibians is not well understood.
As part of research aiming to address this, this study used images obtained by Froglife from custom-made, time-lapse camera traps placed within under-road culverts. Images recorded movement within a culvert adjacent to a Scottish loch by common toads, common frogs, smooth newts and palmate newts during the autumn migration. Movement behaviour was compared to recent rainfall data from a local weather station.
As the time since the last rainfall increased, common toads and common frogs used the culvert less. This may have been caused by the culvert not maintaining wet enough conditions for amphibians.
Dr Anna Muir said: “This study highlights the importance of investigating the effectiveness of mitigation measures and considering the ecological requirements of animals that use under-road tunnels. Timothy has shown great commitment to his research and I’m delighted that he has succeeded in producing such interesting results that have direct conservation implications.”
Timothy Gleeson said: “I am very happy to see this research published. It is very worrying to see amphibian populations declining. Humans are contributing to this decline by building roads that intersect amphibian migration and dispersal routes and it is important that we do as much as we can to minimise our impact and to help save amphibian populations. This research suggests that designing culverts so that they hold water for longer will help maintain favourable conditions and could allow culverts to be more effective at mitigating the effect of roads on amphibians."
Dr Silviu Petrovan added: “It is great to see students’ work contributing to a better understanding of real conservation problems and potential solutions. Temperature and humidity play important roles in amphibian movements and their impact on road mitigation structures is something that requires careful consideration. Deploying road tunnels that maximise usage and effectiveness for their target species could have real benefits in reducing negative impacts from roads.”
