Researching small animals in traffic: "The results can have immediate benefits"

“It’s about both preserving species and reducing the number of traffic accidents,” says Rune Sørås.

Less than a year ago, he moved to Uppsala from Trondheim in Norway. There, he had recently completed his PhD with a dissertation on how bats cope with cold climates at the Norwegian University of Science and Technology, NTNU. In Sweden, he was attracted by a project within the framework of the Swedish Transport Administration’s research program Triekol, run in collaboration with the SLU Swedish Biodiversity Centre. The program’s overall purpose is to develop methods and knowledge so that the transport sector can maintain, and if possible improve, the ecology in the landscapes around our roads and railways. 

“It’s exciting to be part of research that has a direct value for how we manage nature. The Swedish Transport Administration is engaged and interested in what we find out – and they act on the research,” says Rune Sørås.

Culverts can reduce wildlife mortality

Busy roads create barriers for animals searching for food or mates. Crossing a road can also be the last thing they do in life. Dead badgers, foxes, hedgehogs, and other animals are a common sight along our roads.

Earlier research within Triekol has focused on larger animals such as moose and deer. There, the best protective measures are often controlled crossing points and wildlife fences. However, fences do not stop small and medium-sized animals – such as hedgehogs, squirrels, hares, rabbits, otters, badgers, and foxes.

Culverts exist regardless to divert water away from the road.

These are the ones Rune Sørås is now focusing on.

“Under many roads there are culverts, which are also used by smaller animals,” he explains.

“Culverts are there anyway to divert water from the road. With more knowledge about how they are used, they can be designed and placed in ways that facilitate crossings.”

In his research project, Rune Sørås will compile and analyze existing data on how animals move and are killed in traffic. Among other things, he has access to a large dataset where foxes have been tracked with GPS. He is also conducting his own fieldwork.

40 cameras record activity

In the fieldwork, Rune Sørås is using more than 40 wildlife cameras, which he has placed along both larger and smaller roads – mainly in Uppsala and Örebro counties. Just the other day, he was out repositioning some of them.

“There is quite a bit of driving and walking,” he says.

By placing cameras at different types of culverts, Rune Sørås can see which ones are mostly used. Do elements of the surrounding landscape, like proximity to forest or watercourses, affect usage? Does it matter if the culvert is wide or narrow? Long or short? Filled with water or dry? What role does the location of the culvert’s entrance play?

“If the opening is at the same level as the road, one theory could be that it’s just as easy to cross a less busy road – for a fox, for example,” he says.

“If, on the other hand, the road is much higher than the culvert, then the culvert might be the easiest route.”

Proposing an umbrella species

The Swedish Transport Administration does not have the resources to adjust for every animal. A result of the research could therefore be to propose a new so-called umbrella species for small and medium-sized animals. By focusing on the needs of such a species, other sensitive species can also be protected.

“Perhaps there is a better umbrella species that covers the needs of several animals,” says Rune Sørås.

So far, the otter, which was once listed as endangered but has now recovered, has received the most focus. There are special otter passages over some drainage culverts.

“It’s not wrong to keep track of the otter, but maybe there is a better umbrella species that includes the needs of several animals,” Rune Sørås says.

Hedgehogs are vulnerable

No matter which umbrella species is chosen, one animal risks being left out. The red-listed hedgehog often moves near settlements where wildlife cameras are not placed, and it is frequently run over.

“We need to know more about it,” says Rune Sørås, hoping there might be a continuation of his current research at the SLU Swedish Biodiversity Centre.