Jan 17

Reintroduced beavers construct the ideal habitat for bats, according to new research.

By felling trees to create the dams in which they live, reintroduced European beavers actively manage their habitat by thinning out the canopy. This leaves fewer obstacles in the way of aerial-hunting bats as they pursue insects.

River-damming by beavers also boosts the numbers of their insect prey by creating large waterlogged areas.

Scientists say this study provides further evidence of beavers’ essential role in maintaining woodlands.

Photo of Eurasian beaver diving

More like a marine than terrestrial mammal, beavers have webbed hind feet and a flattened, scaly tail that provides steering and propulsion.

Beavers are known to extensively transform the environments in which they live by felling trees for food and building dams. But it was previously unknown how beavers can affect species living on or in the water.

So researchers from the University of Gdansk, Poland aimed to study the effects of beaver activity on species less obviously connected to wetland habitats.

Photo of Eurasian beaver swimming at surface of water

European beavers actively manage their habitat by felling trees to create dams and ponds in which they live.

In findings published in the European Journal of Wildlife Research, Mateusz Ciechanowski reports benefits for insectivorous bats sharing habitat with beavers. “Forest that was both flooded and subjected to beaver ‘logging’ supported the highest bat activity”.

Aerial-hawking bats, including common pipistrelles (Pipistrellus pipistrellus), Nathusius’ pipistrelles (Pipistrellus nathusii), soprano pipistrelles (Pipistrellus pygmaeus) and common noctules (Nyctalus noctula), appeared to benefit the most from beaver activity.

Aerial-hawking bats hunt by echo-location, bouncing sound off their prey and listening for the echo, which identifies its location. In dense forest the echoes of insect prey are “cluttered” by echoes from branches, making hunting less effective. But in areas where beavers have felled trees, aerial-hawking bats capitalise on the canopy gaps to catch more prey.

Photo of Eurasian beaver den in typical wetland habitat

A European beaver den in typical wetland habitat.

Mr Ciechanowski believes this study complements conservationists’ arguments that beavers are an essential or ‘keystone’ species in woodland habitats. “It simply supports the idea of beaver reintroduction… not only for that magnificent animal itself, but also as a tool to restore habitats biologically depauperated by ourselves.”

Find out more about this study by reading the BBC article.

Explore more Endangered species on ARKive.

Alex Royan, ARKive Species Text Author