Scientists have discovered that re-introducing beavers into an area is good for bats. The rodents bring down trees, so that a bat has to avoid fewer obstacles. In addition, beavers create large water features with their dams that attract insects - food for bats. The influence of the beaver therefore extends beyond what was thought.
Beavers change an area considerably. They determine the flow of waters and can bring down large trees. Scientists had previously shown the effects of all that hard work, but focused primarily on aquatic animals. It was assumed that these would be most influenced by the beaver. But Polish scientists decided to look a lot further.
In the nineteenth century the beavers in the northern part of Poland died out en masse. Between 1943 and 1986 the Poles re-introduced the beaver. The researchers looked at what effect that had. They discovered that especially the bats that used insects benefited from the return of the beaver.
"Bats are very good kites, but the species that get their prey from the air cannot hunt effectively in a dense forest," says researcher Mateusz Ciechanowski. The animals emit sounds and determine where the insects are based on the ultrasound. But in a forest with many trees, the sounds also bounce off trunks and branches. This causes the bat to become disorientated.
Beavers can help the bat to get rid of the trees. Moreover, the water pools that the beavers make with their dams attract many insects. The forests that had become more water-rich and, thanks to the beavers, also had fewer trees, had the largest number of bats.
Remarkably, bats that live close to the water benefit less from the work of the beavers. They track down their prey by releasing sounds on the water and listening to the echo. But the dams of beavers produce a confusing echo, as a result of which the animal does not know whether it has encountered insects.
According to the scientists, their study shows how important beavers are for a forest. “It supports the reintroduction of beavers. Not only for the animal itself, but also as a means to restore the habitats that we have destroyed ourselves. "