Facebook post by University of Helsinki

In a study, beaver patches were found to host nearly twice the number of mammal species compared to forest pond patches not engineered by beavers. Particular increase of mammal activity was observed among otters, pine martens, weasels, and moose. Even the number of individual mammals was more than 10% higher in beaver sites.
The presence of beavers benefits also other mammals helsinki.fi

Petri Nummi has studied the environmental effects of beavers for almost four decades.