Population density of the Eurasian beaver (Castor fiber L.) (Castoridae, Rodentia) in the Middle Volga of Russia

The article presents research on the population density of the Eurasian beaver in the large, medium and small rivers of the Republic of Mordovia. The population density of the beaver in the large rivers of the region varies from 0.45 to 0.62 colonies per km (average 0.52). The population density in medium rivers ranges from 0.36 to 0.48 colonies per km (average 0.4). In small rivers, population density ranges from 0.2 to 0.94 colonies per km (average 0.46). The total number of beavers in the region is about 17,000 individuals as at 2016.