Eurasian beavers (Castor fiber) behavioral response to simulated territorial intruders

Eurasian beavers (Castor fiber) live in family groups that defend territori es against other conspecifics. Part of this territorial defence involves co nstructing scent mounds near the stream bank within territories and marking them with castoreum, a urine-based fluid from the castor sacs, and (or) an al-gland secretion. The aim of this study was to test the hypothesis that E urasian beavers show one or more forms of territorial behavior when an intr uder, simulated in the form of experimental scent mounds (ESMs), has scent- marked inside the territory. We predicted that beavers would show a stronge r response to ESMs with castoreum than to those without. Results showed tha t 85% of all beaver fami lies (N = 20) made one or more behavioral response s to ESMs marked with castoreum from foreign adult males, whereas no ESMs p resented without castoreum received a response. We therefore conclude that a main function of territorial marking by beavers is to advertise spatially related dominance status, thereby providing opportunities for intruders to assess the presence of the owner and reducing the cost and risks of agonis tic conflict for both the owner and intruders. Additionally, it appears to be the scent emitted from an ESM and not the sight of it to which beavers r espond.