Date of this Version
THE SOUTHWESTERN NATURALIST 55(2):273–277
During a radio-tracking study of North American beavers (Castor canadensis) in Arizona, we discovered three adult, lactating beavers using the same bank den at the same time. Two adult females 5.2 kmdownstreamalso were using the same den at the same time. For the first case, we documented use of communal dens by lactating adults on seven occasions during 68 days. For the second case, we documented communaluseof adenonthreeoccasionsduring 45days.Totest the hypothesis that these communal females were closely related,weusedeight autosomalDNAmicrosatellites.Two females in thefirstdenwere first-order relatives. However, the other communal females were unrelated to the females with which they shared the den.We conclude that communal denning, wheremultiple females raise one ormore litters in the same den, may have occurred in our study area and communal-denning partners are, in some cases, close kin.