Dispersal and Survival of Juvenile Beavers (Castor canadensis) in Southern Illinois

TLDR: Survival during dispersal was greater for beavers emigrating from lodges on the land-locked, less densely populated site than for those dispersing in an area of higher population densities, but did not differ between dispersers and non-dispersers at either site.

Abstract: We used radiotelemetry to estimate natal dispersal patterns and survival rates of 13 yearling and 19 subadult beavers (Castor canadensis) at two geomorphologically different sites in southern Illinois. Overall, we observed a 55% dispersal rate for yearlings and a 73% dispersal rate for subadults. Normally, juveniles (yearlings + subadults) initiated dispersal around 16 February (range = 28 Jan.–20 Mar.) and settled around 18 April, with juveniles remaining transient from late January through late June. Nine subadult beavers dispersed significantly earlier at one site (x = 25 Nov., range = 31 Oct.–16 Dec.), presumably due to intra-colony strife brought on by management-induced autumn flooding of wetlands for waterfowl. Dispersal occurred earlier than documented in northern regions. Beavers dispersed farther from natal colonies with free-flowing water access (x = 5.9 km) than those landlocked (x = 1.7 km). Males moved more frequently and traveled greater distances per individual move than did fe...