USE OF TREE CAVITIES BY FOX SQUIRRELS AND RACCOONS IN INDIANA

We investigated interspecific relationships between fox squirrels (Sci urus niger) and raccoons (Procyon lotor) through a comparison of use o f dens in winter at Muscatatuck National Wildlife Refuge in southcentr al Indiana, January-March 1984-1985. Fox squirrels selected dens with smaller entrances and volumes; dens of squirrels were located greater distances from water than cavities used by raccoons and unused cavitie s. Dens occupied by fox squirrels had smaller entrances and shorter di stances to forest openings than cavities previously used by fox squirr els, but unoccupied when examined. Den sites of raccoons did not appea r to be a limiting resource in winter because of a large number of unu sed cavities. Raccoons were not important competitors for cavities use d by fox squirrels, but squirrels selected maternal or rest sites that could restrict vulnerability to predation by raccoons by limiting acc ess to cavities. Selection of den sites relative to thermoregulatory c osts also could influence choice of dens by fox squirrels.