Selection of mast by granivorous rodents of the central hardwood forest region

We used cafeteria-style feeding trials with 8 types of mast in various comb inations to examine differences in resource selection among 5 syntopic spec ies of granivorous forest rodents in west-central Indiana. Patterns of reso urce selection corresponded to differences in phylogeny and body size of gr anivores, with greatest similarities among closely related species of simil ar body size. Breadth of resource use varied inversely with body size in ou r trials, Resource selection by Sciurus carolinensis, S. niger, and Tamiasc iurus hudsonicus was correlated positively with caloric and lipid content o f mast and its size, whereas selection by Glaucomys volans was correlated n egatively with the percentage of protective tissue associated with seeds. L aboratory trials indicated that T. hudsonicus and G. volans discriminate am ong mast of comparable physical and chemical composition on the basis of si ze, with a preference for larger seeds. Contrary to our expectations, T. hu dsonicus, a recent immigrant from the boreal forest, did not exhibit a pref erence for seeds of red pine (Pinus resinosa) relative to mast of hardwood species. G. volans and Peromgscus leucopus tended to consume perishable whi te oak acorns immediately and to cache a substantial portion of less perish able seeds of nonpreferred species. Our results demonstrate the potential f ur considerable overlap in resource use among members of this guild. Guild members also seem to be affected differentially by physical and chemical pr operties of mast, and patterns of resource selection reflect contrasting fo raging constraints under which these animals operate.