Spatial scale dependence of rodent habitat use

Many insights into community ecology over the past 3 decades were derived f rom investigations of associations of rodent species with microhabitats. No netheless, studies of microhabitat use of rodents are inconsistent, suggest ing spatially dependent interacting factors. We investigated the relative a bility of microhabitat and macrohabitat to predict rodent captures in traps placed in 48 trapping grids of 90 traps each during spring and autumn of 1 993 and 1994 (17,280 data points). Trapping grids represented eight replica tions of six discrete macrohabitats. We used discriminant function analysis and random null models to compare the ability of microhabitat and macrohab itat to predict use of individual traps by 13 rodent species. Classificatio n rates for presence at a trap by dummy variables of macrohabitats exceeded those obtained with principle components of microhabitats for nine of 13 s pecies. In seven of those cases, classification rate exceeded that expected from a random distribution of dummy variables. Of the four cases where pri nciple components of microhabitats out-classified dummy variables of macroh abitats, only two exceeded rates expected from a random distribution of dum my variables. Thus, microhabitat partitioning for many species is constrain ed by local macrohabitat conditions.