Microhabitat Use by Small Mammals in Central Chile

In evergreen shrubland, Akodon longipilis, A. olivaceus, Marmosa elegans, Oryzomys longicaudatus and Phyllotis darwini used areas under shrub canopies more frequently than openings between shrubs. Distribution of food resources, predation risk and the density of the herb layer combined to enforce this pattern. Shrub seeds, arthropods and predator refuges were more abundant in the underscrub. Small mammals responded to silhouettes of predators. Their few forays onto the open microhabitats occurred only during dark nights of autumn and early winter. A dense cover of exotic herbs from late winter to summer hampered movements. Food, predation and microhabitat structure were the proximate factors shaping selection of microhabitats, but human disturbance apparently was the ultimate factor. Disturbance: 1) reduces shrub cover, leading to increased predation pressure as the extent of uprotected areas increases; 2) creates a more patchily food distribution; and 3) favors invasion of exotic herb