The effect of topography on the foraging costs of heteromyid rodents

We investigated variation in perceived foraging costs to kangaroo rats (Dip odomys spp.) along a topographical gradient in the Chihuahuan desert. We us ed resources left in experimental seed trays to assess these costs. Both th e proportion of trays in which Dipodomys foraged and the giving up densitie s of seeds in the trays decreased with elevation on hillside transects. The se results suggest that kangaroo rat foraging activity was greater, with mo re trays encountered, at the bottom of the hills; however, microhabitat for aging costs (predation risks) were lower, yielding lower giving up densitie s of seeds in trays, at the tops of the hills. (C) 2001 Academic Press.