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We investigated variation in perceived foraging costs to kangaroo rats (Dipodomys spp.) along a topographical gradient in the Chihuahuan desert. We used resources left in experimental seed trays to assess these costs. Both the proportion of trays in which Dipodomys foraged and the giving up densities of seeds in the trays decreased with elevation on hillside transects. These results suggest that kangaroo rat foraging activity was greater, with more trays encountered, at the bottom of the hills; however, microhabitat foraging costs (predation risks) were lower, yielding lower giving up densities of seeds in trays, at the tops of the hills. (C) 2001 Academic Press.