Nutrient Encounter by a Generalist Herbivore in a Heterogeneous Landscape

Abstract Most landscapes are heterogeneous in vegetation composition and thus, in the distribution of nutrients required by herbivores for growth and reproduction. Hispid cotton rats (Sigmodon hispdus) inhabit Texas coastal prairies which are characterized by habitat patches dominated by dicots, monocots or both [mixed] plant types. Hispid cotton rats must obtain nutrients necessary for reproduction by ingesting both dicots and monocots, and reproductive females concentrate their activity in mixed patches. Mixed patches may be selected because they have high nutrient contents or because presence of both monocot and dicot food plants lowers cost of foraging movements. Because hispid cotton rats select a nutritionally complete diet and may detect protein by odor and taste cues, we hypothesized that nutrient concentrations may cue position of foraging paths. We used nutrient maps to measure amount of protein, P and Ca encountered during foraging from radiotracked individuals. We compared these values to thos...