Mechanisms of Habitat Selection by the Hispid Cotton Rat (Sigmodon hispidus)

Abstract

The Texas coastal prairie is composed of habitat patches characterized by monocots, dicots, or a mixture of both plant types. Radiotelemetry revealed that reproductive female hispid cotton rats (Sigmodon hispidus) preferred mixed habitats and avoided dicot habitats, whereas males did not show a preference. Such habitat selection can be attained by shorter distances moved or increased turning (i.e., area-restricted search). Reproductive females, but not males, moved shorter distances in mixed habitats. However, turns relative to straight-ahead movements for females, but not males, were fewer in mixed habitats than in monocot or dicot habitats suggesting directed foraging rather than area-restricted search. To obtain necessary amounts of nutrients, especially carbohydrates, protein, phosphorus, and calcium, reproductive females ingest both monocots and dicots. Directed movement may facilitate foraging for dicots because these food items occur in clumps in mixed habitats. Because their nutritional needs are less than those of females, males do not exhibit the same patterns of habitat selection. Differential patch occupancy was not explained by overhead plant cover, but more bare ground in dicot habitats may explain avoidance of these habitat types because of increased predation risk.