Simulation models of the interactions between herbivore foraging strategies, social behavior, and plant community dynamics

Herbivory often operates through a feedback in which herbivores affect the success and location of plants, which in turn affects the foraging behavior of animals. Factors other than food, such as social behavior, may influenc e the interactions between herbivores and the plants they consume. We used a simulation model to compare the effects of foraging and social behavior o n plant distribution and foraging efficiency by gophers (Thomomys bottae) i n a system characteristic of California grasslands. In this system, annual forbs are the preferred food items, and their abundance increases in areas disturbed by gopher burrowing. In addition, gopher social interactions gene rate buffer zones between adjacent burrows. During the first year of the si mulations, before gophers affected the plant community, feeding efficiency declined with increased gopher density. However, after 40 yr, annual plant abundance increased with increasing gopher density, yielding higher maximum gopher density and per capita foraging efficiency. Conversely, increased w idth of the buffer zones lowered maximum gopher density and annual plant ab undance resulting in lower feeding efficiency. In addition, the compact bur row structure of gophers employing an area-restricted search strategy allow ed a higher density of gophers to coexist, resulting in higher annual plant abundance and higher per capita food-capture rates.