- Though optimal foraging models usually consider only caloric needs of a model animal, other factors may influence foraging decisions. I manipulated predation risk using a lantern to alter illumination and looked for effects on rates of seed harvesting of a community of desert rodents. In all four replicates, increased illumination led to a decline in harvesting rate. This implies that increased predation risk decreased harvesting rates. In general, predation risk will influence foraging decisions and patch use.