The diet of the grey fox is almost as diverse as that of the red´s. Fully omnivorous, the grey fox´s vegetarian diet includes fruit, grasses, grains, and nuts. Small mammals such as mice and rabbits are typical prey. Because of its arboreal nature, the grey fox also feeds on squirrels and birds much more frequently than other species. Insects provide an additional food source, and can make up a substantial portion of the diet when plentiful.