The ferruginous hawk primarily hunts small to medium-sized mammals but will also take birds, reptiles, and some insects. Mammals generally comprise 80–90% of the prey items or biomass in the diet with birds being the next most common mass component. The diet varies somewhat geographically, depending upon the distribution of prey species, but where the range of the ferruginous hawk overlaps, the black-tailed jackrabbit ("Lepus californicus") is a major food species along with ground squirrels and pocket gophers. Depending upon the relative abundance of jackrabbits and ground squirrels, the latter could become the major food source. Mammalian prey can range in size from tiny shrews and small bats to the black-tailed jackrabbit, weighing much more than a ferruginous hawk. Common prey items are: