A study conducted at Cornell University demonstrated that females are more efficient hunters, because they can catch larger prey species, and therefore need to make fewer hunting expeditions, and as a result conserves energy. However, during incubation and while the chicks are young, the female spends most of her time at the nest, and does little hunting. The male therefore ends up providing most of the food during this time. The result of this is that when the chicks are young, they are fed small birds such as sparrows and starlings, whereas when they are older and need more food, the female begins to hunt again and brings larger prey such as pigeons and ducks. Peregrines, as well as many other predatory species, can eat large quantities of food in one sitting, which is to their advantage because they never know when they will get their next meal.
Peregrines can, in one sitting, eat a meal weighing as much as one quarter of their own weight.
Additional food is usually stored in caches to be returned to at a later time when fresh food is scarce. In years when voles and lemmings are abundant in the Arctic, Tundra Peregrines will often feed primarily on them, rather than on other birds. Dozens of species of birds have been recorded as prey, ranging in size from chickadees and goldfinches to pigeons, ducks, and gulls. While on migration, many Peregrines hunt primarily shorebirds. In natural areas, Peregrines often nest near wetlands.