During the courtship process, the peregrines will typically engage in some type of food exchange as a way to strengthen the pair bond. Peregrine Falcons feed almost exclusively on birds, such as doves, waterfowl and songbirds, but occasionally they hunt small mammals, including bats, rats, voles and rabbits. Insects and reptiles make up a relatively small proportion of their diet. On the other hand, a growing number of city-dwelling Falcons find that feral pigeons and starlings provide plenty of food. Because of their high metabolic rates, Peregrine Falcons must consume more food in proportion to their size than most animals. To be efficient flyers, the digestive system of birds has to be both as light as possible and as efficient as possible.