Aside from humans, the most common predators of birds are other birds and feral cats. Large birds with few or no natural predators, such as owls, hawks and eagles, sometimes eat smaller birds.
While birds of prey mostly eat rodents and small land-based animals, they may eat smaller birds if the opportunity presents itself. The amount of birds in their diet and the types eaten vary greatly, depending on species and environment. Different types of owls sometimes eat jays, crows, sparrows, starlings, ducks and pigeons. Different types of hawks also have varying amounts of small birds in their diet. The sharp-skinned hawk almost entirely subsists off of other birds, and the Cooper's hawk is estimated to eat small birds for at least half of its diet.
Cats are also common predators of birds, particularly feral cats without owners that roam at night and have been known to snatch birds from their nests. One feral cat can account for hundreds of bird deaths in a year. Dogs may eat ground-nesting birds if they encounter them. Birds may also be eaten by snakes, foxes, squirrels, weasels, opossums and raccoons.
While insects generally do not eat birds, the praying mantis may hunt and kill hummingbirds, and swarms of stinging insects may kill birds that are too close to their nests.