Bird diets

Bird diets may include only one source of food (monophagous) or many types of foods (polyphagous).

Invertebrates as prey
Birds feed on many types of animals including one-celled protozoans, hydras, jellyfishes, starfishes, sea urchins, sea anemones, marine worms; leeches, eath worms; crustaceans such as crabs, shrimps, crayfishes, sow bugs and barnacles; centipedes and millipedes; as well as arachnids (scorpions, ticks and spiders) and insects and most types of molluscs - slugs, squids, snails, mussels, oysters and limpets.

Vertebrates as prey
Vertebrate prey includes fish, salamanders, frogs, toads, turtles, lizards, and snakes and the small mammals such as shrews, bats, mice, rats, pocket gophers, ground and tree squirrels, rabbits and hares, and skunks.

The Golden Eagle may feed on porcupines, marmots, and even foxes and the young of deer and antelope are killed and eaten by it.

Some birds also prey on other birds - the predatory eagles, hawks, owls and shrikes capture and kill smaller birds, and crows, jays, magpies, skuas, jaegers, and gulls eat the eggs and young of other birds, and like the bald eagles and frigatebirds, rob other birds of their prey (kleptoparasitism).