It says the swallow is mainly an insect-eating bird. Different species of swallows prefer different types of insects. For example, the Purple martin typically eats dragonflies, moths, and butterflies. Barn swallows consume large flies, and when the weather is bad they eat other insects off the ground. Besides insects, the Tree swallow eats a variety of seeds and berries.
Bayberries are a favorite of the tree swallow.
Amazingly, swallows come back to the same nests year after year. It says young swallows usually build their nests within just a few miles of the nest their parents inhabit. Swallows repair old or weakened nests which last for many years. An average swallow lives about four years, and old nests in good condition are often taken over by new tenants. Swallows usually stay with the same mate for life.