24 March 2021
Breed in fields, marshes, shorelines, wooded swamps, and beaver ponds throughout northern North America, preferring to live near bodies of water that produce multitudes of flying insects for food. For nesting they need old trees with existing cavities (typically made by a woodpecker), or human-made nest boxes. Migrating and wintering birds use habitats similar to their breeding habitat, except they may have no need for cavities and are free to live in open areas.
Tree Swallows live on a diet of insects, though they occasionally capture other small animals and may eat plant foods during bad weather when prey is scarce. They feed from dawn to dusk in sheltered areas full of flying insects, usually foraging no more than 40 feet from the ground. Tree Swallows eat all kinds of flying insects: dragonflies, damselflies, flies, mayflies, caddisflies, true bugs, sawflies, bees, ants, wasps, beetles, stoneflies, butterflies, and moths, as well as spiders, mollusks, and roundworms. Their prey may be smaller than a grain of sand or up to two inches long. They chase prey in the air, with acrobatic twists and turns, and sometimes converge in large numbers in an insect swarm. During the breeding season, Tree Swallows eat high-calcium items like fish bones, crayfish exoskeletons, clamshells, and eggshells of gulls or loons.