Tree Swallows (Tachycineta bicolor) are one of our earliest arrivals in spring on Cape Cod. They prefer open areas near water and use cavities in trees for nesting. They are attracted to nest boxes placed in marshes or fields.  Feathers from other birds are gathered to make their nest. Their feeding preferences include insects, which they gather while in flight, but they also enjoy seeds and berries.  Outside of the breeding season they gather in large flocks especially during fall migration.