About Tree Swallows

Identification

• Male and female tree swallows are similar in size, with both sexes averaging between 4 1/2 inches and 6 inches long, according to the Cornell Lab of Ornithology. Tree swallows possess wingspans as large as 14 inches and weigh less than an ounce. Their forked tails are very noticeable when the bird is in flight. The female's color is a bit less vibrant than the male's is, with the juvenile featuring a grayish-brown back and head until they reach the age of 1 year.

Habitat

• Tree swallows make a point to avoid living in densely forested regions, where predators are abundant and it is more difficult to fly about catching insects. Tree swallows prefer habitats such as open wetlands, fields, marshes and the shores of rivers and lakes. The numbers of insects such as mosquitoes that comprise a large part of their diet are more plentiful and more easily captured in such settings. Tree swallows are what biologists term secondary-cavity nesters, notes the University of Maryland Extension. They utilize the abandoned holes in trees carved out by other birds and animals in which to raise their families.

Range

• Trees swallows live during the summer as far north as Alaska and throughout most of Canada, aided by their ability to eat such foods as bayberries. The tree swallow's range includes much of the West Coast, the Rockies, the Great Lakes region, New England and the northern states in the Deep South. The bird migrates in winter, motivated by a lack of insects to eat as the weather gets colder, heading to locales such as Florida, Mexico and Central America. The tree swallow comes back north earlier than any other type of North American swallow.

Behavior

• When tree swallows are not breeding, they usually form great flocks that can be in the hundreds of thousands in number. They can create what appears to be a dense cloud of birds as they circle at twilight, eating insects. Tree swallows employ feathers as part of their nesting material, lining nest boxes and hollows in trees with them to provide warmth for their chicks. The bird sometimes carries a feather and drops it, only to fly down and retrieve it before it touches the ground.