Their dark blue-green top and pure white underside distinguishes them. Males and females look quite alike.

They spend spring in all but the southernmost states and migrate to the Gulf coast and Mexico for winter. Migrating flocks may number in the thousands.

Tree Swallows take readily to nesting boxes placed out in the open in rural or suburban areas, and they are quite comfortable around people. Once you have them nesting on your property, you may find their population increasing if you put up more boxes each year, as they tend to return to the same spots each year, especially if insects are abundant. Tree swallows like to line their nests with grass and feathers. If you have access to chicken feathers or others, leave some around the nesting boxes, and the swallows will use them.

Prolonged periods of cold, rainy weather will inhibit the Tree Swallows' ability to catch insects, and the adults may travel a distance to find some. Unfortunately, this sometimes leaves the young too long without food, and they perish. But this will not keep them from returning to start a new nesting.

They lay 5 to 6 pure white eggs and generally raise one brood each year, which is cared for by both parents. 

Tree Swallows feed on bayberries in the winter, allowing them to winter father north than other swallows. They are also among the first to migrate north in the spring.

Tree Swallows like playing with feathers, and can frequently be seen tossing one into the air and catching it, or chasing another swallow with a feather.

Tree Swallows will tolerate fairly close neighbors of their own kind. Nesting boxes may be placed as close as 30 feet apart, or even on the same tree. They should be mounted on posts or trees out in the open, near water. It is even acceptable to place the post in water.

Tree Swallows are good neighbors for Eastern Bluebirds and will even help to defend the less aggressive bluebird against its competitors. They like the same size nesting box, so placing two houses near each other, or even back-to-back on a post, will encourage Tree Swallows to occupy one and bluebirds the other. Otherwise, the more aggressive swallows will often use a bluebird house at the expense of the bluebirds.

Barn Swallows

The Barn Swallow (Hirundo rustica) is a relative similar to the Tree Swallow. Although not a strict cavity-nester, the Barn Swallow will nest on a nesting platform or perch making a cup-shaped nest with a mud foundation. This swallow can be distinguished from the Tree Swallow, as it swoops by gathering insects, by its steel blue back, rust colored breast and long forked tail.