Sub-category: Swallows & Martins
The bill is tiny. The adult tree swallow has iridescent blue-green upperparts, white underparts, and a very slightly forked tail. The female usually has duller colours than the male, often more greenish than the more bluish male. The juvenile plumage is dull grey-brown above and may have hint of a grey breast band.
Being highly social outside of the breeding season, tree swallows may form flocks of several thousand birds near roost sites. Tree Swallows nest in natural or artificial cavities near water and are often found in large flocks. They readily use nest boxes, including those built for bluebirds. They subsist primarily on a diet of insects, sometimes supplemented with small quantities of fruit. They are excellent fliers and take off from their perch and acrobatically catch insects in their bills in mid-air.