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A medium-sized (5-6 inches) swallow, the Tree Swallow is most easily identified by its iridescent blue-green back and head, white breast, and notched tail. Adult Tree Swallows may be distinguished from adult Violet-green Swallows (Tachycineta thalassina) by that species’ greener back and white face; immature Tree Swallows, which are brown above and pale below, may be confused with other dark-backed New World swallows, such as the Northern Rough-winged Swallow (Stelgidopteryx serripennis) and Bank Swallow (Riparia riparia). Male and female Tree Swallows are similar to one another in all seasons. The Tree Swallow breeds across much of North America, occurring from Alaska and northern Canada south to the south-central United States. Gaps in this species’ breeding range occur where habitat is incompatible with breeding in portions of the interior west and on the Great Plains. During the winter, this species may be found from the southeastern U.S. and California south to Central America. Tree Swallows breed in a variety of open areas near water, particularly in areas where tree cavities (or, more recently, artificial nest boxes) are available for nesting. This species utilizes similar kinds of habitat in winter as it does during the summer, although nest site availability is not a concern at that time of the year. Although Tree Swallows mainly eat small flying insects, this species is unusual for a swallow in that it also eats berries, particularly those of wax myrtles (genus Myrica), during winter when insects are unavailable. In appropriate habitat, Tree Swallows may be observed flying over water or open country while catching insects in flight. During the breeding season, a stakeout at a tree cavity or nest box may reward the patient birdwatcher with views of adult Tree Swallows bringing food to young birds. This species is primarily active during the day.