A common and widespread swallow from Canada to Panama, the tree swallow is an attractive species that is as hardy as it is beautiful. These birds often overwinter in southern parts of the United States, the northernmost winter range of any swallow species in North America.
- Bill: Small and stubby, black
- Size: 5.75 inches long with 12-13-inch wingspan, long pointed wings, slender build, slightly notched tail
- Colors: Blue, white, black, iridescent, brown
- Markings: Genders are similar with iridescent blue upperparts that may show a green tinge in bright sunlight. Wings and tail are black that may have a dark blue tinge. Underparts are plain bright white, including the chin and throat. In flight, a small white crescent may be visible on the sides of the rump. Eyes are black, and legs and feet are dark. Some females show a brownish hue to their plumage and lack the iridescent sheen. Juveniles have the same countershaded plumage that is dark dusky brown above and white below, and they may show a paler brown on the nape. Species is monotypic.
Insects, spiders, berries, seeds (See: Insectivorous)
Habitat and Migration:
These are adaptable swallows that can be found in a range of habitats. They prefer open areas near a reliable water source, such as open riparian corridors, wooded swamps or woodland edges, and they can also be found in urban or suburban areas. They have a relatively small year-round range in coastal southern California, but in summer the tree swallow's breeding range extends from Alaska through the boreal region of Canada and from the Pacific to the Atlantic coasts in the United States as far south as Utah, northern New Mexico, northern Arkansas and Tennessee. They are notably absent from the driest areas of the Canadian tundra and the Great Plains. In winter, the range of these neotropical migrants extends south through Mexico and Central America to Panama, and they can also be found on Cuba and other Caribbean islands.
Like many swallows, these birds are quieter than many passerines, but they do have a sweet song that intersperses musical chirps and whistles with a shallow pitch range. Typical calls are a faster, more frantic series of even chirps.
These are gregarious birds that gather in tremendous flocks after the breeding season and during migration and winter, and they may mix with other swallow species. They feed by catching insects in flight, but are rarely observed foraging on the ground as well. While they form loose colonies to breed, they can also be aggressive while defending their immediate nesting area. During migration, they are often the first swallow species to arrive on the breeding grounds in the spring and the last to leave in the fall.
These are polygamous birds and a male may take more than one mate during a breeding season, and he may select entirely different mate(s) in the next year. Courtship displays feature males performing aerial displays to impress females. These are cavity-nesting birds, and the nest is lined with shed feathers and down that the parent birds have collected from many other bird species.
One brood of eggs is laid per year, with 4-6 oval-shaped, white eggs. A second brood is very rare for tree swallows, but is possible in mild years or if the first nest is unsuccessful. The female parent incubates the eggs for 13-16 days, and after the eggs hatch, both parents care for the altricial young for an additional 15-25 days.
Attracting Tree Swallows:
Swallows can be difficult to attract to backyards, but tree swallows will readily nest in the same bird houses that are typically provided for bluebirds, and they may also try nesting in hollow gourds or gourd-shaped houses. Leaving dead or hollow trees intact for nesting sites and minimizing the use of pesticides will help encourage these birds to stay nearby, and they will also sample berry bushes in winter when insects are scarce.
These swallows are not threatened or endangered, and their population is considered abundant throughout much of their range. Overuse of insecticides and pesticides, however, can limit their numbers in urban or suburban areas, and the removal of dead trees can reduce the number of suitable nesting sites.