The Tree Swallow winters farther north than any other North American swallow, and returns to the nesting grounds weeks before the other swallows return in the spring. This is a cavity-nesting swallow and usually nests in old woodpecker holes, but readily accepts nest boxes. The Tree Swallow only started nesting in Tennessee in 1968, and the reason for this range expansion is not clear. The breeding range is very large extending from Alaska across much of the United States. The winter range extends across the southern edges of the United States, southward into Mexico.
Description: The Tree Swallow is glossy greenish-blue above and white below, with long, broad, pointed wings. The face is dark, the throat and cheeks are white, and the tail is notched. Adult males and females look similar, but females in their first year may be brown on the back with varying amounts of greenish-blue on the crown and back. Juveniles (May-September) are sooty gray on the back, dull white below, with a faint grayish band across the chest.
Weight: 0.7 oz
Habitat: Open areas near large or small bodies of water, especially wooded swamps.
Diet: Primarily flying insects, but also some fruit in winter.
Nesting and reproduction: In Tennessee, nesting begins in April, when migrating swallows are still present, and peak egg laying is in mid-May. Nest Box Instructions here.
Clutch Size: 4 to 6 eggs, with 5 most common.
Incubation: The female incubates the eggs for 13 to 16 days.
Fledging: The male and female feed the young, which fledge when about 20 days old. The adults and young may leave the nesting area soon thereafter, and join large flocks in early July.
Nest: The open cup nest is built by the female, and made of grass or pine needles, and lined with bird feathers. It is placed in the cavity of a tree or in a nest box.
Status in Tennessee: The Tree Swallow is an uncommon summer resident across the state, present from mid-March until mid-October. It can be locally abundant during spring and fall migration, especially near the Mississippi River. This species only started nesting in Tennessee in 1968, and is continuing to expand its nesting distribution.
Dynamic map of Tree Swallow eBird observations in Tennessee
- The first nest record for the Tree Swallow in Tennessee was in 1918 at Reelfoot Lake, but there were no additional nest records until 1968 when nests were found in Anderson and Maury Counties. Tree Swallows are now found nesting in scattered locations across the state. The reason for their rapid expansion into Tennessee, and elsewhere in the range, is not known.
- Tree Swallows are unlike other songbirds in two ways, 1) the female requires 2 years to attain adult plumage, even though she is fully capable of successfully breeding in her first year, and 2) most birds do not return to breed in the area where they hatched.
- During the non-breeding season, Tree Swallows congregate in enormous flocks, often in the hundreds of thousands, near roost sites.
- Tree Swallows are famous for using feathers from other birds to line their nest. These feathers not only keep the nestlings warm, but also appear to reduce the numbers of ectoparasites affecting the young.
- The oldest known Tree Swallow in the wild was 12 years 1 month old.
Best places to see in Tennessee: Found across the state near large and small bodies of water, especially wooded swamps.
For more information:
Tennessee's Woodworking for Wildlife page with nest box instructions
How To Create And Manage Tree Swallow Nest Box Projects
Nicholson, C. P. 1997. Atlas of Breeding Birds of Tennessee. Univ. of Tennessee Press, Knoxville.
Robertson, R. J., B. J. Stutchbury and R. R. Cohen. 1992. Tree Swallow (Tachycineta bicolor), The Birds of North America (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, PA, and The American Ornithologists' Union, Washington, D.C.
Robinson J. C. 1990. An Annotated Checklist of the Birds of Tennessee. Univ. of Tennessee Press, Knoxville.
Sibley, D. A. 2000. The Sibley Guide to Birds. A. A. Knopf, New York, NY.