Tree swallow

Tree swallow
In Madison, Wisconsin, US
Conservation status
Least Concern (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Passeriformes
Family:	Hirundinidae
Genus:	Tachycineta
Species:	T. bicolor
Binomial name
Tachycineta bicolor (Vieillot, 1808)
Range of T. bicolor       Breeding summer visitor     Migration visitor      Winter visitor
Synonyms
Iridoprocne bicolor

Flying in Central New York, US

The tree swallow (Tachycineta bicolor) is a migratory passerine bird that breeds in North America and winters in Mexico, Central America and the Caribbean. It is a very rare vagrant to western Europe.

This swallow averages 13.5 cm (5.3 in) long and weighs about 20 g (0.71 oz). 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. Flocks near Vacherie, Louisiana, were estimated to contain well over 1 million birds during December 2009.

Breeding

Mating

Nesting

Egg, Collection Museum Wiesbaden

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. Declines in cavity-builder populations are resulting in fewer natural nesting sites for tree swallows, although the swallow population remains healthy.

The tree swallow nest consists of multiple layers of grasses and thin twigs, and is often lined with feathers from other species. The female lays four to seven white eggs and incubates them by herself. The eggs hatch in about 14 days and the hatchlings are altricial. The hatchlings typically fledge in 16–24 days. While there are young or eggs in the nest, adults frequently dive bomb intruders (including curious humans) and attempt to drive them from the area. Tree swallows are known to "fight" over feathers in mid-air for reasons which are still under investigation. There is some speculation that this is a form of play.

Tree swallows are typically single-brooded, although they may attempt a second nest if the first fails early in the season. There are records of parents raising two successful broods in a season.

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.

External links

• Tree swallow - Tachycineta bicolor - USGS Patuxent Bird Identification InfoCenter
• Tree swallow species account – Cornell Lab of Ornithology
• How to create and manage nest box projects for tree swallows
• Tree swallow videos, photos, and sounds at the Internet Bird Collection
• Tree swallow photo gallery at VIREO (Drexel University)
• Tree swallow, borealforest.org