Tree Swallow

The Tree Swallow (Tachycineta bicolor), a member of the family Hirundinidae, is a migratory bird that graces the Americas with its presence. It is a small bird, measuring between 12 and 14 cm in length and weighing between 17 and 25.5 grams. The male is resplendent with glossy blue-green upperparts, while the wings and tail are a contrasting blackish hue. The underparts are a striking white, and the bird possesses a black bill, dark brown eyes, and pale brown legs and feet. Females tend to be less vibrant than males, and juveniles can be identified by their brown upperparts and grey-brown-washed breasts.

Identification Tips

To identify the Tree Swallow, look for its glossy blue-green back and white underparts. The blackish wings and tail, along with the black bill, are key distinguishing features. Females may appear duller, and juveniles will have brown upperparts.

Habitat

Tree Swallows favor open and wooded areas, particularly those near bodies of water. They are adaptable birds that nest in both natural and artificial cavities.

Distribution

Breeding across the US and Canada, Tree Swallows winter from the southern US coasts down to Panama and the northwestern coast of South America, as well as in the West Indies.

Behaviour

Tree Swallows are known for their sociable nature outside of the breeding season, forming large flocks. They are also aggressive during breeding, defending their nesting territory with vigor.

Song & Calls

The Tree Swallow's vocal repertoire includes a song composed of chirps, whines, and gurgles, which may serve various functions from pair bonding to stimulating nestlings. Alarm calls are given in response to predators, and communication between parents and offspring can be disrupted by human-generated noise.

Breeding

Tree Swallows are socially monogamous, with some males exhibiting polygyny. They nest in cavities and lay clutches of two to eight pure white eggs, which are incubated by the female for about 14 to 15 days. Chicks generally fledge 18 to 22 days after hatching.

Similar Species

The Tree Swallow can be confused with other swallows, but its glossy blue-green upperparts and white underparts are distinctive.

Diet and Feeding

An aerial insectivore, the Tree Swallow forages both alone and in groups, consuming mostly insects, in addition to molluscs, spiders, and fruit. Both sexes feed the nestlings, which primarily eat insects.

Conservation status

The Tree Swallow is classified as Least Concern by the International Union for Conservation of Nature, with a stable population and a large range. It is protected under the Migratory Bird Treaty Act of 1918 in the US and the Migratory Birds Convention Act in Canada. However, human activities such as deforestation and lake acidification can negatively impact this species.