The tree swallow, scientifically known as Tachycineta bicolor, is a migratory bird that belongs to the Hirundinidae family. Native to the Americas, this avian species was initially identified and named Hirundo bicolor by the renowned French ornithologist Louis Vieillot in 1807. However, it has subsequently been reclassified under its present genus, Tachycineta, although there are ongoing discussions regarding its precise phylogenetic position within this group. Distinguished by its vibrant blue-green plumage on the upper body, the tree swallow’s wings and tail possess a darker blackish shade, while its underparts appear white in coloration.
The tree swallow is a small bird, measuring around 12 to 14 cm in length and weighing approximately 17 to 25.5 g. It has a wingspan of 30 to 35 cm. The male tree swallow has vibrant blue-green upperparts, with blackish wings and tail. Its underparts and cheek patch are white, while the underwing coverts are gray-brown. Its bill is black, eyes are dark brown, and legs and feet are pale brown. On the other hand, the female tree swallow is less colorful than the male, and sometimes has a brown forehead. The second-year female also exhibits brown upperparts, with a variable number of blue feathers. Some third-year females may also retain a portion of this subadult plumage.
Distribution and natural habitat:
The tree swallow is predominantly found in North America, where it breeds and resides. Its home spans an expansive region, reaching as far north as north-central Alaska and the tree line in Canada. In the eastern part of its range, it can be observed as southern as Tennessee, while in the west, it extends down to California and New Mexico. Positioned at the heart of its range is Kansas. On occasion, this species may even breed further south within the United States. Interestingly, stray tree swallows have been known to wander into areas such as the Arctic Circle, the northern Pacific, Greenland, and even parts of Europe.
The wintering range of the tree swallow extends from California and southwestern Arizona in the west to southeastern Virginia in the east. It then extends south along the Gulf Coast to the West Indies, Panama, and the northwestern South American coast. As it migrates, this species often makes use of stop-over sites where it stays for an average of 57 days during autumn. To reach its wintering range, the tree swallow typically follows one of three flyways: the Western flyway which lies west of the Rocky Mountains, the Central flyway which stretches from the Rocky Mountains to the Great Lakes and extends south into Eastern Mexico, and the Eastern flyway which spans from the Great Lakes eastward.
In terms of behavior, the tree swallow has been extensively studied and biologists, such as Jason Jones, have even proposed that it should be considered a model organism. While it can display aggression during the breeding season, outside of this period, the tree swallow is quite sociable and can form flocks that sometimes consist of thousands of birds.
Reproduction:
The tree swallow, being an adaptive bird, chooses to build its nests in pre-existing cavities, which can be either natural or man-made. Initially, these habitats were limited to forested areas, but the introduction of artificial nest boxes has significantly increased the bird’s ability to colonize open environments.
Interestingly, this particular swallow species exhibits a strong preference for nesting in the same location where it successfully bred the previous year. Only a small percentage of females (approximately 14%) and males (around 4%) venture out to find new breeding sites annually. In most cases, these brave explorers don’t travel far, usually settling in spots within a 10-kilometer (6.2-mile) radius from their original grounds.
Eating habits:
The tree swallow searches for food alone or in groups, flying up to 50 meters (160 ft) above the ground. Its flight is a combination of flapping and gliding. During the breeding season, it typically stays within a distance of 4 kilometers (2.5 mi) from its nest. However, when hunting for food for its hatchlings, it can venture as far as 200 meters (660 ft) away from the nest, always keeping it in sight. It usually feeds at a height of up to 12 meters (39 ft). The tree swallow’s diet consists of insects, which it catches in flight, but it also sometimes snatches insects from the ground, water, vegetation, and vertical surfaces.
A male tree swallow is perched on top of a birdhouse, basking in the warm rays of sunlight. Its feathers glisten and shine, adding to its charming appearance.
In terms of conservation status, the tree swallow is categorized as “least concern” by the International Union for Conservation of Nature. This classification is mainly attributed to its extensive habitat, spanning an impressive area of approximately 834,000 square kilometers. Additionally, the tree swallow boasts a stable population, estimated to be around 20 million individuals.
To further safeguard this species, the tree swallow is protected under the Migratory Bird Treaty Act in the United States and the Migratory Birds Convention Act in Canada.
Don’t miss the opportunity to witness the beauty of this male tree swallow in the accompanying video.
