This swallow's song is generally described as a soft trilling, with a rolled jeerrt call, and a sharp alarm note.

With an estimated population of at least 500,000 individuals, the mangrove swallow is classified as a species of least concern by the International Union for Conservation of Nature (IUCN).

The mangrove swallow was formally described in 1863 as Petrochelidon albilinea by American amateur ornithologist George Newbold Lawrence.

[3] The genus name Tachycineta is from Ancient Greek takhukinetos, "moving quickly", and the specific albilinea is from Latin albus, "white", and linea, "line".

DNA sequence studies suggest that there are three major groupings within the Hirundininae, broadly correlating with the type of nest built.

[7] It is also differentiated from the mangrove swallow by its lack of a supraloral white line and by its slight difference in size.

The adult has iridescent blue-green upperparts, white underparts, rump, and undertail- and wing-coverts, and blackish tail and flight feathers.

The iris is a dark brown, and the tarsus and toes range in colour from black to fuscous-brown.

[8] This swallow is native to Mexico and all of Central America (Belize, Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica and Panama).

It is usually found near low-lying bodies of water and mangrove forests, which gave rise to the common name.

[8][10] The mangrove swallow is closely associated with fairly still, open water, and is often found in small flocks over rivers or lakes when not breeding.

[12] The nest is a few centimetres deep and made with grass, fine stems, moss, and a few leaves and sticks.

Extra-pair young are also correlated with the breeding synchrony index, or the percentage of females fertile simultaneously.

The fact that the laying of eggs is not synchronized within a population is due to the long breeding season of the mangrove swallow.

[14] The mangrove swallow subsists primarily on a diet of small, flying insects, including large species such as dragonflies and bees.

This swallow usually feeds close over bays, lakes, and large rivers, but sometimes can be found to forage 30 metres (98 ft) or more above the water.

Non-breeding mangrove swallows normally forage in small flocks, although when breeding, it feeds alone or in pairs.

[9] The mangrove swallow typically stays within about 100 metres (330 ft) of its nest when it is foraging for the nestlings.

[7] Not much is known about the predators and parasites of the mangrove swallow, although it has been known to lose nests to termites and black flies.