The white-tailed nightjar was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae.

[3][4] Based on a molecular phylogenetic study by Kin-Lan Han and collaborators published in 2010, the white-tailed nightjar is now placed with three other species in the genus Hydropsalis.

The tail appears slightly forked; all but the innermost pair of feathers are partially to completely white.

[10] The call is "a high, thin pt-cheeeeeeeee, the second note a long-drawn-out, rising whistle that falls slightly at end."

Calls include "a scratchy wheer in flight" and "a thin tic-tic" when flushed from a roost.

[10] It is found in the "ABC Islands", Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Guyana, Martinique, Panama, Suriname, Trinidad and Tobago and Venezuela.

The white-tailed nightjar is a bird of open landscapes such as savanna, pastures, scrubby grasslands, and hillsides with scattered bushes and thickets.

It mostly forages by sallying from the ground or perches but also will hunt in flight low over open grasslands.

No specific threats have been identified except on Martinique, where habitat destruction and introduced predators are cause for concern.