The eastern whip-poor-will (Antrostomus vociferus) is a medium-sized (22–27 cm) nightjar from North America. The whip-poor-will is commonly heard within its range, but less often seen because of its superior camouflage. It is named onomatopoeically after its song.
Eastern whip-poor-wills breed in deciduous or mixed woods across central and southeastern Canada and the eastern United States, and migrate to the southeastern United States and to eastern Mexico and Central America for the winter. These birds forage at night, catching insects in flight, and normally sleep during the day. Eastern whip-poor-wills nest on the ground, in shaded locations among dead leaves, and usually lay two eggs at a time. The bird will commonly remain on the nest unless almost stepped upon.
The eastern whip-poor-will is becoming locally rare. Several reasons for the decline are proposed, such as habitat destruction, predation by feral cats and dogs, and poisoning by insecticides, but the actual causes remain elusive. Even with local populations endangered, the species as a whole is not considered globally threatened due to its large range.
The whip-poor-will has been split into two species. Eastern populations are now referred to as the eastern whip-poor-will. The disjunct population in southwestern United States and Mexico is now referred to as the Mexican whip-poor-will, Antrostomus arizonae. The two populations were split based on range, different vocalizations, different egg coloration, and DNA sequencing showing differentiation.