Eastern Whip-poor-will

This medium-sized nightjar measures 22–27 cm (8+1⁄2–10+1⁄2 in) in length, spans 45–50 cm (17+1⁄2–19+1⁄2 in) across the wings and weighs 42–69 g (1+1⁄2–2+7⁄16 oz). Further standard measurements are a wing chord of 14.7 to 16.9 cm (5+13⁄16 to 6+5⁄8 in), a tail of 10.5 to 12.8 cm (4+1⁄8 to 5+1⁄16 in), a bill of 1 to 1.4 cm (3⁄8 to 9⁄16 in) and a tarsus of 1.5 to 1.8 cm (9⁄16 to 11⁄16 in). Adults have mottled plumage: the upperparts are grey, black and brown; the lower parts are grey and black. They have a very short bill and a black throat. Males have a white patch below the throat and white tips on the outer tail feathers; in the female, these parts are light brown. This bird is sometimes confused with the related chuck-will's-widow (Antrostomus carolinensis) which has a similar but lower-pitched and slower call.

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. Eastern whip-poor-will are typically socially monogamous. However, a male whip-poor-will was once recorded attending the nests of two different females, possibly because one female's previous mate had recently died. 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.