the eastern whip-poor-will , caprimulgus vociferus , is a medium-sized (2227 cm) nightjar from north and central 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 .
this medium-sized nightjar measures 2227 cm (8.710.6 in) in length , spans 4550 cm (1820 in) across the wings and weighs 4269 g (1.52.4 oz) .
further standard measurements are a wing chord of 14.7 to 16.9 cm (5.8 to 6.7 in), a tail of 10.5 to 12.8 cm (4.1 to 5.0 in), a bill of 1 to 1.4 cm (0.39 to 0.55 in) and a tarsus of 1.5 to 1.8 cm (0.59 to 0.71 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 .
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 .
due to its haunting , ethereal song , the eastern whip-poor-will is the topic of numerous legends .
one new england legend says the whip-poor-will can sense a soul departing , and can capture it as it flees .
this is used as a plot device in h .
p .
lovecraft's story the dunwich horror .
this is likely related to an earlier native american and general american folk belief that the singing of the birds is a death omen .
this is also referred by whip-poor-will , a short story by james thurber , in which the constant nighttime singing of a whippoorwill results in maddening insomnia of the protagonist mr kinstrey who eventually loses his mind and kills everyone in his house , including himself .
the bird also features , however , in the runaway slave at pilgrim's point , a poem by the english poet elizabeth barrett browning , in which the outcast speaker asks: "could the whip-poor-will or the cat of the glen/look into my eyes and be bold?" it is also frequently used as an auditory symbol of rural america , as in washington irving's story the legend of sleepy hollow , or as a plot device .
for example , william faulkner's short story , "barn burning", makes several mentions of whippoorwills , e .
g .
: "and then he found that he had been asleep because he knew it was almost dawn , the night almost over .
he could tell that from the whippoorwills .
they were everywhere now among the dark trees below him , constant and inflectioned and ceaseless , so that , as the instant for giving over to the day birds drew nearer and nearer , there was no interval at all between them .
