Due to its rather secretive behaviour and cryptic colouration, the eastern whip-poor-will remains a relatively unstudied bird, with little known about its behaviour and ecology (2).
The eastern whip-poor-will forages at dusk and dawn and during moonlit periods at night. It typically makes short flights after insects from a perch in a tree or from the ground, and is also known to investigate rotten logs and leaves in search of food. The eastern whip-poor-will has a strictly insectivorous diet, consisting mainly of ants, beetles, flies, grasshoppers, moths and caterpillars (2).
At the start of the breeding season the male whip-poor-will is known to establish a fairly large territory, and from here produces loud, distinctive “whip-poor-will” calls from a variety of perches in an attempt to attract a suitable mate. The timing of breeding varies greatly with location, occurring sometime between late April and early July across most of its range (2).
The eastern whip-poor-will is a ground-nesting species, with the female laying a clutch of two eggs directly among leaf litter on the forest floor (2) (4). The newly laid eggs are cream or greyish-white, and are marbled and dotted with lavender-grey blotches and yellowish-brown or pale brown spots. This colouration fades fairly quickly and the eggs become well camouflaged to match the leaf litter, allowing them to remain undetected by most predators. The eggs are incubated mainly by the female, although sometimes by the male, for around 19 to 21 days, during which time the adult birds remain motionless on or close to the nest throughout much of the day (2).
Hatching of whip-poor-will chicks appears to be closely tied to the lunar cycle, with most young hatching a few days before a full moon. It is thought that this strategy may have developed to allow the adult birds to forage throughout the night during the full moon period, enabling them to catch enough insects to supply the chicks with sufficient energy to grow (2) (3). At around eight days after hatching, the whip-poor-will chicks develop black-speckled feathers to provide them with additional camouflage, after which they move from the nest site into denser cover (2). The male provides much of the care to the chicks after they leave the nest site until they are able to fly at around 20 days old, while the female often lays a second clutch of eggs nearby (2).