The Common nighthawk (Chordeiles minor) is a medium-sized crepuscular or nocturnal bird of the Americas. The presence and identity of these birds are best revealed by their vocalization. Typically dark, displaying cryptic coloration and intricate patterns, they are difficult to spot with the naked eye during the day. This bird is most conspicuous when in its buoyant and erratic flight.
This medium-sized bird has large, flattened head and long, narrow, pointed wings. The bill of Common nighthawks is small while the mouth and eyes are large. The long tail is notched and brown with buff bands. Across the long feathers, bordering the wings, the bird has wide white stripe, which is visible when flying. The throat band of female nighthawks is buff-colored whereas that of males is white. In addition, male nighthawks have a white stripe near the tip of the tail. Juveniles can be identified by the absence of buff-colored or white throat band.
The area of their distribution covers nearly all of North America, including all provinces and territories of Canada, except Nunavut. They also nest in some parts of Central America and, possibly, in southeastern Columbia. While migrating, these birds have been reported traveling through middle America, Florida, the West Indies, Cuba, the Caribbean, and Bermuda, finally completing their journey in the wintering grounds of South America, primarily Argentina. Common nighthawks occur mainly in open, vegetation-free terrains such as recently harvested forests, burnt-over and logged areas, lakeshores, river banks and beaches, dunes, rocky outcrops and rocky barrens, peat bogs, swamps, grasslands, prairies, savannas, and pastures. These birds can also be found in mixed and coniferous forests.
Common nighthawks are very territorial with males, fiercely defending their territory by diving at any intruders. The males of this species may roost together but these birds are primarily solitary. Common nighthawk hunts on the wing for extended periods at high altitudes or in open areas. Crepuscular, flying insects are its preferred food source. The hunt ends as dusk becomes night, and resumes when night becomes dawn. Nighttime feeding (in complete darkness) is rare, even on evenings with a full moon. The rest of the time they spend sleeping or roosting. In addition, they tend to sunbathe on tree branches, the ground, flat rooftops, or fence posts. With their horizontal stance and short legs, Common nighthawks do not travel frequently on the ground, instead preferring to perch horizontally, parallel to branches, on posts, on the ground, or on a roof. There are no differences between the calls and songs of the Common nighthawk. The most conspicuous vocalization is a nasal ‘peent’ or ‘beernt’ during flight. Peak vocalizations are reported 30 to 45 minutes after sunset. A croaking ‘auk auk auk’ is vocalized by males while in the presence of a female during courtship. Another courtship sound, thought to be made solely by the males, is the boom, created by air rushing through the primaries after a quick downward flex of the wings during a daytime dive. In defense of their nests, females make a rasping sound, and males clap their wings together. Common nighthawks migrate by day or night in loose flocks, frequently numbering in the thousands; flocks have not been observed with a visible leader. As aerial insectivores, the migrants will feed en route, congregating to hunt in marshes, rivers, and lakeshores. They travel huge distances, leaving for South America in September and wintering there. They return to their northernmost breeding grounds in Yukon Territory (North-western Canada) only at the beginning of June.
Common nighthawks are carnivores (insectivores). They feed mainly upon beetles, queen ants, mosquitoes, and true bugs. They can also consume insects such as grasshoppers, wasps, moths, flies, mayflies, caddis flies as well as crickets.
Common nighthawks are monogamous and form pairs. The breeding season lasts from mid-March to the beginning of October. The female usually lays 2 eggs at the interval of 1-2 days, incubating the eggs for 18-20 days. The chicks are semi-precocial, starting to respond to their mother's call within the first day of their lives. In the evenings, the female leaves the nesting site to forage. The hatchlings feed upon regurgitated insects. At the age of 16 days, they are able to hop while the first flight is at 18 days old. At 25-25 days old, the young can fly well, and by the age of 30 days, they leave the nest. The young are fully developed at 45-50 days old, joining flocks of migrating nighthawks.
The major threats to this species' population are alteration and loss of habitat. Another concern is the population decline of insect species due to the widespread use of insecticides, climatic fluctuations at breeding sites, and during migration and collisions with motor vehicles. Other threats include fire suppression, intensive agriculture with reforestation of abandoned agricultural fields and harvested forests, and reduction of flat rooftops, covered with gravel.
According to the IUCN Red List, the total population size of the Common nighthawk is 23,000,000 mature individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List but its numbers today are decreasing.
Common nighthawks control populations of prey species they feed upon. In addition, they compete for food with lesser nighthawks and bats.