Chordeiles minor
common nighthawk

Common Nighthawks (Chordeiles minor) breed throughout much of North America and parts of Central America. Their winter distribution is less well known, but they are believed to range throughout middle South America in the lowlands east of the Andes. (; Poulin, et al., 1996)

Common nighthawks breeding habitats include coastal dunes and beaches, woodland clearings, grasslands, savannas, sagebrush plains, and open forests. They will also use habitat altered by human activity including logged or burned areas of forests, farm fields, and cities.

Common nighthawks choose nest sites on the ground in open areas with some cover from grasses, shrubs, logs, or boulders. They do not build nests. Instead, eggs are laid on a variety of substrates including sand, gravel, leaves, and bare rock. In areas of human habitation, common nighthawks often nest on flat, gravel roofs.

Little is known about the migration routes or winter habitat of common nighthawks. They have been seen migrating across wetlands, farmland, river valleys, open woodlands, and coastal dunes. They are presumed to prefer open country in their wintering sites and have been seen flying over cities and towns. (; Poulin, et al., 1996; Stiles and Skutch, 1989)

Common nighthawks are medium-sized birds. They are 22 to 24 cm long and weigh 65 to 98 g. Like other members of the Caprimulgidae, they have large mouths and eyes, and are cryptically colored. They have a notched tail and long, slender, pointed wings with white patches on the primaries. Males have a white tail band near the tip of the tail and a white throat patch. Females do not have a tail band and are more buff-colored on the throat. Both sexes have bold barring on the chest and belly, though light parts tend to be whiter on males and more buff-colored on females.

Nine subspecies of common nighthawks have been described. These are differentiated by light and dark color variations in the plumage. Common nighthawks are often confused with two very similar species of nighthawks: Lesser nighthawks (Chordeiles acutipennis) and Antillean nighthawks (Chordeiles gundlachii). Lesser nighthawks are slightly smaller than Common Nighthawks, with buffy undertail-coverts instead of white, and with the white wing-patch of the primaries slightly closer to the wing tip. They also forage closer to the ground than do common nighthawks. Antillean nighthawks are virtually indistinguishable from common nighthawks in the field but by call, a nasal killikidick with the same tone as common nighthawks’ peent. In the hand, Antillean nighthawks’ wing measurements are slightly shorter than common nighthawks’. (Ehrlich, 1988; ; Poulin, et al., 1996)

There is little information available about the mating system of common nighthawks. Males court females by displaying on the ground and in flight. They begin by flying 5 to 30 meters into the air and then diving steeply toward the ground, pulling up sharply about 2 meters above the ground. This display is accompanied by a “booming” noise made by the air rushing through the primary feathers of the male. Males then land near the female, spreading and shaking their tail from side to side, displaying their white throat patch, and making a croaking noise.

Common nighthawk breeding phenology varies throughout their range, with more southerly populations producing young as early as May and northerly populations as late as August. Little is known about pair formation or breeding activity. Female common nighthawks have been shown to arrive first at their breeding grounds and select the nest site. Banded individuals have returned to the same nest sites over multiple years. The age at first breeding is unknown for this species. Common nighthawks are assumed to breed once per year.

Females typically lay 2 eggs, 1 to 2 days apart. The eggs are pale, splotched with gray, brown, and black. The female incubates the eggs, leaving the nest in early evening to feed. Incubation periods vary throughout the breeding range between 18-20 days. After the young hatch, the female continues to leave the nest site to forage in the evening. She feeds regurgitated insects to the young before sunrise in the morning and after sunset in the evening. Nestlings are semiprecocial and able to move in response to the female’s calls within a day of hatching. The young can move to shade or sun to regulate their body temperature. After 16 days, young can hop. At 18 days they make their first flight, and can fly well at about 25-30 days old. By the time they are 30 days old, chicks have left the nest for good. Full development is achieved at 45-50 days, after which young may join migrating flocks. In southern parts of the breeding range, pairs may have a second brood. In this case, the male takes over feeding the young of the first clutch while the female incubates the second clutch. He will also feed the female. (; Poulin, et al., 1996)

The female of a breeding pair incubates the eggs and broods the young chicks. Though the young are able to move themselves only one day after hatching, the female may move them around to take advantage of nearby shade. The parents feed the chicks regurgitated insects until they are able to feed themselves at age 25 days or so. The male defends the nest site by wing-beating and hissing at intruders. The female may also defend the nest site by feigning injury or hissing at an intruder. (; Poulin, et al., 1996)

Common nighthawks are expected to live at least 4 to 5 years. The oldest known wild common nighthawk was 9 years old. (; Poulin, et al., 1996)

Common nighthawks are some of the last migratory birds to arrive at spring breeding grounds and some of the first to leave in fall. This is attributed to the fact that warm temperatures are requisite for flying insect activity in early evening and morning. Also, while some caprimulgids go into torpor to conserve energy on cold nights, common nighthawks are not known to do so, thus making them more sensitive to colder temperatures.

Common nighthawks migrate some 4,000 to 11,000 km (2,500 to 6,800 miles) – one of the longest migrations of any bird in the Americas. They migrate in flocks, especially in the fall, most passing through Middle America, but some crossing the Gulf of Mexico and Caribbean to Florida. They may be seen riding thermals at this time, much like migrating hawks.

Common nighthawks are highly territorial, solitary nesters. Males will defend their territory by diving at intruders. The territory size varies between habitat types, but appears to range between 41,000 and 280,000 square meters.

Common nighthawks are crepuscular. When not at the nest, Common nighthawks will roost, sleep, or sunbathe on fence posts, tree branches, the ground, or flat rooftops.

Bats and lesser nighthawks have been shown to displace common nighthawks from feeding sites by chasing them away. Lesser nighthawk aggression may exclude common nighthawks from mutually suitable habitats. (Elphick, 1995; ; Poulin, et al., 1996)

Common nighthawks use calls and displays to communicate with one another. The vocalizations of common nighthawks are very simple, and have few variations. They also use non-vocal sounds, such as the booming sound made by the primary feathers of males during a courtship display to communicate. An example of the physical displays used by common nighthawks is the diving display given by males to prospective mates. (; Poulin, et al., 1996)

Common nighthawks are crepuscular. They are most active at dawn and dusk, and rarely feed at night. They have been reported to occasionally feed during the day in low light conditions (stormy weather or fog, for example) They use their large mouths to “hawk” insects in the air. Their large eyes help them find and distinguish among prey items in the dark. Like owls, common nighthawks have a tapetum (a mirror-like structure at the back of each eye that reflects light to the retina) that increases their ability to see in the dark. They fly with erratic, bat-like movements, taking as many as 50 different insect prey species. Studies indicate that the majority of the diet is made up of queen ants (Hymenoptera), beetles (Coleoptera), and true bugs (Homoptera). It also includes moths (Lepidoptera), mayflies (Ephemeroptera), caddisflies (Trichoptera), flies (Diptera), wasps (Hymenoptera), crickets and grasshoppers (Orthoptera) and other insects. In the urban parts of their range, common nighthawks are often seen flying around streetlights or bright yard lights, catching insects that are attracted to the light.

Common Nighthawks drink while in flight by skimming the surface of lakes, streams, or water troughs with their bills. (Brigham and Barclay, 1995; Brigham, 1990; Nicol and Arnott, 1974; ; Poulin, et al., 1996; Terres, 1980)

Crows and ravens, owls, American kestrels, skunks, snakes, housecats and canids such as coyotes, foxes, and domestic dogs are predators of common nighthawks.

Females and young rely on their cryptic brown coloration to avoid detection of the nest site by predators. Males are not known to guard the nest but will defend it by diving over it and booming with their wings or beating the wings and hissing. Females may feign injury to distract predators from the nest. Chicks also spread their wings and hiss at intruders when threatened. (; Poulin, et al., 1996)

Common nighthawks help to control populations of the insects that they prey on. They also compete with bats and lesser nighthawks Chordeiles acutipennis for food. (; Poulin, et al., 1996)

Since common nighthawks are insect eaters that frequent farm fields and cities, it is likely that they help control pest insect species.

Common nighthawks have no known negative impact on humans.

Populations of common nighthawks are declining. This decrease may be attributed to a variety of human activities. Indiscriminate pesticide use in cities and farmlands affects populations locally. In urban areas, replacement of gravel roofs with rubber roofs has reduced nesting sites for these populations. Increased predation is also a factor in general population decline. Urban nesters are especially vulnerable to predation by housecats. Common nighthawks are also killed by vehicles when roosting or feeding along roadways. (Poulin, et al., 1996)

Personal anecdote:

Common Nighthawks are known for their loud, nasal “peent” calls made by both sexes, as well as the males’ amazing, booming courtship dives. My husband and I were equally freaked-out and captivated by their mysterious sounds one summer night in eastern Arizona. We were driving home from Colorado, and the sun had long-since gone down. Eyelids heavy, we pulled off onto national forest land just east of Show Low to camp for the night. We laid our tarp and sleeping bags on rough volcanic gravels in a sparse juniper woodland. There was no moon. Just as we had fallen asleep, we were awaken by a loud “peenting” noise, followed by a booming, zipping “woosh.” It passed right over our heads. A few seconds later, the peent came again from a completely different corner of the sky, followed by another close woosh above our heads. Our first thought was that bored teenagers from Show Low had somehow found our campsite and were messing with our minds. What WAS that sound?!? Strangely muffled gunshots? UFO’s landing? A huge bug-zapper? It just didn’t sound natural. How could something be in one spot, then abruptly be 200 meters away, making such a mechanized sound? Then, the sound ceased, leaving us to wonder its origins. We drifted off to sleep, only to be awoken a while before dawn.

Peent! Woosh! Silence. Peent… again from a spot impossibly distant from the first call…and woosh above our heads. Disbelief gave way to reason as we hunkered in our bags, commiserating: “It’s got to be a bird.” “Maybe some kind of nightjar?” Sure enough, as the sun gradually lightened the eastern sky, we began to make out an avian shape. It would flap up on slender, pointed wings, hover, give out a loud “peent”, and dive steeply. The mechanical woosh and zipping noise came with the dive and ceased with the bird’s abrupt return skyward. It would peent again a couple hundred meters from where it began its last dive, then plunge downward. Boom-woosh! As the sky lightened, we saw the flash of white wing-patches on a second bird – perhaps a female? Then they moved off and were gone. We consulted our bird books later and decided they must have been common nighthawks. Could they have been courting? Were we disturbing a nest site? We’ll never know. Though no records of nighttime diving displays exist for this species, we definitely witnessed them late into the night and well before dawn. An unforgettable experience!