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.
Mating System: monogamous
Southern populations of common nighthawks may produce chicks as early as May, while northern populations may not produce young until August. Little is known about how breeding pairs form, or about their breeding activities. Female common nighthawks arrive first at the breeding grounds and choose the nest site. Some of return to the same nest sites every year. Common nighthawks probably breed once per year. We do not know how old they are when they first breed.
Females usually lay 2 eggs, 1 to 2 days apart. The eggs are pale, splotched with gray, brown, and black. The female incubates the eggs for 18 to 20 days, leaving the nest in early evening to feed. After the eggs hatch, the female continues to leave the nest to forage in the evening. She feeds regurgitated insects to the chicks before sunrise in the morning and after sunset in the evening. The nestlings are semiprecocial and can move themselves if called by the female when they are just a day old. The young can move themselves to shade or sun to regulate their body temperature. After 16 days, young can hop. At 18 days old, 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. They are fully grown 45-50 days after hatching, and probably join migrating flocks at that time.
In southern parts of the breeding range, breeding pairs may have a second brood. If this happens, the male feeds the young of the first clutch while the female incubates the second clutch. He will also feed the female.
Breeding season: spring and summer
Range eggs per season: 1 to 2.
Average eggs per season: 2.
Average time to hatching: 18-20 days.
Average fledging age: 18 days.
Average time to independence: 30 days.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)
Average time to hatching: 19 days.
Average eggs per season: 2.
The female of a breeding pair incubates the eggs and broods the young chicks. She may also move them around to put them into 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 beating his wings and hissing at intruders. The female may also defend the nest site by hissing or pretending to be injured.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Male, Female); pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female)