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Common Name: Common Nighthawk
Scientific Name: Chordeiles minor

(Information for this species page was collected in part by Mr. Joseph Maltese for Biology 220W at Penn State New Kensington in Spring 2013)

Common nighthawk - Image credit: Gary Kramer, US Fish and Wildlife Service Digital LibraryThe common nighthawk (Chordeiles minor) is a slim bodied, medium-sized bird (nine inches long), with long, slender, pointed wings (a twenty-two inch wingspan). Its feathers are a mottled swirl of brown, tan, white, and gray that so well camouflage the bird on the ground that it seems to just disappear when it lands and settles. It has a tiny beak but a very large, gaping mouth that it holds wide-open to gather insect prey in flight. Its wing shape enables it to fly very rapidly and also enables it to make very sudden and extremely agile maneuvers in flight in order to efficiently gather up great numbers of its insect prey. Image: Gary Kramer, US Fish and Wildlife Service Digital Library.

The common nighthawk is a solitary bird with rigidly defined and aggressively defended territories. In urban areas these territories average twenty-five acres in size, while in rural areas they can be nearly seventy acres. Prime characteristics of a territory include suitable nesting habitats (flat roofs in urban zones, and forest clearings, grasslands, sand dunes, rocky outcrops or cliffs, or farm fields in rural zones), small and large trees (for sentry perches and resting roosts), abundant insect prey, and a water source. Combinations of these habitat features can be found all across North America and the ability of the common nighthawk to adapt to variations in these variables explains the transcontinental distribution of this species.

Migration, Mating and Reproduction
The common nighthawk overwinters in South America as far south as Argentina. It migrates these many thousands of miles in large flocks via long, sustained flights that are broken up by several days of resting and feeding in suitable habitats along the way. Warm temperatures and the availability of large numbers of flying insects seem to be the main drivers of the nighthawk’s migration. Females arrive at their northern breeding sites in late May or early June. The females select a suitable nesting site (individuals often return to the same site for many years in a row) and wait for the arrival of the males. When the males return they fly about making their high pitched “peenting” calls for the waiting females. The males also carry out wildly energetic flight displays to catch the attention of a female. These in-flight displays may then be accompanied by “booming” dives over the female’s nest spot and on the ground wing displays (especially showing off the bright white throat patches of the male).

Mating occurs on the ground and the fertilized female will eventually lay two eggs usually one or two days apart on her selected spot. There is no real nest, though. The coloration of the eggs (cream colored to pale greenish gray with dark brown blotches) makes them extremely hard to see and the aforementioned incredibly effective camouflaging of the adult birds make the nest spot very hard to locate. The female incubates the eggs for eighteen to twenty days, and then both the male and the female vigorously feed the nestlings for eighteen more days until the young fledge. The young nighthawks are weaned when they are twenty-five days old. If a second clutch is attempted the male assumes all of the responsibility for the nestling feeding while the female incubates the second batch of eggs.

Predators
Ground nesters are subject to many potential nest predators (including skunks, foxes, snakes, ravens, and crows). Urban nesting nighthawks also have to contend with domesticated dogs and cats. To reduce this predation, female nighthawks frequently move the exact location of their nesting site. The nestlings follow the female to a new site thus reducing the overall scent markings of their location. Males perch in sentry trees near the nest to react to intruders and potential predators. The males will swoop down on the intruder and even make loud, “booming” sounds (caused by wind rushing across his wing tips). The females will also defend the nest site especially by feigned injury behaviors that draw the intruder away from the nestlings. The nestlings also act to protect themselves by puffing up their feathers and hissing loudly at any foreign visitor.

The common nighthawk stays in its breeding areas until cold weather or a decline in insect numbers is perceived. This typically occurs in the early weeks of September. They then form very large migratory flocks that find their way to the insect rich habitats across most of northern and central South America.
Common nighthawks are most active in the hour or so around dawn and around dusk. They need to use their vision to locate their insect prey, so they cannot really hunt in the very dark hours of the night. During the day they stay primarily in their ground nesting areas relying on their excellent camouflage to protect them from harm. Common nighthawks sometimes relax their rigid territorial restrictions when an extremely abundant mass of insects comes available. In urban areas this often occurs around the lights of parking lots and sporting venues. The large flocks of light-attracted insects will draw a number of common nighthawks together to feed in their marvelously, acrobatic ways!

There is a general decline in common nighthawks all across North America especially in urban areas. The lack of suitable nesting sites is thought to be the primary reason for this decline.


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