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The Lesser Nighthawk, formerly known as the Texas or Trilling Nighthawk, is a little-studied, desert-dwelling bird of the American Southwest and Central and South America. Cryptically colored, it is mottled brown, buff, and black, with distinctive white crescents on its wing and throat. In North America it breeds in arid and semiarid habitat ranging from creosote/desert scrub to xerophilic low trees. During the day, individuals usually rest quietly on the open ground, where they blend in with the desert floor, but in the evening and early morning they can be seen flitting gracefully and buoyantly, low over the ground or skimming just above the tops of bushes, where they capture aerial insects in the scoop of their open mouth.
Lesser Nighthawks are apparently opportunistic feeders, taking whatever small flying insects are most abundant and easily captured. They do not actively patrol a well-defined territory, but roam over considerable distances in search of food and water, often foraging far from a nesting or roosting site. These birds often forage in pairs or family groups, but solitary individuals and large flocks are not uncommon at certain times of the year.
The species is known for its distinctive toad-like trill, given from a perch on the ground. Individuals court on the wing, and females lay their 2-egg clutch on the ground, without the benefit of a nest. Only the female incubates eggs, and she does most of the brooding of young. The male is the primary provider of food to the young, bringing them regurgitated insects.
Like other members of the family Caprimulgidae, Lesser Nighthawks have unusual physiological tolerances, especially in relation to heat and cold. In the summer, nesting individuals are exposed to extreme heat and often gular-flutter to enhance evaporative cooling. This behavior, combined with other behavioral traits, contributes to an unusually effective capacity for temperature regulation in hot environments. Although migratory, Lesser Nighthawks are capable of responding to cold weather and depressed food resources by remaining torpid for relatively long periods in a manner reminiscent of hibernating mammals.
Overall, this nighthawk appears stable in numbers, but habitat alteration and the use of insecticides may affect local populations. Much remains to be learned about the basic biology of this species.