Creatures of the night – Nighthawks and Poorwills

Nighthawks and Poorwills are a group of eight related species of birds that are cryptically colored for camouflage. They hunt insects by moonlight or in the twilight of dawn and dusk. In the nomenclature of The Sibley Guide to Birds, Poorwills are included in a larger group called Nightjars, all of which have large heads relative to body size.

 Nighthawk

The Common Nighthawk ( not really hawks) occurs all over the U.S. and southern Canada, but is apparently rare in southern Arizona.  Instead, we have the Lesser Nighthawk which is found in all Sonoran Desert habitats. The third Nighthawk occurs in the Antilles, in the West Indies. The Arizona-Sonora Desert Museum (ASDM) describes Nighthawks as follows:

“Nighthawks have large eyes, tiny bills, huge gapes, and short legs. They are 8-9 inches in size and are identified in flight by a white wing bar and pointed wings. Nighthawks are insect-eaters. The Nighthawk flies low, silently and gracefully, searching the sky for flying insects, and maneuvering quickly, almost like a bat. These birds are crepuscular, needing some light to hunt by. City lights may extend the activity of the more urban Nighthawk and also attract its prey. Lesser Nighthawks may also be seen until midmorning.”

See more information from the Cornell Lab of Ornithology including sound recordings here.

Common Poorwills, are one of five species of Nightjars.  They occur in the western U.S. and are related to the Whip-poor-will which is most abundant east of the Mississippi River.  However, the Sibley Guide to Birds shows that Whip-poor-wills also occur in southern Arizona and southern New Mexico.  ASDM decribes Poorwills as follows:

“Poorwills have large eyes, tiny bills, huge gapes, and short legs. They have rounded wings (7-8½ inches) and no white bar. Poorwills are insect-eaters. A hunting Poorwill sits on open ground, looking up into the sky for the backlit silhouettes of large moths or beetles. When it spots something, it flutters up, usually no higher than ten feet, and catches the insect in its mouth. These birds are crepuscular, needing some light to hunt by. Poorwills like hunting by moonlight (they’re lunarphilic) and on these nights they take over the niche of the lunar-phobic,  insect-eating bat. During the day, Poorwills rest on the ground or horizontally on a branch, well camouflaged by their cryptic coloration. During winter, Poorwills may migrate too. But they may also hibernate, greatly lowering body temperature, respiration, and heart rates for days, even months, at a time. This behavior is very unusual in birds — hummingbirds enter torpor, but only for one night. The first documented hibernating Poorwill was found in the Sonoran Desert, in a hollow in a rocky canyon. Its discoverer tried to find signs of life in this apparently dead bird by catching the condensation of its breath on a mirror, but failed. Ten days later, the bird still hadn’t moved, but when the man touched it, the bird winked at him.”

See more information from the Cornell Lab of Ornithology including sound recordings here.

ASDM calls Nightjars the “birds of mystery.”  They are well-camouflaged in shades of brown and gray, sleep usually on the ground during the day, and fly about at night seeking insects.

 

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