Nightjars and nighthawks | Caprimulgidae

Nachtzwaluwen | Chotacabras

In the dark, these birds give themselves away through a bright, orange-red eyeshine: a reflective layer behind the retina, the tapetum lucidum, boosts the little available light and makes them easy to find with a flashlight. The nightjar itself gives the family its English name with a rasping song that can continue for hours after dark from a fixed singing post, while other family members clap their wings during display or dive steeply with a booming sound produced by their tail feathers. Some species also display in flight by day, giving a sharp, nasal call that carries far across open ground. One northern member of the family, Phalaenoptilus nuttallii, is the only bird known to drop into a true state of torpor for weeks at a time when food runs short, with body temperature and heart rate sharply reduced.