Like owls, nightjars are nocturnal, yet they differ in most other respects due to their diet, which in contrast to that of the predatory owls, consists of aerial insects caught on the wing. Generally small to medium-sized with long, slender, pointed wings and a long tail, their flight is buoyant and butterfly-like. The bill of nightjars is tiny, but it is surrounded by long (rectal) bristles and opens into an enormous mouth, features that enable them to snare and suck in moths and other insects in flight, the bristles also protecting the eyes from damage due to the impact of larger insects. Again, in contrast to owls, their perching posture is horizontal as their legs are very short and their feet feebly small. Indeed most species rest by day on the ground, where they rely on their exquisitely camouflaged plumage to hide from predators amongst the leaf litter. Their cryptic coloration is also useful when sitting on their eggs, which are laid directly on the ground rather than in a nest, and are themselves cryptically coloured to avoid detection by egg predators. So, too, are the downy chicks, which are capable of walking soon after they hatch.
Sally from the ground or perch, or ‘trawl’ back and forth with erratic, buoyant, slow flapping and short glides.