Owls are large-headed, short-necked birds of prey. Most are brown and gray. They have hooked claws and beaks for seizing and tearing animal prey. Large immobile eyes are set in feathered disks and look straight ahead. The whole head moves as the bird changes its gaze. Some have feather head tufts. Flight is silent. Best seen at dusk. Mobbing birds often reveal their location. Also look for regurgitated pellets of fur and bone below a nest or roost. The wings are large, broad, rounded and long. Like other birds of prey many owl species exhibit reverse sexual dimorphism in size, where females are larger than males (typically in birds males are larger).
Owls are generally nocturnal and spend much of the day roosting. They are often perceived as tame since they will allow people to approach quite closely before taking flight, but they are instead attempting to avoid detection. The cryptic plumage and inconspicuous locations adopted are an effort to avoid predators and mobbing by small birds.