Behavior And Reproduction
Most owls are active at night and sleep by day. Usually owls roost in sheltered spots—thick foliage or a branch close to a tree trunk. Some people think owls are "tame" because roosting owls may allow humans to come quite close. Actually, this behavior is an adaptation for avoiding detection by predators. If they're disturbed, owls pull their feathers in tight to look slim and lean close to the tree trunk to avoid being noticed. A few species are active by day, notably the snowy owl. This species lives in the Arctic, where daylight lasts twenty-four hours in the breeding season.
Because owls are active at night, they depend more on their ears than their eyes to communicate with other owls. Males mostly use vocalizations (sounds), rather than colorful feathers or flight displays, to get a female's attention. Owls also call to defend their territory and to stay in touch with each other. In most species, both sexes vocalize but the male calls more than the female.
Most owls are solitary. They hunt and roost alone, except during the breeding season. Most owls breed just once a year. They do not build their own nests. The smallest owls often nest in abandoned woodpecker holes. Larger owls use old crow or raptor nests, the top of a snag (a dead tree, standing, with the top broken off), a tree hole, a natural cave, or an abandoned building. A few species nest on the ground, including snowy owls and short-eared owls. Burrowing owls nest underground in prairie dog, badger, or ground squirrel burrows. Female owls do not gather any nest material. Eggs are laid on bare ground or the floor of the tree cavity.
A male and female owl bond by preening each other, straightening and cleaning their feathers. In many species, the male offers a gift of food to his mate. Owl eggs are white and more round than oval. A typical clutch ranges in size from two to four eggs for small owls to five to eight eggs for larger owls. In most species, the female lays one egg a day until the clutch is complete. But where many songbirds start to incubate the eggs after the clutch is complete, female owls start incubating with the first egg. That means the owlets hatch on different days and are of different sizes. Often, the youngest, smallest nestlings do not survive.