© KURT LINDSAY
A FAMILY OF OWLS
Like hawks and eagles, owls are called raptors, or birds of prey, which means they use sharp talons and curved bills to hunt, kill, and eat other animals.
But owls are different from hawks and eagles in several ways. Most owls have huge heads, stocky bodies, soft feathers, short tails, and a reversible toe that can point either forward or backward. Owl’s eyes face forward, like humans do. Most owl species are active at night, not in the daytime.
There are about 250 species of owls in the world. They live on every continent except icy Antarctica.
Owls belong to a group of birds called Strigiformes. That group is divided into two smaller groups, known as families. The family called Tytonidae includes Barn Owls, which have heart-shaped faces. The second family, Strigidae, includes all other owls, most of which have round faces.
Many owls vocalize at a distinctively low frequency, which allows their songs to travel long distances without being absorbed by vegetation. Becoming familiar with these songs and other vocalizations will help you find and identify owls.
© DANIEL J COX / NATURALEXPOSURES.COM
© KURT LINDSAY
OWLS ON THE HUNT
Many owl species are nocturnal, meaning they are active at night. There are some owl species who are diurnal, however, meaning they are active during the day but rest at night. Crepuscular species are active during dusk and dawn.
Owls spend much of their waking time hunting for food. Many owl species are carnivores, or meat eaters. Small, rodent-like mammals, such as voles and mice, are the primary prey for many owl species. An owl's diet may also include frogs, lizards, snakes, fish, mice, rabbits, birds, squirrels, and other creatures. Occasionally, Great Horned Owls might even find skunks tasty enough to eat. Some owls, like the Flammulated Owl eat insects almost exclusively. Animals that eat insects are called insectivores.
Owls hunt in various ways. One hunting technique is called perch and pounce. In this method owls perch comfortably until they see their prey, then glide down upon it; Northern Hawk Owls use this approach. Another approach to hunting, called quartering flight, is to search for prey while flying, as utilized by the Barn Owl.
Sometimes owls – most often those that hunt in open country like the Short-eared Owl – hover like a helicopter above prey until they are ready to zoom in on it. Hovering takes a lot of energy. Burrowing Owls commonly run across the ground after their prey. In all methods, owls generally hunt close to the ground so that they can more easily hear and see their prey.
Owls sometimes hide their food. They capture prey and use their bill to carefully stuff the food into a hiding spot. This is called caching (pronounced CASH-ing). Owls might cache prey in holes in trees, in the forks of tree branches, behind rocks, or in clumps of grass. Owls do this when the hunting is good in order to stock up and will usually go back for the prey within a day or two.
HANGING OUT - ROOSTING
At the end of a day or night spent hunting, owls return to a resting place, called a roost. Most owls roost alone, or near a nest during the breeding season. However, there are a few species that roost communally, or share a roosting area with other individuals of the same species.
Although poorly understood, owls may benefit in one or more ways from sharing the same roost. The owls can watch for mobbing songbirds and predators. They may also huddle together to keep each other warm. Shared roosts probably make it easier for owls to find partners during the mating season. Owls may even pass along information about good hunting spots. The roost is commonly located next to good hunting grounds so owls can search for prey as soon as they leave or return to the roost.
© KURT LINDSAY
PAIRING UP - MATING SEASON
Late winter is mating time for most owls. Males begin seeking mates by calling through the afternoon and evening air.
Generally, the large owls hoot and the small owls toot. The large Barred Owl hoots in a loud, low call that sounds like a question, "Who cooks for you? Who cooks for you all?" The small Northern Saw-whet Owl sings in a rapid, high tone that some people think sounds like a file being scraped across the teeth of a saw. You can listen to the individual owl calls on our Owl ID pages.
A female owl will listen for a call that interests her. She will only respond to calls from males of the same species. Once a male owl gains the interest of a female, he starts performing, or showing off. He might display his feathers by fluffing them out. He might give the female gifts of food. Some males even ‘sky dance.’ A male Short-eared Owl will circle high above the female he is courting and clap his wings under his belly several times during a dive. Then he will fly up again and hang in the wind. He may repeat this dance several times, all in an effort to impress the female. At the end of the performance, the male dives past the female into the grass. If the female follows him, the two owls may become a mating pair.
Mating owls spend a great deal of time together. They may rub their bills across each other’s heads and facial discs. This gesture is called preening. Scientists think it reduces fighting and other aggressive behavior. It also helps owls keep their feathers in good condition. Many owl pairs stretch their necks forward toward their mates and coo, as if they enjoy the preening session.
© KURT LINDSAY
HAND-ME-DOWN HOMES - NESTING
Owls are talented hunters, but nest builders they are not. Many owls take advantage of the hard work performed by other animals, instead of building their nests from scratch.
Some owls, like Great Horned Owls, use vacant nests in trees or on cliffs that were built by hawks, crows, magpies, or other birds. Many owls simply nest in holes, called cavities or hollows, in trees. These tree cavities occur naturally, but are often created by woodpeckers. Elf Owls nest in saguaro cacti, where woodpeckers have created ready-made holes.
Barn Owls typically nest in the rafters of barns, in empty buildings or silos, or in cavities along cliffs. Burrowing Owls live up to their name by nesting in underground tunnels that were dug by ground squirrels, prairie dogs, badgers, or other burrowing animals. Some Burrowing Owls use their feet and bills to dig burrows themselves. Snowy Owls and Short-eared Owls "build" simple nests by scraping a shallow bowl on the ground.
Scientists think male owls find and advertise a territory, but female owls select the actual nest sites. Together, the owl pair defends their nest. The nest area will be the owl family’s home for several months.
© DANIEL J COX / NATURALEXPOSURES.COM
RAISING A FAMILY - INCUBATION
If local food supplies are low in a given year, owls may not breed there. But if enough food is available to feed a growing family, female owls lay one to fourteen roundish white eggs. Females from different owl species lay different numbers of eggs. The number also depends on how much food is available. For example, if local vole populations are high, a female Short-eared Owl might lay as many as ten eggs. If the vole population is low, she might lay just three or four eggs, or none at all.
Eggs are usually laid one to four days apart. The female owl sits on the eggs to keep them warm. This is called incubation. Only female owls incubate eggs. During the incubation period, the female loses the feathers on her belly in order to transfer more body heat to the eggs. She presses the warm bare skin, or brood patch, against the eggs. She lies on the nest in the incubation position, with her head low and stomach down, keeping the eggs warm all the time.
Baby owls, called owlets or nestlings, hatch 3 to 5 weeks after the eggs are laid, depending on the species. Because eggs are laid on different days, the female will generally begin incubation with the first egg, and the eggs will hatch in the order they were laid. This is called asynchronous hatching, which results in different age nestlings within the same nest. The first nestlings to hatch can be one to two weeks older than the last ones to hatch.
© DANIEL J COX / NATURALEXPOSURES.COM
RAISING A FAMILY - BROODING
When young owls hatch, they are covered with white, downy feathers and their eyes are closed. Several days after hatching, their eyes open and their white downy feathers are replaced with darker ones, often gray or brownish. When the female sits on a nest of hatched chicks it is called brooding. For the first couple weeks of life nestlings are helpless; they are unable to see, fly, or thermoregulate (maintain their own body temperature). Their mother broods them by keeping them safely under and around her in the nest.
Male owls hunt and bring food to the nest. Female owls will often tear the prey into smaller pieces and feed them to the nestlings. Owls grow quickly and within weeks begin to eat some prey whole, spit up pellets, and thermoregulate.
Nestlings compete with each other for food. Because the older nestlings are bigger and stronger than those hatched a few days later, they may get most of the meat. If food is scarce, the younger owlets may even starve to death. When the nestlings are able to maintain their body temperature, the female may leave the nest to help hunt. The nestlings cry out to their parents for food; these are called food begging calls.
FLEEING THE NEST - FLEDGING
After nestlings are capable of thermoregulation, but often before they can fly, they leave the nest and hide in the surrounding vegetation. Nestlings raised in tree nests, like Northern Hawk-Owls, climb on nearby branches until they are ready to fly. Those that nest on the ground, like Short-eared Owls, find cover in nearby grass or shrubs until they can fly. This period of exploration is called branching or nest dispersal. When nestlings first gain the ability to fly, they are called fledglings.
Short-eared owlets develop faster than any other North American species. They start to venture outside the nest when they are just two weeks old and take their first flights after 4-5 weeks. Barn Owls and Great Horned Owls are some of the slowest to develop, staying in, or near, the nest for 6 weeks or more and begin taking their first flights when 7 to 8 weeks old.
By autumn, most parents are finished raising their families. The fledglings have grown their adult feathers, and they are now full-sized owls. The young adults are ready for life on their own. Although owls have been known to live up to 25 years, the average life span for most species is probably much lower. Generally, the larger species of owls live longer than the smaller species.
Owls have three basic needs: food, somewhere safe to roost, and a place to nest. Owls live where their basic needs are met. The place where an animal naturally lives and grows is called its habitat. Forest, grassland, desert, tundra, and wooded gully habitats have plants, landforms, and animals that are important to the survival of each owl species that lives there.
Short-eared Owls, for example, require large tracts of contiguous open-country habitat, like grasslands, to survive. These habitats provide cover that hide the owls’ roosts and nest but, more importantly, provide habitat for the small rodents that Short-eared Owls eat. Southern desert habitat has saguaro cacti that Elf Owls nest in, and the insects, spiders, scorpions, and small reptiles that they eat. Great Horned Owls nest and hunt in almost every natural habitat.
When we clear out native vegetation and destroy habitat, it forces owls to move, and it means that more owls must crowd into less space. The crowded areas may not have the food supply to nourish all the owls sharing the space. Some owls may even starve.
It is important that we find a balance between our use of land and wildlife’s need for habitat. The Owl Research Institute works to inform policy and land management decisions that protect owls and their habitats. But we cannot do it without your help. Get involved with at your local level and, if possible, consider a contribution to the research and conservation we do at ORI.