After the sun goes down, daytime birds turn over the airwaves to an eerier night shift. Of all the bazaar avian voices darkness conjures, few can fill a forest with nocturnal ambience quite like an owl.
Owls date back 50 million years or more and now inhabit every continent except Antarctica, ranging from the tundra to the tropics. Some are active by day, but most—the vast majority of 250 known species—are nocturnal or crepuscular. People rarely see owls because of their stealthy habits, so we rely on their ethereal hoots, strange chirps, or terrifying screeches to make us aware of their presence.
Indeed, these birds emit a wide range of noises, some easier to recognize than others. Here's a "who's who" of some commonly heard owls with hopes of making these moonlight crooners a little less mysterious.
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Barred Owl
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The barred owl (Strix varia) is famous for a distinctive series of hoots traditionally anglicized to "Who cooks for you? Who cooks for you all?"
These owls are abundant in North America east of the Mississippi River, especially in old-growth forests and treed swamps. They're adaptable, too, inhabiting some urban areas with enough old tree cavities suitable for nesting. Barred owls have also expanded across parts of Canada into the Pacific Northwest, where they can outcompete the similar-looking but much rarer spotted owl.
A typical "who cooks" call consists of eight or nine warbling hoots, although barred owls seem to give themselves a fair amount of artistic license.
Mated pairs also perform a howling treetop opera of caterwauls and "monkey calls," described by the Cornell Lab of Ornithology as a "riotous duet of cackles, hoots, caws, and gurgles." Here's an example recorded in Berkeley County, West Virginia.
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Great Horned Owl
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Haunting diverse habitats from Alaska to Argentina, great horned owls (Bubo virginianus) are the most common owls in the Americas. And thanks to their piercing yellow eyes, imposing size, and distinctive ear tufts—technically "plumicorns," not horns—they're also one of the most iconic New World raptors.
Great horned owls hunt mainly at night, tackling prey ranging from mice, frogs, and snakes to rabbits, skunks, crows, and geese. They can be recognized by a chain of "low, sonorous, far-carrying hoots, hoo, hoo-hoo, hoo, hoo," according to the National Audubon Society, "with second and third notes shorter than the others."
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Barn Owl
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The common barn owl (Tyto alba) is one of Earth's most widely distributed land birds, found on all continents but Antarctica. It hails from the family Tytonidae, one of two main lineages of modern owls. (All other owls in this list are from the more diverse Strigidae family, known as "true owls.") Like other Tytonidae species, T. alba has large, dark eyes and a characteristic heart-shaped facial disk.
Barn owls hunt rodents at night by soaring over open land like marshes, prairies, or farms, or by scanning from a low perch. They roost and nest in quiet cavities, including trees as well as barns, silos, and church belfries. They're strictly nocturnal but don't hoot—instead, their signature call is a raspy, drawn-out scream.
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Eurasian Eagle Owl
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With a wingspan of nearly six and a half feet, the Eurasian eagle owl (Bubo bubo) is one of the largest owl species on the planet. It lives throughout much of Europe, Asia, and North Africa, where it preys on a variety of animals—even mammals as large as adult foxes or young deer—apparently fearing no natural predators of its own.
Eagle owls are most active at night. Their primary call is deep and booming, although each bird puts its own individual twist on the species' soundtrack. In fact, every member of the Eurasian eagle owl population can be reliably identified by voice alone.
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Scops Owl
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Scops owls are true owls in the genus Otus, with about 58 known species across the world. They're small and agile, usually six to 12 inches tall, and use camouflaged feathers to blend in with tree bark. Calls vary by species, but most make a string of high-pitched hoots, fewer than five per second, or a long, single whistle.
The Eurasian scops owl (Otus scops) is one common species, found in parts of southern Europe, North Africa, Asia Minor, the Arabian Peninsula, and Central Asia. Like other scops owls, its small size makes it vulnerable to predators, so it hides itself in trees during the day. At night, it hunts insects, songbirds, and other small prey.
Here's a recording of O. scops hooting near Mattersburg, Austria, followed by another widespread species, the oriental scops owl (O. sunia).
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Screech Owl
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For such big-voiced birds, screech owls are surprisingly small. About 23 species are known to science, all in the Americas, filling a niche similar to Old World scops owls. They rely on camouflage to hide in trees during the day, then come alive at night.
The eastern screech owl (Megascops asio) is about the size of a robin, and ranges across most of the Eastern and Midwestern U.S., from the Great Plains to Atlantic coasts. Despite its name, it doesn't really screech, instead producing whinnies and trills. The male's main call (A-song) is a mellow trill that fits several dozen notes into a few seconds, and his B-song is a descending whinny.
The western screech owl (Megascops kennicottii) ranges from southeastern Alaska to the Arizona desert, and while it bears a visual resemblance to its eastern cousin, it sounds significantly different. The species makes "an accelerating 'bouncing ball' series" of six to eight whistles, according to the Audubon Society.
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Great Gray Owl
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The great gray owl (Strix nebulosa) is the largest owl in North America, standing more than two feet tall with a wingspan up to five feet. But "its great size is partly an illusion," the Audubon Society points out, thanks to a fluffy mass of feathers that envelop a much smaller body. Great gray owls are lighter than great horned or snowy owls, and they have relatively diminutive feet and talons.
These rodent specialists can hunt by hearing alone, often diving to grab mice from underneath deep snow. They're most active at night and can be identified by a deep "hooo-ooo-ooo-ooo" bellowed slowly over several seconds. Territorial calls begin after dusk, peak before midnight, and then again later in the night. They can be heard up to half a mile away on clear nights.
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Tawny Owl
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About the size of a pigeon, tawny owls are widespread across Europe. They're the most common owls in Britain, where they're also known as "brown owls." Their range extends to North Africa, Iran, western Siberia, the Himalayas, southern China, and Taiwan. In 2005, there were about 50,000 breeding pairs just in the U.K.
The species starts forming territories in the fall. They tend to nest in tree cavities, swooping from perches to grab small prey like earthworms, beetles, and voles at night.
Males' primary call, used in claiming territory as well as courtship, is a series of spaced-out "hoohoo" sounds. Females can respond with a similar hoot, but they more often make the "kewick" contact call. This 2014 recording from Norfolk, England, features a male calling to a distant female.
Why Are Owls So Vocal at Night?
Owls hoot, scream, and call out at night for the same reason birds chirp and sing: to establish and protect their territory, to woo females, and to signal the presence of a predator, among other reasons. The only reason they're so vocal in the dark is because most owls are nocturnal or at least crepuscular.
Owls are are well-equipped for night life, thanks to key adaptations for finding and catching prey in almost total darkness. Their light-sensitive "eye tubes" and sound-funneling face feathers help them detect movement, for example, and they can fly in virtual silence thanks to big wings and specially shaped flight feathers.
