Owls

Owls are some of the most fascinating and mysterious raptors in the world. While many people know a little bit about these birds of prey, some owl facts can surprise even the most experienced birders.

There Are Two Main Types of Owls

The vast majority of the roughly 200 species of owls are so-called true owls, which possess large heads with round faces, short tails, and muted feathers with mottled patterns. The remainder, accounting for a little over a dozen species, are barn owls, which can be distinguished by their heart-shaped faces, long legs equipped with powerful talons, and moderate size. With the exception of the common barn owl—which has a worldwide distribution—the most familiar owls, at least to residents of North America and Eurasia, are the true owls.

Most Owls Are Nocturnal Hunters

Evolution has an efficient way of relegating animals to particular niches: because other carnivorous birds (like hawks and eagles) hunt during the day, most owls have adapted to hunting at night. The dark coloration of owls makes them nearly invisible to their prey—which consists of insects, small mammals, and other birds—and their wings are structured so as to beat in almost complete silence. These adaptations, combined with their enormous eyes, makes owls some of the most efficient night hunters on the planet, wolves and coyotes not excluded.

You Can Tell a Lot About an Owl by its Pellets

Owls swallow their prey whole, without biting or chewing. Most of the unfortunate animal is digested, but the parts that can't be broken down—like bones, fur, and feathers—are regurgitated as a hard lump, called a "pellet," a few hours after the owl's meal. The details are a bit revolting, but by examining its pellets in detail, researchers can identify exactly what a given owl has been eating, and when. (Baby owls don't produce pellets, since their parents nourish them with soft, regurgitated food in the nest.)

Owls Aren't as Smart as You Think

In books, movies, and TV shows, owls are invariably depicted as extremely intelligent—but the fact is that it's virtually impossible to train an owl, while birds as diverse as parrots, hawks, and even pigeons can be taught to retrieve objects and memorize simple tasks. Basically, people think owls are smart for the same reason they think all kids who wear glasses are smart: bigger-than-usual eyes convey the impression of high intelligence. (This isn't to say that owls are especially dumb, either; you need lots of brain power to successfully hunt at night.)

Owls May Have Coexisted With Dinosaurs

It has proven especially difficult to trace the evolutionary origins of owls, much less their apparent kinship with contemporary nightjars, falcons and eagles. We do know that owl-like birds like Berruornis and Ogygoptynx lived 60 million years ago, during the Paleocene epoch, which means it's entirely possible that the ultimate ancestors of owls coexisted with dinosaurs toward the end of the Cretaceous period. Technically speaking, owls are one of the most ancient groups of terrestrial birds, rivaled only by the gamebirds (i.e., chickens, turkeys and pheasants) of the order Galliformes.

Owls Don't Make Very Good Pets

Leaving aside the fact that it's illegal, in the U.S. and most other countries, for private individuals to keep owls as pets, there are any number of reasons why this isn't a good idea. For one thing, owls will only eat fresh food, meaning you have to maintain a constant supply of mice, gerbils, rabbits, and other small mammals; for another, the beaks and talons of owls are very sharp, so you'll also have to keep a ready stock of band-aids; and as if all that weren't enough, an owl can live for more than 30 years, so you'll be donning your industrial-strength gloves and flinging gerbils into its cage well into late middle age.

Owls Have Had an Outsized Impact on Human Culture

Ancient civilizations had widely divergent opinions about owls. The Greeks chose owls to represent Athena, the goddess of wisdom, but Romans were terrified of this bird, considering it a bearer of ill omens. The Aztecs and Mayans hated and feared owls as symbols of death and destruction, while many Native American tribes (including Apaches and Seminoles) scared their children with stories of owls waiting in the dark to carry them away. The Egyptians, who preceded all of these civilizations, had a kinder view of owls, believing that these birds protected the spirits of the dead as they traveled to the underworld.

While the stereotype of the “wise owl” is well established, owls can be regarded as demonic symbols or harbingers of doom. Connections to witchcraft are often made as well. Owls have also risen to prominence as icons in popular culture, such as the famous Hedwig, the snowy owl featured in the Harry Potter series.

Apart from cultural significance, owls have been used by humans in the sport of falconry. Falconer’s owls may be trained to the glove and sent off in pursuit of a wide range of quarry, such as rabbits. Generally, owls are catlike birds—nocturnal and hard to train. While some of the larger owls distinguished themselves as hunting companions in Europe, their employment as falconry decoys is more common. Hated and harassed by hawks, an owl would be tethered to a perch to lure in its enemy for capture.

Weird Relatives

Owls are often referred to as “birds of prey,” but these nocturnal hunting birds share no relation to hawks, eagles, or falcons, which are known as diurnal birds of prey. Taxonomy is a controversial and changing science, but both the Sibly-Alquist model of bird classification and alternative methods identify owls as ranking closer to kingfishers, hummingbirds, and even songbirds (like sparrows) than to hawks. Hawks and other diurnal birds of prey are relegated to the more primitive reaches of avian origins, near the cranes, herons, and other prehistoric-looking birds.

Despite appearing hawklike, owls are kissing cousins of the humble nightjars, also known as “goatsuckers.” Similarities between hawks and diurnal birds of prey are apparent, especially when an owl’s feathers are parted, revealing a large, hawklike bill, but convergent evolution is the agent of cause—not relation. Nocturnal and diurnal predatory bird orders fill similar ecological niches but avoid competition by hunting within their opposite “hours of operation.”

Some Eat Plants

Owls are among the purest of carnivores in the bird world. Occupying a fraction of the world’s species total, these night hunters won’t stoop to scavenging in most cases. However, one species is rather unique in its conquest of the night. In a freak occurrence among birds, the elf owl not only feeds on small animal prey, but adds fruits and seed parts to its diet. These owls engage in a sort of “cultivation” where they spread dung around their nest sites in a bid to attract dung beetles. These enterprising “birds of prey” seem to favor prickly pear berries and the fruits of the tasajillo cactus for the not-so-predatory portion of their diet.

Many Owls Don’t Hoot Or Screech

Owls are stereotyped for their hooting calls, but a number of species don’t hoot at all. Snowy owls of the far north produce seabird-like squeaking calls that are a far cry from a typical owl call. Small owls, such as pygmy owls make dull whistling sounds. The most flagrant example is the screech owl. It doesn’t screech at all, but gives a “bouncing” series of rapid, whistling toots. The unearthly screeching calls of juvenile great horned owls often lead to false reports of a screech owl being heard.

They Live In Cacti

In North America’s Sonoran Desert, saguaro cacti can grow over 10 meters (about 30 ft) in height and form entire forests. The excavations of specially adapted woodpeckers known as gila flickers are used as nesting sites by elf owls, which peer out from the cactus with bright, yellow eyes.

The cactus forests are also inhabited by another small owl, the ferruginous pygmy owl. This far more aggressive, bird-eating owl is slightly larger and will also nest in saguaro and organ pipe cacti. Continuing the theme, huge great horned owls often nest in the crotch of such a cactus.

1. There are more than 150 species of owls in the world, and some counts indicate more than 220 species depending on how different owls are classified. The greatest owl diversity is found in Asia, and only 19 owl species are found in the United States and Canada.
2. Owls are found in all different habitats and there are different owl species found on all continents except Antarctica. The greatest diversity of owl species is found in forested habitats, but these birds can be found anywhere prey is abundant, including urban and suburban areas.
3. All owls have upright posture and forward-facing eyes that give them binocular vision, just like humans. Owls' eyes are not spheres, however, but are tubes that provide better depth perception and allow them to see prey from great distances. Up close an owl's vision is not as clear.
4. Many owl species have asymmetrical ears that are different sizes and different heights on their heads. This gives the birds superior hearing and the ability to pinpoint where prey is located, even if they can't see it.
5. Several owls species have ear tufts on their heads but they aren't ears at all. These tufts of feathers may indicate the bird's mood, help keep it camouflaged by mimicking branches or leaves, or be used to show aggression or dominance.
6. The flattened facial disk of an owl funnels sound to the bird's ears and magnifies it as much as ten times to help the owl hear noises humans can't detect. Different owls have different facial disk shapes, and that shape can be useful for identifying owls.
7. An owl's eyes are supported by bony eye sockets and they cannot turn their eyes. Instead, owls rotate their heads up to 270 degrees (135 degrees to either side), but they cannot turn their heads all the way around.
8. An owl has three eyelids: one for blinking, one for sleeping, and one for keeping the eye clean and healthy. The third eyelid is also called the nictitating membrane, and many other birds also have it, including other raptors as well as many ducks, anhingas, and dippers.
9. A barn owl can eat up to 1,000 mice each year, usually swallowing them whole. Many farmers use barn owl boxes and other tricks try to attract barn owls to help control rodent populations in agricultural fields.
10. Owls are carnivorous and will eat rodents, small or medium sized mammals, nocturnal insects, fish, and other birds, including smaller owls. After digesting their food, owls regurgitate hard pellets of compressed bones, fur, teeth, feathers, and other materials they couldn't digest. Ornithologists study those pellets to learn more about an owl's diet.
11. Owls have zygodactyl feet with two toes pointing forward and two toes pointing backward, and all their toes have sharp talons. This gives the birds a stronger, more powerful grip so they can be more effective predators. As befitting birds that hunt and kill small, skittering prey, owls are equipped with some of the strongest talons in the avian kingdom, capable of seizing and grasping squirrels, rabbits, and other squirmy mammals. One of the largest owl species, the five-pound great horned owl, can curl its talons with a force of about 300 pounds per square inch, roughly comparable to the strongest human bite. Some unusually large owls have talons comparable in size to much bigger eagles, which may explain why even desperately hungry eagles usually won't attack their smaller, big-eyed cousins.
12. Owls have specialized feathers with fringes of varying softness that help muffle sound when they fly. Their broad wings and light bodies also make them nearly silent fliers, which helps them stalk prey more easily.
13. For most owl species, females are larger, heavier, and more aggressive than males. If the birds are dimorphic, the female is often more richly colored than the male. No one is quite sure why, on average, female owls tend to be slightly larger than their male counterparts. One theory is that smaller males are more agile, and therefore more suited to catching prey while the females brood young; another is that, because females don't like to leave their eggs, they need a larger body mass to sustain themselves for long periods of time without eating. A third theory is less likely, but more amusing: since female owls often attack and drive off unsuitable males during mating season, the smaller size and greater agility of males prevent them from getting hurt.
14. Not all owls hoot, and owls can make a wide range of other sounds, such as screeches, whistles, barks, growls, rattles, and hisses. During the nesting season, owl calls can often be heard up to a mile away. Female owls generally have higher-pitched voices than their mates.
15. Not all owl species are nocturnal. How often an owl is seen during the day depends on the seasonal amount of daylight and darkness, food supplies, and habitat. In times of stress or when food is low, owls may hunt at any time, just to get enough food.
16. Most owls do not migrate but they can be nomadic in searching for the best food sources. Some species, such as the snowy owl, have regular irruptions and will sometimes appear unexpectedly far outside their regular range.
17. A group of owls is called a parliament, wisdom, bazaar, or study. Baby owls are called owlets.
18. Owls have been found in the fossil record up to 58 million years ago. The largest recorded owl fossil, Orinmegalonyx oteroi, stood about three feet tall.
19. Owls have long been cultural symbols and they have been found in cave paintings in France, in Egyptian hieroglyphics, and even in Mayan art. Today, owl superstitions and legends associate the birds with bad luck, death, and stealing souls in many cultures.
20. The biggest modern threats to owls are habitat loss, pesticides that poison the birds and their food supplies, and human persecution because of negative superstitions. Vehicle collisions, wire fences, and even well-meaning birders can also be hazardous to owls.
21. Many owl species have asymmetrical ears. When located at different heights on the owl’s head, their ears are able to pinpoint the location of sounds in multiple dimensions. Ready, aim, strike.
22. A group of owls is called a parliament. This originates from C.S. Lewis’ description of a meeting of owls in The Chronicles of Narnia.
23. Owls hunt other owls. Great Horned Owls are the top predator of the smaller Barred Owl.
24. The tiniest owl in the world is the Elf Owl, which is 5 - 6 inches tall and weighs about 1 ½ ounces. The largest North American owl, in appearance, is the Great Gray Owl, which is up to 32 inches tall.
25. The Northern Hawk Owl can detect—primarily by sight—a vole to eat up to a half a mile away.
26. In fat years when mice are plentiful, usually monogamous Boreal Owls are apt to be promiscuous. Because easy prey means less work for parents feeding their young, males have been caught mating with up to three females, while females have been seen with at least one beau on the side.
27. Barn Owls swallow their prey whole—skin, bones, and all—and they eat up to 1,000 mice each year.
28. Northern Saw-whet Owls can travel long distances over large bodies of water. One showed up 70 miles from shore near Montauk, New York.