Owl

Owls are birds from the order Strigiformes. There are over 200 kinds of owls. Most owls live alone and are solitary. Most hunt at night, so they are nocturnal. They are birds of prey, which means they hunt other animals for food. Owls stand up tall and have large, broad heads. They can see straight ahead with binocular vision and hear with binaural hearing. They have sharp talons on their feet. Their feathers let them fly very quietly. A few owls are active during the day, like the northern hawk-owl. The burrowing owl is one kind that lives in groups.

Owls are split into two families. The true owls, also called typical owls, belong to the Strigidae family. The barn owl and bay owl belong to the Tytonidae family. Owls mostly hunt small mammals, insects, and other birds. A few kinds hunt fish. Owls live in almost every part of the world. They are not found at the polar ice caps or on some far-away islands.

In English venery, a group of owls is called a "parliament."

For other uses, see Owl (disambiguation).

Anatomy

Owls have large eyes that face forward, ear openings, and a hawk-like beak. Their flat face has a facial disc, a ring of feathers around each eye, which helps guide sound to their ears. Their forward-facing eyes give them depth perception and binocular vision, which help them hunt in low light. Their eyes cannot move in their sockets, so they turn their heads to look around. An owl's head can turn about 270 degrees. Owls have 14 neck bones, while humans have seven. Special blood vessels let them turn their heads without cutting off blood to the brain. The foramina in their cervical vertebrae are large, and their carotid arteries join at a large anastomosis. Owls can also feel prey with filoplumes, which are hair-like feathers on the beak and feet. Their feathers have smooth edges shaped by rachis structures. The serrated edges of the flight feathers, called remiges, make their wings nearly silent. This helps them catch prey that might otherwise hear them coming.

Owls come in many sizes. The elf owl can weigh as little as 31 grams, while large species include the Eurasian eagle-owl and Blakiston's fish owl. Other tiny owls include the long-whiskered owlet and the Tamaulipas pygmy owl. Different calls help owls find mates and warn rivals. Calls also help ornithologists and birders tell species apart. Most owl plumage is cryptic, which means it helps owls blend into their surroundings. Examples include the snowy owl, tawny owl, and mottled wood owl. Some owls have ear tufts or brightly colored irises. Owls do not use echolocation to fly in the dark. Their tube-shaped eyes are like those of strepsirrhine primates and bathypelagic fishes, so they turn their heads to look around instead. Female owls are usually larger than males. One idea is that smaller males can be efficient foragers.

Barn owls, such as the barn owl, have feathers that are not waterproof. They also do not spread oil from their uropygial gland as most birds do, so heavy rain can stop them from hunting. They may hunt in barns during wet weather. They can also drown in drinking troughs, so the Barn Owl Trust advises fitting floats. Owls like the great horned owl and Tasmanian masked owl have strong, sharp talons for holding prey.

Further information: Sound localization in owls

Behavior

Most owls are nocturnal, which means they hunt at night. Some, like the pygmy owls (Glaucidium), are crepuscular and are active at dawn and dusk. A few owls, such as the burrowing owl (Speotyto cunicularia) and the short-eared owl (Asio flammeus), are also active during the day. Owls rely on stealth and surprise when they hunt. Their feathers are often dull in color, which can help them blend in and be hard to see in some places. The edges of the remiges (the long flight feathers) are shaped like tiny teeth. This makes their wings quiet, so most owls fly almost silently. Some fish-eating owls do not fly quietly, because silence does not help them catch fish.

An owl has a sharp beak and strong talons that help it catch and kill its prey. It swallows small prey whole. Owls often bring up the parts they cannot digest, such as bones, scales, and fur, as pellets. These owl pellets are easy to find and study, so scientists use them to learn what owls eat. Companies also sell owl pellets to schools, where students take them apart as a biology and ecology lesson. Owl eggs are usually white and almost round. A female owl usually lays between a few and a dozen eggs, depending on the species and season, and three or four is most common.

Evolution and systematics

Scientists who study how living things are related place owls in a large group of birds called Telluraves. Owls are most closely related to the Accipitrimorphae and the Coraciimorphae, but scientists still argue about their exact place in this group. A cladogram is a diagram that shows these relationships.

About 220 to 225 owl species are alive today. They belong to two families. The true owls, also called typical owls, are in the family Strigidae. Barn owls are in the family Tytonidae.

Owls became a separate group about 60 to 57 million years ago. This may have happened even earlier, around 5 million years before that, when the dinosaurs that were not birds died out. This makes owls one of the oldest known groups of landbirds that are not Galloanserae. Fossils show that many other owl-like birds lived long ago. Some looked very different from owls today, such as the ground-living Sophiornithidae.

During the Paleogene, owl-like birds spread into many ecological niches. The owls we know today developed their special morphology and adaptations at that time. By the early Neogene, only barn owls and typical owls were left, because other groups of birds had taken over their places. Early typical owls looked fairly plain, a bit like today's spotted owl or tawny owl. Their wide range of sizes and ecology developed later. For a full list of owls that are alive today or died out recently, see List of owl species.

Symbolism and mythology

Owls have been linked with both good and bad meanings in many cultures. Among the Kikuyu of Kenya, owls were believed to bring bad news, and people often see them as signs of bad luck, sickness, or death. In Hinduism, an owl is the vahana (mount) of the goddess Lakshmi. It is a symbol of wealth, good luck, and wisdom, though owls are also linked with hard times. Chamunda, a fierce form of Chandi, is shown sitting on her vahana. In China, owls are often seen as a sign of bad luck, but they are also a symbol of good luck. In Japan, people think of them as lucky, although long ago they were linked with death. In Sumerian, Akkadian, and Babylonian culture, the owl was connected with Lilith. The modern West often links owls with wisdom and vigilance. This idea goes back at least to Ancient Greece, where Athens and its goddess Athena used the owl as a symbol. Marija Gimbutas traces the owl's honor as a goddess to the culture of Old Europe, which came long before Indo-European cultures. In medieval Europe, owls were linked with darkness, sadness, and the bubonic plague. In 1883, T. F. Thiselton-Dyer noted that the owl had long been seen as a bird of bad omen. Pliny described how Rome once had to hold a lustration, a special cleansing ceremony, after an owl flew into the Capitol. Virgil linked an owl's cry with the death of Dido, and Ovid often described the bird as a sign of bad things to come.

Many Native American peoples also connected owls with danger and death. Some parents told misbehaving children, "the owls will get you." The Apache and Seminole tribes told bogeyman stories about owls to warn children to stay inside at night. Some tribal legends linked owls with spirits of the dead. The Aztecs and the Maya, along with other peoples of Mesoamerica, saw the owl as a symbol of death and destruction. The Aztec god of death, Mictlantecuhtli, was often shown with owls. An old saying in Mexico also connects the owl with death. The Popol Vuh, a Mayan religious text, describes owls as messengers of Xibalba. The Hočągara (Winnebago) also believed owls were messengers of dark powers. They said an owl spoke to them and foretold the decline of their tribe. An owl also called out the name of Glory of the Morning, the only female chief of the Hočąk nation, and soon after, she died. In Hopi traditions, owls can be linked with the underworld and death. The Ojibwe and their Aboriginal Canadian relatives used the owl as a symbol of evil and death, but also of the high status of spiritual leaders. The Pawnee saw owls as protectors from danger. The Puebloan peoples linked owls with Skeleton Man, the god of death and the spirit of fertility. The Yakama use an owl as a totem to guide how forests and natural resources are cared for.

Rodent control

Natural pest control means using animals that eat pests, such as owls, and keeping food away from rodents. A nest box for owls on a property can help control rodent numbers. A family of barn owls can eat many rodents during one nesting season, which helps keep nature in balance.

Conservation issues

See also: List of Strigiformes by population

Almost all owls are listed in Appendix II of CITES, an international agreement that helps protect wild animals and plants. Four owl species are listed in Appendix I. Owls have long been hunted. A 2008 news story from Malaysia suggests that illegal owl poaching may be increasing. In November 2008, TRAFFIC reported seizing 900 owls in Peninsular Malaysia. A similar raid in January 2009 seized 319 owls. Other protected animals were also taken, including barn owls, spotted wood owls, brown wood owls, crested serpent eagles, and more than 7,000 live clouded monitor lizards.

Hunting is not the only danger to owls. Other threats include habitat loss, pesticides, viruses, and collisions with vehicles. The use of rodenticides is a common cause of death for many birds of prey, including owls. Owls that eat animals affected by these chemicals can become sick and may die. Studying owls is also difficult. Most owls are active at night and are well camouflaged, and they often live in places that are hard for researchers to reach. Scientists sometimes use sound recordings to track owls, but collecting population information is still a challenge for conservation work.