Owl
Overview
Owls are a group of birds that belong to the order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 Strigiformes, constituting 200 bird of prey
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....

 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

. Most are solitary and nocturnal
Nocturnal animal
Nocturnality is an animal behavior characterized by activity during the night and sleeping during the day. The common adjective is "nocturnal"....

, with some exceptions (e.g. the Northern Hawk Owl
Northern Hawk Owl
The Northern Hawk-Owl is a non-migratory owl that usually stays within its breeding range. It sometimes irrupts southward.-General:It is the only living species in the genus Surnia...

). Owls hunt mostly small mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s, insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s, and other birds, although a few species specialize in hunting fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

. They are found in all regions of the Earth except Antarctica, most of Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...

 and some remote islands.
Encyclopedia
Owls are a group of birds that belong to the order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 Strigiformes, constituting 200 bird of prey
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....

 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

. Most are solitary and nocturnal
Nocturnal animal
Nocturnality is an animal behavior characterized by activity during the night and sleeping during the day. The common adjective is "nocturnal"....

, with some exceptions (e.g. the Northern Hawk Owl
Northern Hawk Owl
The Northern Hawk-Owl is a non-migratory owl that usually stays within its breeding range. It sometimes irrupts southward.-General:It is the only living species in the genus Surnia...

). Owls hunt mostly small mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s, insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s, and other birds, although a few species specialize in hunting fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

. They are found in all regions of the Earth except Antarctica, most of Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...

 and some remote islands. Though owls are typically solitary, the literary collective noun for a group of owls is a parliament.
Living owls are divided into two families
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

: the typical owl
Typical owl
True owl or Typical owl are one of the two generally accepted families of Owls, the other being the barn owls . The Sibley-Ahlquist taxonomy unites the Caprimulgiformes with the owl order; here, the typical owls are a subfamily Strigidae...

s, Strigidae; and the barn-owls, Tytonidae.

Description

Owls have large forward-facing eyes and ear-holes; a hawk
Hawk
The term hawk can be used in several ways:* In strict usage in Australia and Africa, to mean any of the species in the subfamily Accipitrinae, which comprises the genera Accipiter, Micronisus, Melierax, Urotriorchis and Megatriorchis. The large and widespread Accipiter genus includes goshawks,...

-like beak
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...

; a flat face; and usually a conspicuous circle of feathers, a facial disc
Facial disc
In ornithology, the facial disc is the concave collection of feathers on the face of some birds—most notably owls—surrounding the eyes. The concavity of the facial disc forms a circular paraboloid that collects sound waves and directs those waves towards the owl's ears...

, around each eye. The feathers making up this disc can be adjusted in order to sharply focus sounds that come from varying distances onto the owls' asymmetrically placed ear cavities. Most birds of prey sport eyes on the sides of their heads, but the stereoscopic nature of the owl's forward-facing eyes permits the greater sense of depth perception necessary for low-light hunting. Although owls have binocular vision
Binocular vision
Binocular vision is vision in which both eyes are used together. The word binocular comes from two Latin roots, bini for double, and oculus for eye. Having two eyes confers at least four advantages over having one. First, it gives a creature a spare eye in case one is damaged. Second, it gives a...

, their large eyes are fixed in their sockets — as are those of other birds — so they must turn their entire head to change views. Owls can rotate their heads and necks as much as 270 degrees in either direction. As owls are farsighted, they are unable to see clearly anything within a few centimeters of their eyes. Caught prey can be felt by owls with the use of filoplumes — like feathers on the beak and feet that act as "feelers". Their far vision, particularly in low light, is exceptionally good.

The smallest owl — weighing as little as 31 g (1.1 oz) and measuring some 13.5 cm (5.3 inches) — is the Elf Owl
Elf Owl
The Elf Owl is a member of the owl family Strigidae that breeds in the southwestern United States and Mexico. It is the world's lightest owl, although the Long-whiskered Owlet and the Tamaulipas Pygmy Owl are of a similarly diminutive length. The mean body weight of this species is 40 grams...

 (Micrathene whitneyi). Some of the pygmy owl
Pygmy owl
Pygmy Owls are members of the genus Glaucidium. They belong to the typical owl family Strigidae, one of the two generally accepted living families of owls....

s are scarcely larger. The largest is the Great Grey Owl
Great Grey Owl
The Great Grey Owl or Lapland Owl is a very large owl, distributed across the Northern Hemisphere. In some areas it is also called the Great Gray Ghost, Phantom of the north, Cinereous Owl, Spectral Owl, Lapland Owl, Spruce Owl, Bearded Owl and Sooty Owl.-Description:Adults have a big, rounded...

 with 72 centimeters average, the second and third largest are two of the eagle owls
Horned owl
The American horned owls and the Old World eagle-owls make up the genus Bubo, at least as traditionally described. This genus, depending on definition, contains about one or two dozen species of typical owls and is found in many parts of the world. Some of the largest living Strigiformes are in...

; the Eurasian Eagle-Owl (Bubo bubo) and Blakiston's Fish Owl (Bubo blakistoni) — which may reach a size of 60 – 71 cm (28.4 in) long, and have a wingspan of almost 2 m (6.6 ft), and an average weight of nearly 4.5 kg (10 lb).).

Different species of owls make different sounds; this wide range of calls aids owls in finding mates or announcing their presence to potential competitors, and also aids ornithologists and birders in locating these birds and recognizing species. As noted above, the facial disc helps owls to funnel the sound of prey to their ears. In many species, these discs are placed asymmetrically, for better directional location.

The plumage
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...

 of owls is generally cryptic, but many species have facial and head markings, including face masks, ear tufts and brightly coloured iris
Iris (anatomy)
The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...

es. These markings are generally more common in species inhabiting open habitats, and are thought to be used in signaling with other owls in low light conditions.

Owl eggs usually have a white color and an almost spherical shape, and range in number from a few to a dozen, depending on species. Eggs are laid at intervals of 1 to 3 days and do not hatch at the same time. This fact accounts for the wide variation in the size of sibling nestlings. Owls do not construct nests, but rather look for a sheltered nesting site or an abandoned nest in trees, underground burrows, or in buildings, barns and caves.

Behavior

Most owls are nocturnal, actively hunting their prey only in water and
darkness. Several types of owl, however, are crepuscular
Crepuscular
Crepuscular animals are those that are active primarily during twilight, that is during dawn and dusk. The word is derived from the Latin word crepusculum, meaning "twilight." Crepuscular is, thus, in contrast with diurnal and nocturnal behavior. Crepuscular animals may also be active on a bright...

 — active during the twilight hours of dawn
Dawn
Dawn is the time that marks the beginning of the twilight before sunrise. It is recognized by the presence of weak sunlight, while the sun itself is still below the horizon...

 and dusk
Dusk
Dusk is the beginning of darkness in the evening, and occurs after twilight, when the sky generally remains bright and blue. Civil dusk is when the earth has rotated enough that the center of the sun is at 6° below the local horizon...

; one example is the Pygmy owl
Pygmy owl
Pygmy Owls are members of the genus Glaucidium. They belong to the typical owl family Strigidae, one of the two generally accepted living families of owls....

 (Glaucidium). A few owls are active during the day also; examples are the Burrowing Owl
Burrowing Owl
The Burrowing Owl is a tiny but long-legged owl found throughout open landscapes of North and South America. Burrowing Owls can be found in grasslands, rangelands, agricultural areas, deserts, or any other open dry area with low vegetation. They nest and roost in burrows, such as those excavated...

 (Speotyto cunicularia) and the Short-eared Owl
Short-eared Owl
The Short-eared Owl is a species of typical owl . In Scotland this species of owl is often referred to as a cataface, grass owl or short-horned hootlet. Owls belonging to genus Asio are known as the eared owls, as they have tufts of feathers resembling mammalian ears. These "ear" tufts may or may...

 (Asio flammeus).
Much of the owls' hunting strategy depends on stealth and surprise. Owls have at least two adaptations that aid them in achieving stealth. First, the dull coloration of their' feathers can render them almost invisible under certain conditions. Secondly, serrated edges on the leading edge of owls' remiges muffle an owl's wing beats, allowing an owl's flight to be practically silent. Some fish-eating owls, for which silence has no evolutionary advantage, lack this adaptation.

An owl's sharp beak
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...

 and powerful talons allow it to kill its prey before swallowing it whole (if it is not too big). Scientists studying the diets of owls are helped by their habit of regurgitating
Regurgitation (digestion)
Regurgitation is the expulsion of material from the mouth, pharynx, or esophagus, usually characterized by the presence of undigested food or blood.Regurgitation is used by a number of species to feed their young...

 the indigestible parts of their prey (such as bones, scales and fur) in the form of pellets
Pellet (ornithology)
A pellet, in ornithology, is the mass of undigested parts of a bird's food that some bird species occasionally regurgitate. The contents of a bird's pellet depend on its diet, but can include the exoskeletons of insects, indigestible plant matter, bones, fur, feathers, bills, claws, and teeth...

. These "owl pellets" are plentiful and easy to interpret, and are often sold by companies to schools for dissection by students as a lesson in biology and ecology.

Adaptations for hunting

All owls are carnivorous birds of prey and live mainly on a diet of insects and small rodents such as mice, rats and hares. Some owls are also specifically adapted to hunt fish. They are very adept in hunting in their respective environments. Since owls can be found in nearly all parts of the world and across a multitude of ecosystems, their hunting skills and characteristics vary slightly from species to species, though most characteristics are shared among all species.

Flight and feathers

Most owls share an innate ability to fly almost silently and also more slowly in comparison to other birds of prey. Most owls live a mainly nocturnal lifestyle and being able to fly without making any noise gives them a strong advantage over their prey that are listening for any sign of noise in the dark night. A silent, slow flight is not as necessary for diurnal and crepuscular owls given that prey can usually see an owl approaching. While the morphological and biological mechanisms of this silent flight are more or less unknown, the structure of the feather has been heavily studied and accredited to a large portion of why they have this ability. Owls’ feathers are generally larger than the average birds’ feathers, have fewer radiates, longer pennulum, and achieve smooth edges with different rachis
Rachis
Rachis is a biological term for a main axis or "shaft".-In zoology:In vertebrates a rachis can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the rachis usually form the supporting axis of the body and is then called the spine or vertebral column...

 structures. Serrated edges along the owl’s remiges bring the flapping of the wing down to a nearly silent mechanism. Research has shown that the serrations are more likely reducing aerodynamic disturbances, rather than simply reducing noise. The surface of the flight feathers are covered with a velvety structure which absorbs the sound of the wing moving. These unique structures reduce noise frequencies above 2 kHz, making the sound level emitted drop below the typical hearing spectrum of the owl’s usual prey. and also within the owl’s own best hearing range [4,5]. This optimizes the owl’s ability to silently fly in order to capture prey without the prey hearing the owl first as it flies in. It also allows the owl to monitor the sound output from its flight pattern.

Vision

Another characteristic of the owl which aids in their nocturnal prey capture is their eyesight. Owls are part of a small group of birds that live nocturnally, but do not use echolocation to guide them in flight in low-light situations. Owls are known for their disproportionally large eyes in comparison to their skull. An apparent consequence of the evolution of an absolutely large eye in a relatively small skull is that the eye of the owl has become tubular in shape. This shape is found in other so-called nocturnal eyes, such as the eyes of prosimian
Prosimian
Prosimians are a grouping of mammals defined as being primates, but not monkeys or apes. They include, among others, lemurs, bushbabies, and tarsiers. They are considered to have characteristics that are more primitive than those of monkeys and apes. Prosimians are the only primates native to...

s and bathypelagic fishes. Since the eyes are fixed into these sclerotic tubes, they are unable to move the eyes in any direction. Instead of moving their eyes, owls swivel their head to visualize their surroundings. The swiveling radius of the owl’s head is around 270˚, easily enabling them to see behind them without relocating the torso. This ability keeps bodily movement at a minimum and thus reduces the amount of sound the owl makes as it waits for its prey. Owls are regarded as having the most frontally placed eyes amongst all avian groups, which gives them some of the largest binocular fields of vision. But owls are farsighted and cannot focus on objects within a few centimeters of their eyes. While it is commonly believed that owls have such great nocturnal vision due to their large (and thus very light-gathering) eyes and pupils and/or extremely sensitive rod receptors, the true cause for their ability to see in the night is due to neural mechanisms which mediate the extraction of spatial information gathered from the retinal image throughout the nocturnal luminance range. These mechanisms are only able to function due to the large sized retinal image. Thus, the primary nocturnal function in the vision of the owl is due to its large posterior nodal distance; retinal image brightness is only maximized to the owl within secondary neural functions. These attributes of the owl cause the nocturnal eyesight to be far superior to that of its average prey.

Hearing

Owls exhibit specialized hearing functions and ear shapes that also aid in hunting. They are often noted for the asymmetrical ear placements on the skull in some genera. Owls can have either internal or external ears, but the genera exhibiting asymmetrical ear geometry only have external ear placements. Asymmetry has not been reported to extend to the middle or internal ear of the owl. The asymmetrical ear placement on the skull allows the owl to pinpoint the location of its prey. This is especially true with the strictly nocturnal species such as the barn owls Tyto or Tengmalm’s Owl. With the ears set at different places on the skull, the owl is able to determine the direction in which the sound is coming from by the minute difference in time that it takes for the sound waves to penetrate the left and right ear. The owl turns its head until the sound reaches both ears simultaneously, at which point it is directly facing the source of the sound. This time difference between ears is a matter of about 0.00003 seconds, or 30 millionths of a second. In coordination with this left to right calibration, some owls (like the barn owl) have slightly asymmetrical ears up and down that allow the owl to recognize whether the sound being received is higher or lower in vertical space by the volume of the sound in each ear. If the sound is louder in the ear facing more upwards, then the prey is higher up than the owl’s focus. Like the eyes, that utilize feather movements to focus light, the ears are surrounded by feathers to maximize hearing capabilities. Behind the ear openings there are modified, dense feathers which are densely packed to form facial ruff which creates an anteriorly-facing concave wall which cups the sound into the ear structure. This facial ruff is poorly defined in some species and yet prominent and nearly encircling the face in other species. The facial disk also acts to direct sound into the ears and a downward-facing, sharply triangular beak allows for little sound reflection away from the face. The shape of the facial disk is able to be adjusted at will to focus sounds more effectively. Owls have an audible range similar to that of humans, but are far more acute to certain frequencies which allow it to detect even the slightest movements of its prey. Once the owl has determined the location of its prey, it flies towards it according to the last sound perceived. If the prey moves, the owl is able to adjust its flight pattern mid-flight.

Talons

While the auditory and visual capabilities of the owl allow it to locate and pursue its prey, the talon and beak of the owl does the final work. The owl’s prey is killed by using these talons to crush the skull and knead the body. The crushing power of an owl’s talon varies according to prey size and type as well the size of the owl itself. The Burrowing Owl (Athene cunicularia), a small partly insectivorous owl, has a release pressure of only 500 grams. The larger Barn Owl (Tyto alba) needs pressure of 3000 grams to release its prey, and one of the largest owls, the Great Horned Owl (Bubo virginianus) needs pressure of over 13,000 grams to release prey in its talons. An owl’s talons, like most birds of prey, can seem massive in comparison to the body size outside of flight. The Masked owl has some of the proportionally longest talons of any bird of prey and appears enormous in comparison to the body when fully extended to grasp prey. The foot design of owls differs from that of diurnal birds of prey because owls have a zygodactyl toe arrangement, with two toes directed forwards and two toes directed backwards during perching. During flight, the outer front toe swivels forwards due to a flexible joint so that three of the four toes are forward facing. Some owls’ talons have been adapted to include filoplume feathers that aid in sensing the prey once it is close or has in fact made contact with the talon, which is useful during the capturing of small prey at night. The underside of the talon foot is covered in a rough, knobby surface which allows the owl to grasp its prey and hold it without having to keep the muscles tightly contracted. An owl’s claws are sharp and curved. The family Tytonidae have inner and central toes of about equal length while the family Strigidae have an inner toe which is distinctly shorter than the central one. These different morphologies allow for more effective capturing to prey specific to the different environments in which they inhabit.

Beak

The beak of the owl is short, curved and downward-facing. The beak is typically hooked at the tip for gripping and tearing its prey. Once prey is captured, the scissor motion of the top and lower bill is used to tear the tissue and kill. The sharp lower edge of the upper bill works in coordination with the sharp upper edge of the lower bill to deliver this motion. The downward-facing beak allows to the owl’s field of vision to be clear, as well as direct sound into the ears without deflecting sound waves away from the face.

Camouflage

The coloration of the owl’s plumage plays a key role in its ability to sit dormant and blend into the environment, making themselves nearly invisible to prey. Owls tend to mimic the colorations and sometimes even the texture patterns of their surroundings, with the common barn owl being an exception. Nyctea scandiaca, or the White Owl, appears nearly bleach-white in color with a few flecks of black which mimic their snowy surroundings perfectly. Likewise, the Muted Wood-Owl (Strix ocellata) displays shades of brown, tan and black which make the owl nearly invisible in the surrounding trees, especially from behind. Usually, the only tell-tale sign of a perched owl will be vocalization outside of a hunt or their vividly colored eyes.

Evolution and systematics

The systematic placement
Systematics
Biological systematics is the study of the diversification of terrestrial life, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees...

 of owls is disputed. For example, the Sibley-Ahlquist taxonomy
Sibley-Ahlquist taxonomy
The Sibley-Ahlquist taxonomy is a bird taxonomy proposed by Charles Sibley and Jon Edward Ahlquist. It is based on DNA-DNA hybridization studies conducted in the late 1970s and throughout the 1980s....

 finds that, based on DNA-DNA hybridization, owls are more closely related to the nightjar
Nightjar
Nightjars are medium-sized nocturnal or crepuscular birds with long wings, short legs and very short bills. They are sometimes referred to as goatsuckers from the mistaken belief that they suck milk from goats . Some New World species are named as nighthawks...

s and their allies (Caprimulgiformes
Caprimulgiformes
The Caprimulgiformes is an order of birds that includes a number of birds with global distribution . They are generally insectivorous and nocturnal...

) than to the diurnal predators in the order Falconiformes
Falconiformes
The order Falconiformes is a group of about 290 species of birds that comprises the diurnal birds of prey. Raptor classification is difficult and the order is treated in several ways.- Classification problems :...

; consequently, the Caprimulgiformes are placed in the Strigiformes, and the owls in general become a family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Strigidae. A recent study indicates that the drastic rearrangement of the genome of the accipitrids may have obscured any close relationship of theirs with groups such as the owls.
In any case, the relationships of the Caprimulgiformes, the owls, the falcon
Falcon
A falcon is any species of raptor in the genus Falco. The genus contains 37 species, widely distributed throughout Europe, Asia, and North America....

s and the accipitrid raptors
Accipitridae
The Accipitridae, one of the two major families within the order Accipitriformes , are a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-sized mammals, with a number feeding on carrion and a...

 are not resolved to satisfaction; currently there is an increasing trend to consider each group (with the possible exception of the accipitrids) a distinct order.

There are some 220 to 225 extant species of owls, subdivided into two families: typical owls (Strigidae) and barn-owls (Tytonidae). Some entirely extinct families have also been erected based on fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

 remains; these differ much from modern owls in being less specialized or specialized in a very different way (such as the terrestrial Sophiornithidae
Sophiornithidae
Sophiornithidae , was a family of chicken-sized predatory birds that lived from the Paleocene to the Eocene periods of the Cenozoic, and were found primarily in Europe, and are thought to be primitive owls...

). The Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...

 genera Berruornis
Berruornis
Berruornis orbisantiqui was an early fossil owl or owl-like bird recovered from late Paleocene deposits in the region of Reims in northeastern France. It was about the size of a Eurasian Eagle-owl ....

 and Ogygoptynx
Ogygoptynx
Ogygoptynx is an extinct genus of owl from the Paleocene.-References:*Rich, Patricia Vickers & David J. Bohaska, 1981. The Ogygoptyngidae, a New Family of Owls from the Paleocene of North America. Alcheringa 5: 95-102....

 show that owls were already present as a distinct lineage some 60 - 57 mya (million years ago), and, hence, possibly also some 5 million years earlier, at the extinction of the non-avian dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s. This makes them one of the oldest known groups of non-Galloanserae landbirds. The supposed "Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 owls" Bradycneme
Bradycneme
Bradycneme is a genus of theropod dinosaur from the early Maastrichtian-age Upper Cretaceous Sânpetru Formation of the Haţeg Basin, Transylvania, Romania. It is known only from a partial right lower leg , which its describers believed came from a giant owl.-History:Harrison and Walker described...

 and Heptasteornis
Heptasteornis
Heptasteornis is the name given to a dubious genus of small dinosaur from the Late Cretaceous. The type species is Heptasteornis andrewsi, described as a presumed gigantic prehistoric owl in 1975...

 are apparently non-avialan
Avialae
Avialae is a clade of dinosaurs containing their only living representatives, birds , and the most immediate extinct relatives of birds.-Competing definitions:...

 maniraptors
Maniraptora
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the dinosaurs that were more closely related to them than to Ornithomimus velox. It contains the major subgroups Avialae, Deinonychosauria, Oviraptorosauria and Therizinosauria. Ornitholestes and the Alvarezsauroidea...

.

During the Paleogene
Paleogene
The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...

, the Strigiformes radiated
Adaptive radiation
In evolutionary biology, adaptive radiation is the evolution of ecological and phenotypic diversity within a rapidly multiplying lineage. Starting with a recent single ancestor, this process results in the speciation and phenotypic adaptation of an array of species exhibiting different...

 into ecological niche
Ecological niche
In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...

s now mostly filled by other groups of birds. The owls as we know them today, on the other hand, evolved their characteristic morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....

 and adaptation
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....

s during that time, too. By the early Neogene
Neogene
The Neogene is a geologic period and system in the International Commission on Stratigraphy Geologic Timescale starting 23.03 ± 0.05 million years ago and ending 2.588 million years ago...

, the other lineages had been displaced by other bird orders, leaving only barn-owls and typical owls. The latter at that time were usually a fairly generic type of (probably earless) owl similar to today's North American Spotted Owl
Spotted Owl
The Spotted Owl, Strix occidentalis, is a species of true owl. It is a resident species of forests in western North America, where it nests in tree holes, old bird of prey nests, or rock crevices. Nests can be between 13 and 66 yards high and usually contain two eggs...

 or the European Tawny Owl
Tawny Owl
The Tawny Owl or Brown Owl is a stocky, medium-sized owl commonly found in woodlands across much of Eurasia. Its underparts are pale with dark streaks, and the upperparts are either brown or grey. Several of the eleven recognised subspecies have both variants...

; the diversity in size and ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...

 found in typical owls today developed only subsequently.

Around the Paleogene-Neogene boundary (some 25 mya), barn-owls were the dominant group of owls in southern Europe and adjacent Asia at least; the distribution of fossil and present-day owl lineages indicates that their decline is contemporary with the evolution of the different major lineages of typical owls, which for the most part seems to have taken place in Eurasia. In the Americas, there was rather an expansion of immigrant lineages of ancestral typical owls.

The supposed fossil heron
Heron
The herons are long-legged freshwater and coastal birds in the family Ardeidae. There are 64 recognised species in this family. Some are called "egrets" or "bitterns" instead of "heron"....

s "Ardea" perplexa (Middle Miocene of Sansan, France) and "Ardea" lignitum (Late Pliocene of Germany) were more probably owls; the latter was apparently close to the modern genus Bubo. Judging from this, the Late Miocene remains from France described as "Ardea" aureliensis should also be restudied. The Messelasturidae, some of which were initially believed to be basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...

 Strigiformes, are now generally accepted to be diurnal birds of prey showing some convergent evolution
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...

 towards owls. The taxa often united under Strigogyps were formerly placed in part with the owls, specifically the Sophiornithidae; they appear to be Ameghinornithidae instead.

For fossil species and paleosubspecies of extant taxa, see the genus and species articles.
Unresolved and basal forms (all fossil)
  • Berruornis
    Berruornis
    Berruornis orbisantiqui was an early fossil owl or owl-like bird recovered from late Paleocene deposits in the region of Reims in northeastern France. It was about the size of a Eurasian Eagle-owl ....

     (Late Paleocene of France) - basal? Sophornithidae?
  • Strigiformes gen. et ap. indet. (Late Paleocene of Zhylga, Kazakhstan)
  • Palaeoglaux
    Palaeoglaux
    Palaeoglaux is a genus of fossil owl from the Eocene epoch. There are two known species, P. perrierensis from the Upper Eocene of Quercy, France and P. artophoron from the Middle Eocene Messel shales, Germany. The holotype of P. perrierensis is a partial left coracoid in the Collection Université...

     (Middle – Late Eocene of WC Europe) - own family Palaeoglaucidae or Strigidae?
  • Palaeobyas (Late Eocene/Early Oligocene of Quercy, France) - Tytonidae? Sophiornithidae?
  • Palaeotyto (Late Eocene/Early Oligocene of Quercy, France) - Tytonidae? Sophiornithidae?
  • Strigiformes gen. et spp. indet. (Early Oligocene of Wyoming, USA)

Protostrigidae

  • Eostrix
    Eostrix
    Eostrix is an extinct genus of the family Protostrigidae from early Eocene of Wyoming and the London Clay of England. It was erected by Pierce Brodkorb in 1971 to place a fossil species known until that time as Protostrix mimica....

     (Early Eocene of WC USA and England - Middle Eocene of WC USA)
  • Minerva (Middle – Late Eocene of W USA) - formerly Protostrix, includes "Aquila" ferox, "Aquila" lydekkeri, and "Bubo" leptosteus
  • Oligostrix (mid-Oligocene of Saxony, Germany)

Strigidae: Typical owls

  • Aegolius
    Aegolius
    Aegolius is a small genus of owls. Three of the species are restricted to the New World, but th Boreal Owl has a circumpolar range through North America, Eurasia, the Alps and the Rockies.The species are:...

    : saw-whet owls, four species
  • Asio
    Asio
    Asio is a genus of typical owls, or true owls, in family Strigidae. The genus Asio contains the eared owls, which are characterised by feather tufts on the head which have the appearance of ears...

    : eared owls, 6–7 species
  • Athene
    Athene (owl)
    Athene is a genus of owls, containing two to four living species, depending on classification. These birds are small, with brown and white speckles, yellow eyes, and white eyebrows...

    : 2–4 species (depending on whether Speotyto and Heteroglaux are included or not)
  • Bubo
    Horned owl
    The American horned owls and the Old World eagle-owls make up the genus Bubo, at least as traditionally described. This genus, depending on definition, contains about one or two dozen species of typical owls and is found in many parts of the world. Some of the largest living Strigiformes are in...

    : horned owls, eagle-owls and fish-owls; paraphyletic with Nyctea, Ketupa and Scotopelia, some 25 species
  • Ciccaba
    Ciccaba
    Ciccaba is a small genus of typical owls. It contains 4 species:* Mottled Owl, Ciccaba virgata* Black-and-white Owl, Ciccaba nigrolineata* Black-banded Owl, Ciccaba huhula* Rufous-banded Owl, Ciccaba albitarsis...

    : four species
  • Glaucidium: pygmy-owls, about 30–35 species
  • Gymnoglaux: Bare-legged Owl or Cuban Screech-owl
  • Jubula
    Maned Owl
    The Maned Owl is a species of owl in the Strigidae family that is endemic to Africa. It is the only species in genus Jubula....

    : Maned Owl
  • Lophostrix: Crested Owl
  • Megascops: screech-owls, some 20 species
  • Micrathene: Elf Owl
  • Mimizuku: Giant Scops-owl or Mindanao Eagle-owl
  • Ninox
    Ninox
    Ninox is a genus of owls comprising about 20 species found in Asia and Australasia. Many species are known as hawk owls or boobooks...

    : Australasian hawk-owls, some 20 species
  • Nesasio - Fearful Owl
  • Otus
    Scops owl
    Scops owls are Strigidae belong to the genus Otus. Approximately 45 living species are known, but new ones are frequently recognized and unknown ones are still being discovered every few years or so, especially in Indonesia...

    : scops-owls; probably paraphyletic, about 45 species
  • Pseudoscops: Jamaican Owl and possibly Striped Owl
    Striped Owl
    The Striped Owl is a medium-sized owl with large ear tufts and a brownish-white facial disk rimmed with black. Its beak is black, and it has cinnamon-colored eyes. It has shorter, rounder wings than most of its close relatives. The upperparts are cinnamon with fine black vermiculation and heavy...

  • Ptilopsis
    Ptilopsis
    Ptilopsis is a genus of African owls. Its members are:*Northern White-faced Owl Ptilopsis leucotis *Southern White-faced Owl Ptilopsis granti...

    : white-faced owls, two species
  • Pulsatrix
    Pulsatrix
    Pulsatrix is a genus of owl in the Strigidae family. They are called spectacled owls because of their prominent facial pattern.It contains the following species:* Spectacled Owl, Pulsatrix perspicillata...

    : spectacled owls, three species
  • Pyrroglaux: Palau Owl
  • Strix
    Strix (genus)
    Strix is a genus of owls. They belong to the typical owl family Strigidae, one of the two generally accepted living families of owls, with the other being the barn-owls . Common names are earless owls or wood owls though they are not the only owls without ear tufts, and "wood owl" is also used as a...

    : earless owls, about 15 species
  • Surnia: Northern Hawk-owl
  • Uroglaux: Papuan Hawk-owl
  • Xenoglaux: Long-whiskered Owlet

  • Mascarenotus: Mascarene owls, three species; extinct (c.1850)
  • Sceloglaux: Laughing Owl; extinct (1914?)
  • Grallistrix
    Grallistrix
    The stilt-owls are a genus of true owls which contains four species, all of which lived on the Hawaiian Islands but are now extinct....

    : stilt-owls, four species; prehistoric
    Late Quaternary prehistoric birds
    Prehistoric birds are various taxa of birds that became extinct before recorded history, or more precisely, before they could be studied alive by bird scientists...

  • Ornimegalonyx: Caribbean giant owls, 1–2 species; prehistoric
    Late Quaternary prehistoric birds
    Prehistoric birds are various taxa of birds that became extinct before recorded history, or more precisely, before they could be studied alive by bird scientists...


Fossil genera
  • Mioglaux (Late Oligocene? - Early Miocene of WC Europe) - includes "Bubo" poirreiri
  • "Otus/Strix" wintershofensis: fossil
    Fossil
    Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

     (Early/Middle Miocene of Wintershof West, Germany) - may be close to extant genus Ninox
  • Intutula (Early/Middle –? Late Miocene of C Europe) - includes "Strix/Ninox" brevis
  • Alasio (Middle Miocene of Vieux-Collonges, France) - includes "Strix" collongensis

Placement unresolved
  • "Strix" edwardsi: fossil
    Fossil
    Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

     (Middle Miocene)
  • "Asio" pygmaeus: fossil
    Fossil
    Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

     (Early Pliocene of Odessa, Ukraine)
  • Ibiza Owl, Strigidae gen. et sp. indet.: prehistoric
    Late Quaternary prehistoric birds
    Prehistoric birds are various taxa of birds that became extinct before recorded history, or more precisely, before they could be studied alive by bird scientists...


Tytonidae: Barn-owls

  • Genus Tyto
    Tyto
    The genus Tyto includes all barn owls except for the bay owls - that is, the true barn owls, the grass owls and the masked owls collectively making up the subfamily Tytoninae...

    : typical barn-owls, stand up to 1/2 ft tall. Some 15 species and possibly one recently extinct
  • Genus Phodilus
    Bay Owl
    The bay owls are barn owls of the genus Phodilus, subfamily Phodilinae. Most classification schemes recognize two species in this genus: the Oriental Bay Owl and the Congo Bay Owl ....

    : bay-owls, 1–2 extant species and possibly one recently extinct


Fossil genera
  • Nocturnavis (Late Eocene/Early Oligocene) - includes "Bubo" incertus
  • Necrobyas (Late Eocene/Early Oligocene - Late Miocene) - includes "Bubo" arvernensis and Paratyto
  • Selenornis (Late Eocene/Early Oligocene) - includes "Asio" henrici
  • Prosybris (Early Oligocene? - Early Miocene)

Placement unresolved
  • Tytonidae gen. et sp. indet. "TMT 164" (Middle Miocene) - Prosybris?

Africa

Among the Kikuyu of Kenya
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...

 it was believed that owls were harbingers of death. If one saw an owl or heard its hoot, someone was going to die. In general, owls are viewed as harbingers of bad luck, ill health, or death. The belief is widespread even today.

The Americas

In the culture of the Uto-Aztec
Uto-Aztecan languages
Uto-Aztecan or Uto-Aztekan is a Native American language family consisting of over 30 languages. Uto-Aztecan languages are found from the Great Basin of the Western United States , through western, central and southern Mexico Uto-Aztecan or Uto-Aztekan is a Native American language family...

 tribe, the Hopi
Hopi
The Hopi are a federally recognized tribe of indigenous Native American people, who primarily live on the Hopi Reservation in northeastern Arizona. The Hopi area according to the 2000 census has a population of 6,946 people. Their Hopi language is one of the 30 of the Uto-Aztecan language...

, taboos surround owls, which are associated with sorcery and other evils. The Aztec
Aztec
The Aztec people were certain ethnic groups of central Mexico, particularly those groups who spoke the Nahuatl language and who dominated large parts of Mesoamerica in the 14th, 15th and 16th centuries, a period referred to as the late post-classic period in Mesoamerican chronology.Aztec is the...

s and Maya
Maya civilization
The Maya is a Mesoamerican civilization, noted for the only known fully developed written language of the pre-Columbian Americas, as well as for its art, architecture, and mathematical and astronomical systems. Initially established during the Pre-Classic period The Maya is a Mesoamerican...

, along with other Natives of Mesoamerica
Mesoamerica
Mesoamerica is a region and culture area in the Americas, extending approximately from central Mexico to Belize, Guatemala, El Salvador, Honduras, Nicaragua, and Costa Rica, within which a number of pre-Columbian societies flourished before the Spanish colonization of the Americas in the 15th and...

, considered the owl a symbol of death and destruction. In fact, the Aztec god of death, Mictlantecuhtli
Mictlantecuhtli
Mictlantecuhtli , in Aztec mythology, was a god of the dead and the king of Mictlan , the lowest and northernmost section of the underworld. He was one of the principal gods of the Aztecs and was the most prominent of several gods and goddesses of death and the underworld...

, was often depicted with owls. There is an old saying in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 that is still in use: Cuando el tecolote canta, el indio muere ("When the owl cries/sings, the Indian dies"). The Popol Vuh, a Mayan religious text, describes owls as messengers of Xibalba (the Mayan "Place of Fright"). The belief that owls are messengers and harbingers of the dark powers is also found among the Hočągara
Ho-Chunk
The Ho-Chunk, also known as Winnebago, are a tribe of Native Americans, native to what is now Wisconsin and Illinois. There are two federally recognized Ho-Chunk tribes, the Ho-Chunk Nation of Wisconsin and Winnebago Tribe of Nebraska....

 (Winnebago) of Wisconsin. When in earlier days the Hočągara committed the sin of killing enemies while they were within the sanctuary of the chief's lodge, an owl appeared and spoke to them in the voice of a human, saying, "From now on the Hočągara will have no luck." This marked the beginning of the decline of their tribe. An owl appeared to Glory of the Morning
Glory of the Morning
Glory of the Morning was the first woman ever described in the written history of Wisconsin, and the only known female chief of the Hocąk nation...

, the only female chief of the Hočąk nation, and uttered her name. Soon afterwards she died. People often allude to the reputation of owls as bearers of supernatural danger when they tell misbehaving children, "the owls will get you." Also, in the native Cherokee culture, as well as many other Native American cultures, owls are a very bad omen. It is said that if you are outside in the broad day light and owl flies over your head a family member or loved one would die within the coming week.

Hinduism

In Hinduism
Hinduism
Hinduism is the predominant and indigenous religious tradition of the Indian Subcontinent. Hinduism is known to its followers as , amongst many other expressions...

, an owl is the vahana
Vahana
Vāhana denotes the being, typically an animal or mythical entity, a particular deva is said to use as a vehicle. In this capacity, the vāhana is often called the deity's mount. Upon the partnership between the deva and his vāhana is woven much iconography and mythology...

, mount, of Goddess Lakshmi
Lakshmi
Lakshmi or Lakumi is the Hindu goddess of wealth, prosperity , light, wisdom, fortune, fertility, generosity and courage; and the embodiment of beauty, grace and charm. Representations of Lakshmi are also found in Jain monuments...

.

Western culture

The modern West
Western culture
Western culture, sometimes equated with Western civilization or European civilization, refers to cultures of European origin and is used very broadly to refer to a heritage of social norms, ethical values, traditional customs, religious beliefs, political systems, and specific artifacts and...

 generally associates owls with wisdom
Wisdom
Wisdom is a deep understanding and realization of people, things, events or situations, resulting in the ability to apply perceptions, judgements and actions in keeping with this understanding. It often requires control of one's emotional reactions so that universal principles, reason and...

. This link goes back at least as far as Ancient Greece
Ancient Greece
Ancient Greece is a civilization belonging to a period of Greek history that lasted from the Archaic period of the 8th to 6th centuries BC to the end of antiquity. Immediately following this period was the beginning of the Early Middle Ages and the Byzantine era. Included in Ancient Greece is the...

, where Athens
Athens
Athens , is the capital and largest city of Greece. Athens dominates the Attica region and is one of the world's oldest cities, as its recorded history spans around 3,400 years. Classical Athens was a powerful city-state...

, noted for art and scholarship, and Athena
Athena
In Greek mythology, Athena, Athenê, or Athene , also referred to as Pallas Athena/Athene , is the goddess of wisdom, courage, inspiration, civilization, warfare, strength, strategy, the arts, crafts, justice, and skill. Minerva, Athena's Roman incarnation, embodies similar attributes. Athena is...

, Athens' patron goddess and the goddess of wisdom, had the owl as a symbol. Marija Gimbutas
Marija Gimbutas
Marija Gimbutas , was a Lithuanian-American archeologist known for her research into the Neolithic and Bronze Age cultures of "Old Europe", a term she introduced. Her works published between 1946 and 1971 introduced new views by combining traditional spadework with linguistics and mythological...

 traces veneration of the owl as a goddess, among other birds, to the culture of Old Europe, long pre-dating Indo-European
Indo-European
Indo-European may refer to:* Indo-European languages** Aryan race, a 19th century and early 20th century term for those peoples who are the native speakers of Indo-European languages...

 cultures.

T. F. Thiselton-Dyer in his Folk-lore of Shakespeare says that "from the earliest period it has been considered a bird of ill-omen, and Pliny
Pliny the Elder
Gaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...

 tells us how, on one occasion, even Rome
Rome
Rome is the capital of Italy and the country's largest and most populated city and comune, with over 2.7 million residents in . The city is located in the central-western portion of the Italian Peninsula, on the Tiber River within the Lazio region of Italy.Rome's history spans two and a half...

 itself underwent a lustration, because one of them strayed into the Capitol. He represents it also as a funereal bird, a monster of the night, the very abomination of human kind. Virgil
Virgil
Publius Vergilius Maro, usually called Virgil or Vergil in English , was an ancient Roman poet of the Augustan period. He is known for three major works of Latin literature, the Eclogues , the Georgics, and the epic Aeneid...

 describes its death-howl from the top of the temple by night, a circumstance introduced as a precursor of Dido's death. Ovid
Ovid
Publius Ovidius Naso , known as Ovid in the English-speaking world, was a Roman poet who is best known as the author of the three major collections of erotic poetry: Heroides, Amores, and Ars Amatoria...

, too, constantly speaks of this bird's presence as an evil omen; and indeed the same notions respecting it may be found among the writings of most of the ancient poets."

In France, where owls are divided into eared owls (hiboux) and earless owls (chouettes), the former are seen as symbols of wisdom while the latter are assigned the grimmer meaning.

Use as rodent control

Encouraging natural predators to control rodent population is a natural form of pest control, along with excluding food sources for rodents. Placing a new box for owls on a property can help control rodent populations (one family of hungry barn owls can consume more than 3,000 rodents in a nesting season) while maintaining the naturally balanced food chain.

Owl conservation issues

All owls are listed in Appendix II of the international CITES treaty (the Convention on Illegal Trade in Endangered Species of Wild Fauna and Flora). Although owls have long been hunted, a 2008 news story from Malaysia indicates that the magnitude of owl poaching
Poaching
Poaching is the illegal taking of wild plants or animals contrary to local and international conservation and wildlife management laws. Violations of hunting laws and regulations are normally punishable by law and, collectively, such violations are known as poaching.It may be illegal and in...

 may be on the rise. In November 2008, TRAFFIC
Traffic
Traffic on roads may consist of pedestrians, ridden or herded animals, vehicles, streetcars and other conveyances, either singly or together, while using the public way for purposes of travel...

 reported the seizure of 900 plucked and "oven-ready" owls in Peninsular Malaysia. Said Chris Shepherd, Senior Programme Officer for TRAFFIC's Southeast Asia office, "This is the first time we know of where 'ready-prepared' owls have been seized in Malaysia, and it may mark the start of a new trend in wild meat from the region. We will be monitoring developments closely." Traffic commended the Department of Wildlife and National Parks in Malaysia for the raid that exposed the huge haul of owls. Included in the seizure were dead and plucked Barn Owls, Spotted Wood Owls, Crested Serpent Eagles, Barred Eagles, and Brown Wood Owls, as well as 7,000 live lizards.

External links


Eurasia
North America
Oceania
  • iprimus info. re Australian owls and frogmouth
    Frogmouth
    The frogmouths are a group of nocturnal birds related to the nightjars. They are found from India across southern Asia to Australia.They are named for their large flattened hooked bills and huge frog-like gape, which they use to capture insects. Their flight is weak.They rest horizontally on...

    s
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK