68-413: Strigidae Tytonidae Ogygoptyngidae ( fossil ) Palaeoglaucidae ( fossil ) Protostrigidae ( fossil ) Sophiornithidae ( fossil ) Strigidae sensu Sibley & Ahlquist Owls are birds from the order Strigiformes ( / ˈ s t r ɪ dʒ ə f ɔːr m iː z / ), which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance,
136-478: A facial ruff, which creates an anterior-facing, concave wall that cups the sound into the ear structure. This facial ruff is poorly defined in some species, and prominent, 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 minimizes sound reflection away from the face. The shape of the facial disk is adjustable at will to focus sounds more effectively. The prominences above
204-453: A few centimetres of their eyes. Caught prey can be felt by owls with the use of filoplumes —hairlike feathers on the beak and feet that act as "feelers". Their far vision, particularly in low light, is exceptionally good. Owls can rotate their heads and necks as much as 270°. Owls have 14 neck vertebrae — humans have only seven — and their vertebral circulatory systems are adapted to allow them to rotate their heads without cutting off blood to
272-506: A few species specialize in hunting fish . They are found in all regions of the Earth except the polar ice caps and some remote islands. A group of owls is called a "parliament". Owls possess large, forward-facing eyes and ear-holes, a hawk -like beak , a flat face, and usually a conspicuous circle of feathers, a facial disc , around each eye. The feathers making up this disc can be adjusted to sharply focus sounds from varying distances onto
340-462: A force over 130 N to release prey in its talons. An owl's talons, like those of most birds of prey, can seem massive in comparison to the body size outside of flight. The Tasmanian masked owl has some of the proportionally longest talons of any bird of prey; they appear enormous in comparison to the body when fully extended to grasp prey. An owl's claws are sharp and curved. The family Tytonidae has inner and central toes of about equal length, while
408-419: A great horned owl's head are commonly mistaken as its ears. This is not the case; they are merely feather tufts. The ears are on the sides of the head in the usual location (in two different locations as described above). While the auditory and visual capabilities of the owl allow it to locate and pursue its prey, the talons and beak of the owl do the final work. The owl kills its prey using these talons to crush
476-470: A hundredth the size of the largest, the Eurasian eagle-owl and Blakiston's fish owl , owls generally share an extremely similar body plan. They tend to have large heads, short tails, cryptic plumage , and round facial discs around the eyes. The family is generally arboreal (with a few exceptions like the burrowing owl ) and obtain their food on the wing. The wings are large, broad, rounded, and long. As
544-401: A large, broad head, binocular vision , binaural hearing , sharp talons , and feathers adapted for silent flight. Exceptions include the diurnal northern hawk-owl and the gregarious burrowing owl . Owls are divided into two families : the true (or typical) owl family, Strigidae, and the barn owl family, Tytonidae. Owls hunt mostly small mammals , insects , and other birds, although
612-619: A male's sexual advances, smaller male owls that have the ability to escape unreceptive females are more likely to have been selected. If the character is stable, there can be different optimums for both sexes. Selection operates on both sexes at the same time; therefore it is necessary to explain not only why one of the sexes is relatively bigger, but also why the other sex is smaller. If owls are still evolving toward smaller bodies and longer wing chords, according to V. Geodakyan's Evolutionary Theory of Sex, males should be more advanced on these characters. Males are viewed as an evolutionary vanguard of
680-557: A population, and sexual dimorphism on the character, as an evolutionary "distance" between the sexes. "Phylogenetic rule of sexual dimorphism" states that if there exists a sexual dimorphism on any character, then the evolution of this trait goes from the female form toward the male one. All owls are carnivorous birds of prey and live on diets of insects, small rodents and lagomorphs. 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
748-525: 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 strepsirrhine primates 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 heads to view their surroundings. Owls' heads are capable of swiveling through an angle of roughly 270°, easily enabling them to see behind them without relocating
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#1732772415222816-412: A strong advantage over prey alert to the slightest sound in the night. A silent, slow flight is not as necessary for diurnal and crepuscular owls given that prey can usually see an owl approaching. Owls' feathers are generally larger than the average birds' feathers, have fewer radiates, longer pennulum, and achieve smooth edges with different rachis structures. Serrated edges along the owl's remiges bring
884-520: A very different way (such as the terrestrial Sophiornithidae ). The Paleocene genera Berruornis and Ogygoptynx show that owls were already present as a distinct lineage some 60–57 million years ago (Mya), hence, possibly also some 5 million years earlier, at the extinction of the non-avian dinosaurs . This makes them one of the oldest known groups of non- Galloanserae landbirds. The supposed " Cretaceous owls" Bradycneme and Heptasteornis are apparently non- avialan maniraptors . During
952-412: Is a physical difference between males and females of a species. Female owls are typically larger than the males. The degree of size dimorphism varies across multiple populations and species, and is measured through various traits, such as wing span and body mass. One theory suggests that selection has led males to be smaller because it allows them to be efficient foragers . The ability to obtain more food
1020-445: Is able to determine the direction from which the sound is coming by the minute difference in time that it takes for the sound waves to penetrate the left and right ears. The owl turns its head until the sound reaches both ears at the same time, at which point it is directly facing the source of the sound. This time difference between ears is about 30 microseconds. Behind the ear openings are modified, dense feathers, densely packed to form
1088-492: Is advantageous during breeding season. In some species, female owls stay at their nest with their eggs while it is the responsibility of the male to bring back food to the nest. If food is scarce, the male first feeds himself before feeding the female. Small birds, which are agile, are an important source of food for owls. Male burrowing owls have been observed to have longer wing chords than females, despite being smaller than females. Furthermore, owls have been observed to be roughly
1156-1344: Is based on the results of the study by Salter and collaborators published in 2020. The subfamilies are those defined by Edward Dickinson and James Van Remsen Jr. in 2013. A genetic study published in 2021 suggested that the genus Scotopelia may be embedded within Ketupa . Ninox – 36 species: hawk-owls and boobooks Uroglaux – Papuan hawk-owl (position uncertain) Aegolius – 5 species Athene – 9 species Glaucidium – 29 species: pygmy owls Surnia – northern hawk-owl Margarobyas – bare-legged owl (position uncertain) Taenioptynx – 2 species Micrathene – elf owl Xenoglaux – long-whiskered owlet Otus – 58 species: scops owls Asio – 9 species in total Ptilopsis – 2 species Jubula – maned owl (position uncertain) Bubo – 10 species: eagle-owls, horned-owls and snowy owl Ketupa – 12 species: fish owls and eagle-owls Scotopelia – 3 species: fishing owls Megascops – 25 species: screech owls Gymnasio – Puerto Rican owl Psiloscops – flammulated owl Strix – 22 species: earless owls Lophostrix – crested owl Pulsatrix – 3 species The 235 extant or recently extinct species are assigned to 23 genera : The fossil database for Strigiformes
1224-467: Is declining at a more rapid pace. This invasion by barred owls occurred about 50 years ago in the Pacific Northwest , and despite their low numbers, they are considered an invasive species because of the harm done to native spotted owls. In this competition for resources , hunting locations and general niches, the barred owl is pushing the spotted owl to local extinction . It is thought that
1292-1064: Is disputed. See below cladogram : Cathartiformes (New World vultures) [REDACTED] Accipitriformes ( hawks and relatives) [REDACTED] Strigiformes (owls) [REDACTED] Coliiformes (mouse birds) Leptosomiformes (cuckoo roller) Trogoniformes (trogons and quetzals) [REDACTED] Bucerotiformes ( hornbills and relatives) Coraciiformes ( kingfishers and relatives) [REDACTED] Piciformes ( woodpeckers and relatives) Cariamiformes (seriemas) [REDACTED] Falconiformes (falcons) [REDACTED] Psittaciformes (parrots) [REDACTED] Passeriformes (passerines) [REDACTED] Cladogram of Telluraves relationships based on Braun & Kimball (2021) Some 220 to 225 extant species of owls are known, subdivided into two families: 1. true owls or typical owls family ( Strigidae ) and 2. barn-owls family ( Tytonidae ). Some entirely extinct families have also been erected based on fossil remains; these differ much from modern owls in being less specialized or specialized in
1360-542: Is highly diverse and shows an origin from ~60MYA into the Pleistocene. The maximum age range for the Strigiformes clade extends to 68.6MYA. Placement unresolved: The supposed fossil heron "Ardea" lignitum (Late Pliocene of Germany) was apparently a strigid owl, possibly close to Bubo . The Early–Middle Eocene genus Palaeoglaux from west-central Europe is sometimes placed here, but given its age, it
1428-441: Is occurring in these two families, there is a concern with the barred owls encroaching on the spotted owl's North American habitats, causing a decline of the spotted owl. As noted above, these species prefer mature forests which, due to deforestation, are at limited supply and take a long time to reestablish after deforestation has occurred. Because the northern spotted owl shares its territories and competes with other species, it
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#17327724152221496-498: Is the case with most birds of prey , in many owl species females are larger than males. Because of their nocturnal habits, they tend not to exhibit sexual dimorphism in their plumage. Specialized feathers and wing shape suppress the noise produced by flying, both taking off, flapping and gliding. This silent flight allows owls to hunt without being heard by their prey. Owls possess three physical attributes that are thought to contribute to their silent flight capability. First, on
1564-622: Is the more common number. In at least one species, female owls do not mate with the same male for a lifetime. Female burrowing owls commonly travel and find other mates, while the male stays in his territory and mates with other females. Recent phylogenetic studies place owls within the clade Telluraves , most closely related to the Accipitrimorphae and the Coraciimorphae , although the exact placement within Telluraves
1632-426: 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 the owl's field of vision to be clear, as well as directing sound into the ears without deflecting sound waves away from the face. The coloration of the owl's plumage plays a key role in its ability to sit still and blend into
1700-546: The Paleogene , the Strigiformes radiated into ecological niches now mostly filled by other groups of birds. The owls as known today, though, evolved their characteristic morphology and adaptations during that time, too. By the early Neogene , the other lineages had been displaced by other bird orders, leaving only barn owls and typical owls. The latter at that time was usually a fairly generic type of (probably earless) owl similar to today's North American spotted owl or
1768-446: The spotted owl and the barred owl (both of which are true owls) . This competition is related to deforestation , and therefore a reduction in niche quantity and quality. This deforestation is more specifically the result of overlogging and forest fires . These two species of owl are known to traditionally live in mature forests of old and tall trees, which at this point in time are mostly limited to public lands . As niche overlap
1836-653: The uropygial gland , informally the "preen" or "oil" gland, as most birds do, to spread oils across their plumage through preening. This makes them highly vulnerable to heavy rain when they are unable to hunt. Historically, they would switch to hunting indoors in wet weather, using barns and other agricultural buildings, but the decline in the numbers of these structures in the 20th and 21st centuries has reduced such opportunities. The lack of waterproofing means that barn owls are also susceptible to drowning, in drinking troughs and other structures with smooth sides. The Barn Owl Trust provides advice on how this can be mitigated, by
1904-562: The European tawny owl ; the diversity in size and ecology 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 true owls, which for
1972-430: The age of owls. The relative ages of the feathers are differentiated by the intensity of fluorescence that they emit when the primaries and secondaries are exposed to black light . This method helps to detect the subtle differences between third and fourth generation feathers, whereas looking at wear and color makes age determination difficult. It has been noted that there is some competition for niche space between
2040-409: The brain . Specifically, the foramina in their vertebrae through which the vertebral arteries pass are about 10 times the diameter of the artery, instead of about the same size as the artery, as is the case in humans; the vertebral arteries enter the cervical vertebrae higher than in other birds, giving the vessels some slack, and the carotid arteries unite in a very large anastomosis or junction,
2108-581: The brain. Several owl species also have fluorescent pigments called porphyrins under their wings. A large group of pigments defined by nitrogen-containing pyrole rings, including chlorophyll and heme (in animal blood), make up the porphyrins. Other bird species will use porphyrins to pigment eggshells in the oviduct. Owl species, however, use porphyrins as a pigment in their plumage. Porphyrins are most prevalent in new feathers and are easily destroyed by sunlight. Porphyrin pigments in feathers fluoresce under UV light, allowing biologists to more accurately classify
Owl - Misplaced Pages Continue
2176-450: The deciduous woodland it prefers for its habitat. Likewise, the mottled wood owl ( Strix ocellata ) displays shades of brown, tan, and black, making the owl nearly invisible in the surrounding trees, especially from behind. Usually, the only tell-tale sign of a perched owl is its vocalizations or its vividly colored eyes. Most owls are nocturnal , actively hunting their prey in darkness. Several types of owls are crepuscular —active during
2244-414: The ears. Hearing in owls is highly sensitive and the ears are asymmetrical allowing the owl to localise a sound in multiple directions. Owls can pinpoint the position of prey, such as a squeaking mouse, by computing when the sound from the object reaches the owl's ears. If the sound reaches the left ear first, the mouse must be to the left of the owl. The owl's brain will then direct the head to directly face
2312-423: The environment, making it nearly invisible to prey. Owls tend to mimic the coloration and sometimes the texture patterns of their surroundings, the barn owl being an exception. The snowy owl ( Bubo scandiacus ) appears nearly bleach-white in color with a few flecks of black, mimicking their snowy surroundings perfectly, while the speckled brown plumage of the tawny owl ( Strix aluco ) allows it to lie in wait among
2380-399: The family Strigidae has an inner toe that is distinctly shorter than the central one. These different morphologies allow efficiency in capturing prey specific to the different environments they inhabit. The beak of the owl is short, curved, and downward-facing, and typically hooked at the tip for gripping and tearing its prey. Once prey is captured, the scissor motion of the top and lower bill
2448-539: The family Strigidae was divided into two sister clades and some of the traditional genera were paraphyletic . The placement of three monotypic genera remained uncertain due to the degraded nature of the available DNA. Based on these results Frank Gill , Pamela Rasmussen and David Donsker updated the online list of world birds that they maintain on behalf of the International Ornithological Committee (IOC). The cladogram below
2516-746: The feathers of their prey to signal their breeding status to members within the same species. Some species of owl are migratory. One such species, the northern saw-whet owl , migrates south even when food and resources are ample in the north. Some owls have a higher survival rate and are more likely to reproduce in a habitat that contains a mixture of old growth forests and other vegetation types. Old growth forests provide ample dark areas for owls to hide from predators Like many organisms, spotted owls rely on forest fires to create their habitat and provide areas for foraging. Unfortunately, climate change and intentional fire suppression have altered natural fire habits. Owls avoid badly burned areas but they benefit from
2584-415: The flapping of the wing down to a nearly silent mechanism. The serrations are more likely reducing aerodynamic disturbances, rather than simply reducing noise. The surface of the flight feathers is covered with a velvety structure that 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
2652-429: The genus Glaucidium and the northern hawk-owl have eye patches on the backs of their heads, apparently to convince other birds they are being watched at all times. Numerous nocturnal species have ear-tufts, feathers on the sides of the head that are thought to have a camouflage function, breaking up the outline of a roosting bird. The feathers of the facial disc are arranged in order to increase sound delivered to
2720-558: The ground in brushy areas typically of cedar forests. These owls eat mice, and perch in trees at eye level. Their main predators are barred owls and great horned owls. The family Strigidae was introduced by the English zoologist William Elford Leach in a guide to the contents of the British Museum published in 1819. A molecular phylogenetic study of the owls by Jessie Salter and collaborators published in 2020 found that
2788-467: The inconspicuous locations they adopt are an effort to avoid predators and mobbing by small birds. Owls, such as the eagle-owl , will use visual signaling in intraspecific communication (communication within the species), both in territorial habits and parent-offspring interactions. Some researchers believe owls can employ various visual signals in other situations involving intraspecific interaction . Experimental evidence suggests that owl feces and
Owl - Misplaced Pages Continue
2856-444: The indigestible parts of their prey (such as bones, scales, and fur) in the form of pellets . 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. Owl eggs typically have a white color and an almost spherical shape, and range in number from a few to a dozen, depending on species and the particular season; for most, three or four
2924-415: The installation of floats. Eyesight is a particular characteristic of the owl that aids in nocturnal prey capture. 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 skulls. An apparent consequence of the evolution of an absolutely large eye in
2992-468: 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 its nocturnal eyesight to be far superior to that of its average prey. Owls exhibit specialized hearing functions and ear shapes that also aid in hunting. They are noted for asymmetrical ear placements on
3060-439: The largest of any bird's, preventing blood supply from being cut off while they rotate their necks. Other anastomoses between the carotid and vertebral arteries support this effect. The smallest owl—weighing as little as 31 g ( 1 + 3 ⁄ 32 oz) and measuring some 13.5 cm ( 5 + 1 ⁄ 4 in)—is the elf owl ( Micrathene whitneyi ). Around the same diminutive length, although slightly heavier, are
3128-413: 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 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
3196-477: The leading edge of the wing, there is a comb of stiff feathers. Second, the trailing edge of the wing contains a flexible fringe. Finally, owls have downy material distributed on the tops of their wings that creates a compliant but rough surface (similar to that of a soft carpet). All these factors result in significant aerodynamic noise reductions. The toes and tarsi are feathered in some species, and more so in species at higher latitudes. Numerous species of owls in
3264-740: The lesser known long-whiskered owlet ( Xenoglaux loweryi ) and Tamaulipas pygmy owl ( Glaucidium sanchezi ). The largest owls are two similarly sized eagle owls ; the Eurasian eagle-owl ( Bubo bubo ) and Blakiston's fish owl ( Bubo blakistoni ). The largest females of these species are 71 cm (28 in) long, have a 190 cm (75 in) wing span, and weigh 4.2 kg ( 9 + 1 ⁄ 4 lb). Different species of owls produce different sounds; this distribution 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 distinguishing species. As noted above, their facial discs help owls to funnel
3332-450: The mosaics of heterogeneous habitats created by fires. This is not to say that all fires are good for owls. Owls only thrive when fires are not of high severity and not large stand-replacing (high-severity fires that burn most of the vegetation) which create large canopy gaps that are not adequate for owls. Avian malaria or Plasmodium relictum affects owls and specifically, 44% of northern and Californian spotted owls harbor 17 strains of
3400-930: The most part seems to have taken place in Eurasia. In the Americas, rather, an expansion of immigrant lineages of ancestral typical owls occurred. The supposed fossil herons "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 Strigiformes, are now generally accepted to be diurnal birds of prey showing some convergent evolution toward owls. The taxa often united under Strigogyps were formerly placed in part with
3468-506: The mouse. In addition to hearing, owls have massive eyes relative to their body size. Contrary to popular belief, however, owls cannot see well in extreme dark and are able to see well in the day. Owls are also able to rotate their heads by as much as 270 degrees in either direction without damaging the blood vessels in their necks and heads, and without disrupting blood flow to their brains. Researchers have found four major biological adaptations that allow for this unique capability. First, in
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#17327724152223536-482: The neck higher up than it does in other birds. Instead of going in at the 14th cervical vertebrae, it enters in at the 12th cervical vertebrae. Finally, the small vessel connection between the carotid and the vertebral arteries allow the exchanging of blood between two blood vessels. These cross connections allow for uninterrupted blood flow to the brain. This means that even if one route is blocked during extreme head rotations, another route can continue blood circulation to
3604-460: The neck there is a major artery, called the vertebral artery, that feeds the brain. This artery passes through bony holes in the vertebra. These bony holes are ten times larger in diameter than the artery that passes through them (extra space in the transverse foramina) which creates air pockets that allow for more movement of the artery when twisted. 12 of the 14 cervical vertebrae in the owl's neck have this adaptation. This vertebral artery also enters
3672-485: The nest. Therefore, females may have a larger mass to allow them to go for a longer period of time without starving. For example, one hypothesized sexual role is that larger females are more capable of dismembering prey and feeding it to their young, hence female owls are larger than their male counterparts. A different theory suggests that the size difference between male and females is due to sexual selection: since large females can choose their mate and may violently reject
3740-452: The owl's usual prey and also within the owl's own best hearing range. This optimizes the owl's ability to silently fly to capture prey without the prey hearing the owl first as it flies, and to hear any noise the prey makes. It also allows the owl to monitor the sound output from its flight pattern. The disadvantage of such feather adaptations for barn owls is that their feathers are not waterproof. The adaptations mean that barn owls do not use
3808-478: The owls' asymmetrically placed ear cavities. Most birds of prey have 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. Owls have binocular vision , but they must rotate their entire heads to change the focus of their view because, like most birds, their eyes are fixed in their sockets. Owls are farsighted and cannot clearly see anything nearer than
3876-499: 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. For a full list of extant and recently extinct owls, see the article List of owl species . True owl some 25, see text Striginae sensu Sibley & Ahlquist The true owls or typical owls ( family Strigidae ) are one of
3944-410: The parasite. As mentioned in the niche competition section above, spotted owls and barred owls are in competition so their niche overlap may be resulting in the plasmodium parasite having more hosts in a concentrated area but this is not certain. The main predators of owls are other species of owls. An example of this occurs with the northern saw-whet owl that lives in the northern U.S. and lives low to
4012-448: The rapid decrease in population size of spotted owls will cause a trophic cascade , since the spotted owls help provide a healthy ecosystem . Owls are generally nocturnal and/or crepuscular and spend much of the day roosting . They are often misperceived as ‘tame’ since they allow humans to approach quite closely before taking flight, but in reality they are attempting to avoid detection through stillness. Their cryptic plumage and
4080-483: The remains of prey can act as visual signals. This new type of signaling behavior could potentially indicate the owls' current reproductive state to intruders, including other territorial owls or non-breeding floaters. Feces are an ideal material for marking due to its minimal energetic costs, and can also continue to indicate territorial boundaries even when occupied in activities other than territorial defense. Preliminary evidence also suggests that owls will use feces and
4148-425: The same size as their prey. This has also been observed in other predatory birds, which suggests that owls with smaller bodies and long wing chords have been selected for because of the increased agility and speed that allows them to catch their prey. Another popular theory suggests that females have not been selected to be smaller like male owls because of their sexual roles. In many species, female owls may not leave
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#17327724152224216-414: The skull and knead the body. The crushing power of an owl's talons varies according to prey size and type, and by the size of the owl. The burrowing owl ( Athene cunicularia ), a small, partly insectivorous owl, has a release force of only 5 N. The larger barn owl ( Tyto alba ) needs a force of 30 N to release its prey, and one of the largest owls, the great horned owl ( Bubo virginianus ), needs
4284-440: The skull in some genera. Owls can have either internal or external ears, both of which are asymmetrical. Asymmetry has not been reported to extend to the middle or internal ear of the owl. Asymmetrical ear placement on the skull allows the owl to pinpoint the location of its prey. This is especially true for strictly nocturnal species such as the barn owls Tyto or Tengmalm's owl. With ears set at different places on its skull, an owl
4352-463: The sound of prey to their ears. In many species, these discs are placed asymmetrically, for better directional location. Owl plumage is generally cryptic , although several species have facial and head markings, including face masks, ear tufts , and brightly colored irises . 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. Sexual dimorphism
4420-418: The torso. This ability keeps bodily movement at a minimum, 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 among all avian groups, which gives them some of the largest binocular fields of vision. Owls are farsighted and cannot focus on objects within a few centimetres of their eyes. These mechanisms are only able to function due to
4488-503: The twilight hours of dawn and dusk; one example is the pygmy owl ( Glaucidium ). A few owls are active during the day, also; examples are the burrowing owl ( Speotyto cunicularia ) and the short-eared owl ( 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
4556-415: The two generally accepted families of owls , the other being the barn owls (Tytonidae). This large family comprises 230 living or recently extinct species in 24 genera . The Strigidae owls have a cosmopolitan distribution and are found on every continent except Antarctica . While typical owls (hereafter referred to simply as owls) vary greatly in size, with the smallest species, the elf owl , being
4624-405: 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. 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
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