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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. The feathers making up this disc can be adjusted by the bird to alter the focal length of this sound collector, enabling the bird to focus at different distances and allowing it to locate prey by sound alone under snow, grass, and plant cover. Other bird species, such as harriers, have less prominent facial discs. In harriers, the related term facial ruff refers to feathers around the neck that are raised in response to noise, essentially enlarging the facial disc and improving hearing. The barn owl has the most visually prominent facial disc, measuring about 110 mm (Simmons), while the great grey owl has the largest disc of any bird. Due to shared inner ear anatomy with barn owls, it is theorized tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tyto Alba Close Up
''Tyto'' is a genus of owls in the family Tytonidae. Depending on the species and the locality, common names include barn owl, common barn owl, grass owl, sooty owl, masked owl, field owl or simply owl. It is the most Cosmopolitan distribution, widely distributed genus of owls in the world and one of the most widespread of all genuses of birds, living almost everywhere except for Polar region, polar and desert regions, Asia north of the Himalayas, some List of islands of Indonesia, Indonesian islands and some Pacific Islands. The genus comprises three widespread continental species and many island species including the extinct island species. The widespread species comprise: western barn owl of Europe, western Asia and Africa, the eastern barn owl of Southeast Asia and Australasia, and the American barn owl of the Americas. However, some taxonomic authorities classify barn owls differently, and unify all continental barn owls in to one species. Further research is needed clarify ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horned Owl
The Americas, American (North and South America) horned owls and the Old World eagle-owls make up the genus ''Bubo'', at least as traditionally described. The genus name ''Bubo'' is Latin for owl. This genus contains 10 species that are found in many parts of the world. Some of the largest living Strigiformes are in ''Bubo''. Traditionally, only owls with ear-tufts were included in this genus, but that is no longer the case. Taxonomy The genus ''Bubo'' was introduced in 1805 by the French zoologist André Marie Constant Duméril, André Duméril for the horned owls. The type species is the Eurasian eagle-owl. The word ''bubo'' is Latin for the Eurasian eagle owl and was used as the specific epithet for the species by Carl Linnaeus in 1758. A molecular phylogenetic study published in 2020 found that species in the genera ''Scotopelia'' and ''Ketupa'' were embedded within the clade containing members of the genus ''Bubo'' making the genus ''Bubo'' paraphyletic. To create monop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bird Anatomy
Bird anatomy, or the physiological structure of birds' bodies, shows many unique adaptations, mostly aiding flight. Birds have a light skeletal system and light but powerful musculature which, along with circulatory and respiratory systems capable of very high metabolic rates and oxygen supply, permit the bird to fly. The development of a beak has led to evolution of a specially adapted digestive system. Skeletal system Birds have many bones that are hollow ( pneumatized) with criss-crossing struts or trusses for structural strength. The number of hollow bones varies among species, though large gliding and soaring birds tend to have the most. Respiratory air sacs often form air pockets within the semi-hollow bones of the bird's skeleton. The bones of diving birds are often less hollow than those of non-diving species. Penguins, loons, puffins, and kiwis are without pneumatized bones entirely. Flightless birds, such as ostriches and emus, have pneumatized femurs and, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound Localization In Owls
Most owls are nocturnal or crepuscular birds of prey. Because they hunt at night, they must rely on non-visual senses. Experiments by Roger Payne have shown that owls are sensitive to the sounds made by their prey, not the heat or the smell. In fact, the sound cues are both necessary and sufficient for localization of mice from a distant location where they are perched. For this to work, the owls must be able to accurately localize both the azimuth and the elevation of the sound source. Introduction to sound localization Owls are very adept nocturnal predators, hunting prey that includes small mammals, reptiles, and insects. They are able to rotate their head up to 270 degrees, lock onto prey, and launch a silent attack. Owls lock onto prey by using sound localization. Sound localization is an animal’s ability to identify the origin of a sound in distance and direction. Several owl species have ears that are asymmetrical in size and location, which enhances this ability. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vestigiality
Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on comparison with homology (biology), homologous features in related species. The emergence of vestigiality occurs by normal evolutionary processes, typically by loss of function of a feature that is no longer subject to Directional selection, positive Evolutionary pressure, selection pressures when it loses its value in a changing environment. The feature may be Negative selection (natural selection), selected against more urgently when its function becomes definitively harmful, but if the lack of the feature provides no advantage, and its presence provides no disadvantage, the feature may not be phased out by natural selection and persist across species. Examples of vestigial structures (also called degenerate, atrophied, or rudimentary orga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Montagu's Harrier
Montagu's harrier (''Circus pygargus'') is a migratory bird of prey of the harrier family. Its common name commemorates the British naturalist George Montagu. Taxonomy The first formal description of Montagu's harrier was by the Swedish naturalist Carl Linnaeus in 1758, in the tenth edition of his ''Systema Naturae'', under the binomial name ''Falco pygargus''. The genus ''Circus'' was introduced by the French naturalist Bernard Germain de Lacépède in 1799. The genus name is derived from Ancient Greek. ''Circus'' is from ''kirkos'', meaning "circle", referring to a bird of prey named for its circling flight (probably the hen harrier), and ''pygargus'' is Modern Latin derived from the Greek ''pugargos'', from ''puge'', meaning "rump", and ''argos'', meaning "shining white". The species name was formerly used for the hen harrier before Montagu's was identified as a different species. Identification Plumage Sexual dimorphism is particularly apparent in the plumage of thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hen Harrier
The hen harrier (''Circus cyaneus'') is a bird of prey. It breeds in Palearctic, Eurasia. The term "hen harrier" refers to its former habit of preying on free-ranging fowl. It bird migration, migrates to more southerly areas in winter. Eurasian birds move to southern Europe and southern temperate Asia. In the mildest regions, such as France and Great Britain, hen harriers may be present all year, but the higher ground is largely deserted in winter. The northern harrier was formerly considered to be a subspecies of the hen harrier. Taxonomy In 1758 the English naturalist George Edwards (naturalist), George Edwards included an illustration and a description of the hen harrier in the first volume of his ''Gleanings of Natural History''. He used the English name "The blue hawk". Edwards based his hand-coloured etching on a bird that had been shot near London. When in 1766 the Swedish naturalist Carl Linnaeus updated his ''Systema Naturae'' for the 12th edition of Systema Naturae, tw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is Cladogram#Homoplasies, homoplasy. The recurrent evolution of flight is a classic example, as flying pterygota, insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are ''analogous'', whereas ''homology (biology), homologous'' structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence is divergent evolution, where related species evolve different trai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Auricle (anatomy)
The auricle or auricula is the visible part of the ear that is outside the head. It is also called the pinna (Latin for 'wing' or ' fin', : pinnae), a term that is used more in zoology. Structure The diagram shows the shape and location of most of these components: * ''antihelix'' forms a 'Y' shape where the upper parts are: ** ''Superior crus'' (to the left of the ''fossa triangularis'' in the diagram) ** ''Inferior crus'' (to the right of the ''fossa triangularis'' in the diagram) * ''Antitragus'' is below the ''tragus'' * ''Aperture'' is the entrance to the ear canal * ''Auricular sulcus'' is the depression behind the ear next to the head * ''Concha'' is the hollow next to the ear canal * Conchal angle is the angle that the back of the ''concha'' makes with the side of the head * ''Crus'' of the helix is just above the ''tragus'' * ''Cymba conchae'' is the narrowest end of the ''concha'' * External auditory meatus is the ear canal * ''Fossa triangularis'' is the depression ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snowy Owl
The snowy owl (''Bubo scandiacus''), also known as the polar owl, the white owl and the Arctic owl, is a large, white owl of the true owl family. Snowy owls are native to the Arctic regions of both North America and the Palearctic, breeding mostly on the tundra. It has a number of unique adaptations to its habitat and lifestyle, which are quite distinct from other extant owls. One of the largest species of owl, it is the only owl with mainly white plumage. Males tend to be a purer white overall while females tend to have more extensive flecks of dark brown. Juvenile male snowy owls have dark markings and may appear similar to females until maturity, at which point they typically turn whiter. The composition of brown markings about the wing, although not foolproof, is the most reliable technique for aging and sexing individual snowy owls. Most owls sleep during the day and hunt at night, but the snowy owl is often active during the day, especially in the summertime. The snowy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strigidae
The true owls or typical owls (family (biology), family Strigidae) are one of the two generally accepted families of owls, the other being the barn owls and bay owls (Tytonidae). This large family comprises 230 living or recently extinct species in 24 genus, genera. The Strigidae owls have a cosmopolitan distribution and are found on every continent except Antarctica. Morphology While typical owls (hereafter referred to simply as owls) vary greatly in size, with the smallest species, the elf owl, being a hundredth the size of the largest, the Eurasian eagle-owl and Blakiston's fish owl, owls generally share an extremely similar body plan.Marks, J. S.; Cannings, R.J. and Mikkola, H. (1999). "Family Strigidae (Typical Owls)". ''In'' del Hoyo, J.; Elliot, A. & Sargatal, J. (eds.) (1999). ''Handbook of the Birds of the World. Volume 5: Barn-Owls to Hummingbirds.'' Lynx Edicions. They tend to have large heads, short tails, cryptic plumage, and round facial discs around the eyes. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
