The true owls or typical owls (

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Strigidae) are one of the two generally accepted families of

owl Owls are birds from the order Strigiformes (), which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers a ...

s, the other being the barn owls and bay owls (

Tytonidae The bird family Tytonidae, which includes the barn owls ''Tyto'' and the bay owls ''Phodilus'', is one of the two Family (biology), families of owls, the other being the true owls or typical owls, True owl, Strigidae. They are medium to large owl ...

). This large family comprises 230 living or recently extinct

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

in 24

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

. The Strigidae owls have a

cosmopolitan distribution In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and en ...

and are found on every continent except

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

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 The Eurasian eagle-owl (''Bubo bubo'') is a species of eagle-owl, a type of bird that resides in much of Eurasia. It is often just called the eagle-owl in Europe and Asia. It is one of the largest species of owl. Females can grow to a total le ...

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 The ''Handbook of the Birds of the World'' (HBW) is a multi-volume series produced by the Spanish publishing house Lynx Edicions in partnership with BirdLife International. It is the first handbook to cover every known living species of bird. ...

. Volume 5: Barn-Owls to Hummingbirds.'' Lynx Edicions. They tend to have large heads, short tails, cryptic

plumage Plumage () is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, there can b ...

, and round facial discs around the eyes. The family is generally

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...

(with a few exceptions like the

burrowing owl The burrowing owl (''Athene cunicularia''), also called the shoco, is a small, long-legged, primarily terrestrial—though not flightless—species of owl native to the open landscapes of North and South America. They are typically found in gra ...

) and obtain their food on the wing. The wings are large, broad, rounded, and long. As is the case with most

birds of prey Birds of prey or predatory birds, also known as (although not the same as) raptors, are hypercarnivorous bird species that actively predation, hunt and feed on other vertebrates (mainly mammals, reptiles and smaller birds). In addition to speed ...

, in many owl species females are larger than males. Because of their

nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...

habits, they tend not to exhibit

sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

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 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 the genus '' Glaucidium'' and the

northern hawk-owl The northern hawk-owl or northern hawk owl (''Surnia ulula'') is a medium-sized true owl of the northern latitudes. It is non-migratory and usually stays within its breeding range, though it sometimes irrupts southward. It is one of the few 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 Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...

function, breaking up the outline of a roosting bird. The feathers of the

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 ...

are arranged in order to increase sound delivered to 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 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 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 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 the brain. Several owl species also have fluorescent pigments called

porphyrin Porphyrins ( ) are heterocyclic, macrocyclic, organic compounds, composed of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges (). In vertebrates, an essential member of the porphyrin group is heme, w ...

s 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 the age of owls. The relative ages of the feathers are differentiated by the intensity of fluorescence that they emit when the

primaries Primary elections or primaries are elections held to determine which candidates will run in an upcoming general election. In a partisan primary, a political party selects a candidate. Depending on the state and/or party, there may be an "open pri ...

and secondaries are exposed to

black light A blacklight, also called a UV-A light, Wood's lamp, or ultraviolet light, is a lamp (fixture), lamp that emits long-wave (UV-A) ultraviolet light and very little visible light. One type of lamp has a violet light filter, filter material, eith ...

. This method helps to detect the subtle differences between third and fourth generation feathers, whereas looking at wear and color makes age determination difficult.

Niche competition

It has been noted that there is some competition for niche space between the

spotted owl The spotted owl (''Strix occidentalis'') is a species of true owl. It is a resident species of old-growth forests in western North America, where it nests in tree hollows, old bird of prey nests, or rock crevices. Nests can be between high a ...

and the

barred owl The barred owl (''Strix varia''), also known as the northern barred owl, striped owl or, more informally, hoot owl or eight-hooter owl, is a North American large species of owl. A member of the true owl family, Strigidae, they belong to the genus ...

(both of which are true owls) . This competition is related to

deforestation Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. Ab ...

, and therefore a reduction in niche quantity and quality. This deforestation is more specifically the result of

overlogging Overlogging is a form of overexploitation caused by legal or illegal logging activities that lead to unsustainable or irrecoverable deforestation and permanent habitat destruction for forest wildlife. Causes The use of poor logging practices ...

and

forest fires A forest fire A wildfire, forest fire, or a bushfire is an unplanned and uncontrolled fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identified as a bushfire ( in Au ...

. These two species of owl are known to traditionally live in mature forests of old and tall trees, which are now mostly limited to

public land In all modern states, a portion of land is held by central or local governments. This is called public land, state land, or Crown land (Commonwealth realms). The system of tenure of public land, and the terminology used, varies between countries. ...

s. As niche overlap is occurring in these two families, there is a concern with the barred owls encroaching on the spotted owl's

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

n 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 The northern spotted owl (''Strix occidentalis caurina'') is one of three spotted owl subspecies. A western North American bird in the family Strigidae, genus ''Strix (genus), Strix'', it is a medium-sized dark brown owl native to the Pacific N ...

shares its territories and competes with other species, it is declining at a more rapid pace. This invasion by barred owls occurred about 50 years ago in the

Pacific Northwest The Pacific Northwest (PNW; ) is a geographic region in Western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though no official boundary exists, the most common ...

, and despite their low numbers, they are considered an

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

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 Local extinction, also extirpation, is the termination of a species (or other taxon) in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with extinction, global extinctions. Local extinctions ...

. It is thought that the rapid decrease in population size of spotted owls will cause a

trophic cascade Trophic cascades are powerful indirect interactions that can control entire ecosystems, occurring when a trophic level in a food web is suppressed. For example, a top-down cascade will occur if predators are effective enough in predation to redu ...

, since the spotted owls help provide a healthy

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

Behaviour

Owls are generally

and/or

crepuscular In zoology, a crepuscular animal is one that is active primarily during the twilight period, being matutinal (active during dawn), vespertine (biology), vespertine/vespertinal (active during dusk), or both. This is distinguished from diurnalit ...

and spend much of the day

roosting Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight ...

. 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

and the inconspicuous locations they adopt are an effort to avoid predators and

mobbing Mobbing, as a sociological term, refers either to bullying in any context, or specifically to that within the workplace, especially when perpetrated by a group rather than an individual. Psychological and health effects Victims of workplace mo ...

by small birds.

Communication

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 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 A territory is an area of land, sea, or space, belonging or connected to a particular country, person, or animal. In international politics, a territory is usually a geographic area which has not been granted the powers of self-government, ...

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 the feathers of their prey to signal their breeding status to members within the same species.

Migration

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.

Habitat, climate and seasonal changes

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 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.

Parasites

Avian malaria or ''

Plasmodium relictum ''Plasmodium relictum'' is a species in the genus ''Plasmodium,'' subgenus '' Haemamoeba''. It is a parasite, and the most common cause of malaria in birds. Like all ''Plasmodium'' species, ''P. relictum'' has both vertebrate and insect hosts. ...

'' affects owls and specifically, 44% of northern and Californian spotted owls harbor 17 strains of 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.

Predators

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 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.

Systematics

The

Strigidae was introduced by the English zoologist

William Elford Leach William Elford Leach (2 February 1791 – 25 August 1836) was an English zoologist and marine biologist. Life and work Elford Leach was born at Hoe Gate, Plymouth, the son of an attorney. At the age of twelve he began a medical apprenticesh ...

in a guide to the contents of the

British Museum The British Museum is a Museum, public museum dedicated to human history, art and culture located in the Bloomsbury area of London. Its permanent collection of eight million works is the largest in the world. It documents the story of human cu ...

published in 1819. A

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

study of the owls by Jessie Salter and collaborators published in 2020 found that the family Strigidae was divided into two

sister A sister is a woman or a girl who shares parents or a parent with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to ref ...

clades and some of the traditional genera were

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

. 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 Pamela Cecile Rasmussen (born October 16, 1959) is an American ornithology, ornithologist and expert on Asian birds. She was formerly a research associate at the Smithsonian Institution in Washington, D.C., and is based at the Michigan State Uni ...

and David Donsker updated the online list of world birds that they maintain on behalf of the

International Ornithological Committee The International Ornithologists' Union (IOU) is an international organization for the promotion of ornithology. It links basic and applied research and nurtures education and outreach activities. Specifically, the IOU organizes and funds global co ...

(IOC). The

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

below 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''. Bubo blakistoni

The 235 extant or recently extinct

are assigned to 23

Forest_Owlet_Athene_blewitti_by_Ashahar_alias_Krishna_Khan

* Genus '' Uroglaux'' – Papuan hawk-owl * Genus ''

Ninox ''Ninox'' is a genus of true owls comprising 36 species found in Asia and Australasia. Many species are known as hawk-owls or boobooks, but the northern hawk-owl (''Surnia ulula'') is not a member of this genus. Taxonomy The genus was introduce ...

'' – Australasian hawk-owls, 37 species of which one is recently extinct * Genus '' Margarobyas'' – bare-legged owl or Cuban screech-owl * Genus '' Taenioptynx'' – two species previous placed in ''Glaucidium'' * Genus '' Micrathene'' – elf owl * Genus '' Xenoglaux'' – long-whiskered owlet * Genus '' Aegolius'' – saw-whet owls, five species of which one is recently extinct * Genus '' Athene'' – nine species * Genus '' Surnia'' – northern hawk-owl * Genus '' Glaucidium'' – pygmy owls, 29 species * Genus '' Otus'' – scops owls, 58 species including three extinct species formerly placed in ''Mascarenotus'' * Genus ''

Ptilopsis ''Ptilopsis'' is a genus of typical owls, or true owls, in the family Strigidae, that inhabits Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million squ ...

'' – white-faced owls, two species * Genus ''

Asio ''Asio'' is a genus of typical owls, or true owls, in the family Strigidae. This group has representatives over most of the planet, and the short-eared owl is one of the most widespread of all bird species, breeding in Europe, Asia, North Ameri ...

'' – eared owls, nine species * Genus '' Jubula'' – maned owl * Genus ''

Bubo A bubo (Greek βουβών, ''boubṓn'', 'groin') is adenitis or inflammation of the lymph nodes and is an example of reactive infectious lymphadenopathy. Classification Buboes are a symptom of bubonic plague and occur as painful swellings in ...

'' – eagle-owls, horned-owls and snowy owl, 10 species * Genus ''

Scotopelia Fishing owls form the genus, ''Scotopelia'', of sub-Saharan African birds in the family true owl, Strigidae, the true owls. The genus is closely related to the genus ''Ketupa'', and may be embedded within it. The genus contains three species: ...

'' – fishing owls, three species * Genus ''

Ketupa ''Ketupa'' is a genus of owls in the family Strigidae. The genus formerly contained just three species, the fish owls but based on the results from a genetic study published in 2020, the generic boundaries were altered. The genus now contains twe ...

'' – fish owls and eagle-owls, 12 species (including 9 species previously placed in ''Bubo'') * Genus '' Psiloscops'' – flammulated owl * Genus '' Gymnasio'' – Puerto Rican owl * Genus ''

Megascops Screech owls are typical owls (Strigidae) belonging to the genus ''Megascops'' with 22 living species. For most of the 20th century, this genus was merged with the Old World scops owls in ''Otus'', but nowadays it is again considered separat ...

'' – screech-owls, 25 species * Genus '' Pulsatrix'' – spectacled owls, three species * Genus '' Lophostrix'' – crested owl * Genus '' Strix'' – earless owls, 22 species, including four previously placed in ''Ciccaba''

Late Quaternary prehistoric extinctions

* Genus '' Grallistrix'' – stilt-owls, four species ** Kaua‘i stilt-owl, ''Grallistrix auceps'' ** Maui stilt-owl, ''Grallistrix erdmani'' ** Moloka‘i stilt-owl, ''Grallistrix geleches'' ** O‘ahu stilt-owl, ''Grallistrix orion'' * Genus ''

Ornimegalonyx The giant Cuban owl or giant cursorial owl (''Ornimegalonyx'') is an extinct genus of giant owl that measured in height. It is closely related to the many species of living owls of the genus ''Strix (genus), Strix''.Feduccia, Alan (1996) "The Ori ...

'' – Caribbean giant owls, one or two species ** Cuban giant owl, ''Ornimegalonyx oteroi'' **''Ornimegalonyx'' sp. – probably subspecies of ''O. oteroi'' * Genus '' Asphaltoglaux'' ** Asphalt miniature owl, ''Asphaltoglaux cecileae'' *Genus ''

Oraristrix ''Oraristix brea'', the La Brea owl, is an extinct owl reported from the Upper Pleistocene asphalt deposits of the La Brea Tar Pits in Los Angeles, California. It was first described in 1933 by Hildegarde Howard as ''Strix brea'', but this extin ...

'' ** La Brea owl, ''Oraristrix brea'' Ornimegalonyx oteroi

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...
record

* ''

Mioglaux ''Mioglaux'' is an extinct genus of strigid that lived during the Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquit ...

'' (Late Oligocene? – Early Miocene of WC Europe) – includes ''"Bubo" poirreiri'' * '' Intulula'' (Early/Middle Miocene of WC Europe) – includes ''"Strix/Ninox" brevis'' * '' Yarquen'' (Middle Miocene of Argentina) * '' Alasio'' (Middle Miocene of Vieux-Collonges, France) – includes ''"Strix" collongensis'' The fossil database for Strigiformes 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: *''"Otus/Strix" wintershofensis'' –

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

(Early/Middle Miocene of Wintershof West, Germany) – may be close to extant genus ''Ninox'' * ''"Strix" edwardsi'' –

(Middle Miocene of Grive-Saint-Alban, France) * ''"Asio" pygmaeus'' –

(Early Pliocene of

Odesa Odesa, also spelled Odessa, is the third most populous List of cities in Ukraine, city and List of hromadas of Ukraine, municipality in Ukraine and a major seaport and transport hub located in the south-west of the country, on the northwestern ...

, Ukraine) * Strigidae gen. et sp. indet. UMMP V31030 (Rexroad Late Pliocene of Kansas, USA) – ''Strix''/''Bubo''? * Ibiza owl, Strigidae gen. et sp. indet. –

prehistoric Prehistory, also called pre-literary history, is the period of human history between the first known use of stone tools by hominins million years ago and the beginning of recorded history with the invention of writing systems. The use o ...

(Late Pleistocene/Holocene of Es Pouàs, Ibiza) The supposed fossil

heron Herons are long-legged, long-necked, freshwater and coastal birds in the family Ardeidae, with 75 recognised species, some of which are referred to as egrets or bitterns rather than herons. Members of the genus ''Botaurus'' are referred to as bi ...

''"Ardea" lignitum'' (Late Pliocene of Germany) was apparently a strigid owl, possibly close to ''Bubo''.Olson, p. 167 The Early–Middle

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

genus '' Palaeoglaux'' from west-central Europe is sometimes placed here, but given its age, it is probably better considered its own family for the time being.

References

Bibliography

*Olson, Storrs L. (1985). The fossil record of birds. ''In:'' Farner, D.S.; King, J.R. & Parkes, Kenneth C. (eds.): ''Avian Biology'' 8: 79–238. Academic Press, New York.

External links

ITIS – Strigidae TaxonomyTypical owl videos
on the Internet Bird Collection
The Owl Pages
about owls – photos, calls, books, art, mythology and more. {{Authority control Owls *