Brown Fish Owl
Encyclopedia
The Brown Fish Owl is an owl
. This species
is a part of the family
known as typical owl
s, Strigidae, which contains most living owls. It inhabits the warm subtropical and humid tropical parts of continental Asia
and some offshore islands.
The four fish owls were previously generally separated in the genus
Ketupa
. mtDNA cytochrome b
sequence
data is equivocal on which genus name is applied for them, and today they are commonly lumped
with the horned and eagle-owls (Bubo) – which they also resemble osteologically very much – for sake of convenience. Depending on whether some little-studied tropical eagle-owls are closer to the fish-owls than to the typical eagle-owls, Ketupa might be a valid genus if these as well as the fishing owls (formerly Scotopelia) are included in it.
with prominent "ear" tufts, typically around 55 centimetres (21.7 in) in length and weighing 2–2.5 kg (4.4–5.5 ) when fully grown. Subspecies
differ in size and males are smaller than females, with the smallest birds not quite 50 cm (19.7 in) long and weighing as little as 1100 grams (38.8 oz).
The upperparts are reddish brown and heavily streaked with black or dark brown. The underparts are buff to whitish, with dark streaks and finer brown barring. The throat is white and can be conspicuously puffed, while the facial disk is indistinct. The irides
are yellow, the feet a duller yellow, and the bill is dark. Sexes do not differ in appearance except for size.
Its calls are described as a deep tu-hoo-hoo or a soft huphuphuphuphuphup or a loud huhuhuhuhuhuhu.
are accepted today:
In prehistoric times, this species may have been present across the central and eastern Mediterranean basin, in particular on islands. The Late Pleistocene
Bubo insularis is typically considered to include the fragmentary remains originally described as Ophthalmomegas lamarmorae due to a mix-up with the fossil
macaque
Macaca majori
and subsequently unstudied for many decades. Its fossil bones suggest a bird the size of a large Spotted Eagle-Owl (B. africanus), a bit smaller still than the smallest living Brown Fish Owls. It was certainly smallish but long-legged by eagle-owl standards, and its wing proportions differed conspicuously from a typical Bubo. On the other hand, its leg and foot bones were more similar to those of a typical eagle-owl. Some consider them a specialized paleosubspecies of the Brown Fish Owl:
Its oldest remains date back at least to the Early Pliocene, about 5 million years ago (Ma). It was widely distributed around 120,000 years ago. After the onset of the last glacial period, less than 100,000 years ago, this population disappeared from the western part of its range, while in the Middle East
semenowi – fossil
bones indistinguishable from which are known since about the Gelasian
, c. 2 Ma – would have subsumed any remnants of the eastern Mediterranean population. The Late Miocene
-Early Pliocene taxon
"Strix
" perpasta is unlikely to belong in that genus, and also sometimes merged with B. (z.) insularis.
This species is an all-year resident throughout most tropical and subtropical parts of the Indian Subcontinent
to Southeast Asia
and southeastern China
; it is also found on Sri Lanka
. West of its main range, it is patchily distributed to the Levant
(possibly extinct) and southern Asia Minor
(recently rediscovered). It inhabits mainly the lowlands, in well-wooded habitat
, from open woodland to dense forest as well as in plantations; in the Himalayas
foothills
it ranges into submontane forest up to 1,500 m ASL
or so but not higher. Western birds are found in semiarid landscape and may breed in oases in arid
regions. Regardless of habitat, it rarely strays far from larger bodies of water such as rivers and lakes.
This species is very nocturnal but it can often be located by the small birds that mob
it while it is roosting in a tree. It feeds mainly on fish
es, frog
s and aquatic
crustacean
s; amniote
s, in particular terrestrial
ones, are seldom taken. If hungry, Brown Fish Owls will scavenge carrion
.
As mentioned above, the prehistoric B. insularis is sometimes included in the Brown Fish Owl. If this is correct, the different foot anatomy
, more similar to that of a typical eagle-owl, would imply that the population had shifted back to terrestrial prey. A likely prey item in this case would have been the Sardinian Pika
(Prolagus sardus). It has been conjectured that the owls disappeared with their prey due to climate change
, but the giant pikas of Sardinia and Corsica
still existed around 1750, finally succumbing to habitat destruction
, introduced predatory mammals and overhunting soon thereafter.
Brown Fish Owls breed from November to March. The clutch
is one or two eggs, often placed in an old stick nest of other birds, otherwise in a rock crevice or similar. Incubation is 38 days or somewhat less, and the young fledge
after about 7 weeks.
The Brown Fish Owl is not considered a threatened species
by the IUCN. Being a large predatory bird, it is only rarely found at a high population density
. Habitat destruction
will eventually cause the species to desert a region, and probably because of this it seems to be extinct as a breeding bird in Israel
nowadays.
Owl
Owls are a group of birds that belong to the order Strigiformes, constituting 200 bird of prey species. Most are solitary and nocturnal, with some exceptions . Owls hunt mostly small mammals, insects, and other birds, although a few species specialize in hunting fish...
. This 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...
is a part of the 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...
known as 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, which contains most living owls. It inhabits the warm subtropical and humid tropical parts of continental Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
and some offshore islands.
The four fish owls were previously generally separated in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Ketupa
Ketupa
Fish owls are a group of Asian owls in the Strigidae family. The owls are sometimes placed in their own genus Ketupa, but should arguably be merged with Bubo.It contains the following species:* Blakiston's Fish Owl,...
. mtDNA cytochrome b
Cytochrome b
Cytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...
sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
data is equivocal on which genus name is applied for them, and today they are commonly lumped
Lumpers and splitters
Lumping and splitting refers to a well-known problem in any discipline which has to place individual examples into rigorously defined categories. The lumper/splitter problem occurs when there is the need to create classifications and assign examples to them, for example schools of literature,...
with the horned and eagle-owls (Bubo) – which they also resemble osteologically very much – for sake of convenience. Depending on whether some little-studied tropical eagle-owls are closer to the fish-owls than to the typical eagle-owls, Ketupa might be a valid genus if these as well as the fishing owls (formerly Scotopelia) are included in it.
Description
It is a large owlOwl
Owls are a group of birds that belong to the order Strigiformes, constituting 200 bird of prey species. Most are solitary and nocturnal, with some exceptions . Owls hunt mostly small mammals, insects, and other birds, although a few species specialize in hunting fish...
with prominent "ear" tufts, typically around 55 centimetres (21.7 in) in length and weighing 2–2.5 kg (4.4–5.5 ) when fully grown. Subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
differ in size and males are smaller than females, with the smallest birds not quite 50 cm (19.7 in) long and weighing as little as 1100 grams (38.8 oz).
The upperparts are reddish brown and heavily streaked with black or dark brown. The underparts are buff to whitish, with dark streaks and finer brown barring. The throat is white and can be conspicuously puffed, while the facial disk is indistinct. The irides
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...
are yellow, the feet a duller yellow, and the bill is dark. Sexes do not differ in appearance except for size.
Its calls are described as a deep tu-hoo-hoo or a soft huphuphuphuphuphup or a loud huhuhuhuhuhuhu.
Subspecies
Three or four living subspeciesSubspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
are accepted today:
- B. z. zeylonensis (Gmelin, 1788) – Sri Lankan Brown Fish Owl. Sri LankaSri LankaSri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
.
- Small and dark.
- B. z. leschenault (TemminckCoenraad Jacob TemminckCoenraad Jacob Temminck was a Dutch aristocrat and zoologist.Temminck was the first director of the National Natural History Museum at Leiden from 1820 until his death. His Manuel d'ornithologie, ou Tableau systematique des oiseaux qui se trouvent en Europe was the standard work on European birds...
, 1820) – Common Brown Fish Owl. Indian subcontinentIndian subcontinentThe Indian subcontinent, also Indian Subcontinent, Indo-Pak Subcontinent or South Asian Subcontinent is a region of the Asian continent on the Indian tectonic plate from the Hindu Kush or Hindu Koh, Himalayas and including the Kuen Lun and Karakoram ranges, forming a land mass which extends...
to MyanmarMyanmarBurma , officially the Republic of the Union of Myanmar , is a country in Southeast Asia. Burma is bordered by China on the northeast, Laos on the east, Thailand on the southeast, Bangladesh on the west, India on the northwest, the Bay of Bengal to the southwest, and the Andaman Sea on the south....
(except NE) and ThailandThailandThailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
. Might include orientalis.
- B. z. leschenault (Temminck
- Larger and lighter than zeylonensis.
- B. z. semenowi (Zarudny, 1905) – Western Brown Fish Owl. LevantLevantThe Levant or ) is the geographic region and culture zone of the "eastern Mediterranean littoral between Anatolia and Egypt" . The Levant includes most of modern Lebanon, Syria, Jordan, Israel, the Palestinian territories, and sometimes parts of Turkey and Iraq, and corresponds roughly to the...
(possibly extinct) and S Asia MinorAsia MinorAsia Minor is a geographical location at the westernmost protrusion of Asia, also called Anatolia, and corresponds to the western two thirds of the Asian part of Turkey...
through MesopotamiaMesopotamiaMesopotamia is a toponym for the area of the Tigris–Euphrates river system, largely corresponding to modern-day Iraq, northeastern Syria, southeastern Turkey and southwestern Iran.Widely considered to be the cradle of civilization, Bronze Age Mesopotamia included Sumer and the...
(no up-to-date observations) to PakistanPakistanPakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...
.
- B. z. semenowi (Zarudny, 1905) – Western Brown Fish Owl. Levant
- Paler than leschenault. Possibly a separate species.
- B. z. orientalis DelacourJean Théodore DelacourJean Théodore Delacour was an American ornithologist of French origin. He was renowned for not only discovering but also rearing some of the rarest birds in the world...
, 1926 – Eastern Brown Fish Owl. NE Myanmar, VietnamVietnamVietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
and SE ChinaChinaChinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
. Doubtfully distinct from leschenault.
- B. z. orientalis Delacour
- Darker than leschenault.
In prehistoric times, this species may have been present across the central and eastern Mediterranean basin, in particular on islands. The Late Pleistocene
Late Pleistocene
The Late Pleistocene is a stage of the Pleistocene Epoch. The beginning of the stage is defined by the base of the Eemian interglacial phase before the final glacial episode of the Pleistocene 126,000 ± 5,000 years ago. The end of the stage is defined exactly at 10,000 Carbon-14 years BP...
Bubo insularis is typically considered to include the fragmentary remains originally described as Ophthalmomegas lamarmorae due to a mix-up with the fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
macaque
Macaque
The macaques constitute a genus of Old World monkeys of the subfamily Cercopithecinae. - Description :Aside from humans , the macaques are the most widespread primate genus, ranging from Japan to Afghanistan and, in the case of the barbary macaque, to North Africa...
Macaca majori
Macaca majori
Macaca majori was a prehistoric Macaque from the Pleistocene of Sardinia, Italy...
and subsequently unstudied for many decades. Its fossil bones suggest a bird the size of a large Spotted Eagle-Owl (B. africanus), a bit smaller still than the smallest living Brown Fish Owls. It was certainly smallish but long-legged by eagle-owl standards, and its wing proportions differed conspicuously from a typical Bubo. On the other hand, its leg and foot bones were more similar to those of a typical eagle-owl. Some consider them a specialized paleosubspecies of the Brown Fish Owl:
- B. z. insularis Mourer-Chauviré & Weesie, 1986
Its oldest remains date back at least to the Early Pliocene, about 5 million years ago (Ma). It was widely distributed around 120,000 years ago. After the onset of the last glacial period, less than 100,000 years ago, this population disappeared from the western part of its range, while in the Middle East
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far East...
semenowi – fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
bones indistinguishable from which are known since about the Gelasian
Gelasian
The Gelasian is an age in the international geologic timescale or a stage in chronostratigraphy, being the earliest or lowest subdivision of the Quaternary period/system and Pleistocene epoch/series. It spans the time between 2.588 ± 0.005 Ma and 1.806 ± 0.005 Ma...
, c. 2 Ma – would have subsumed any remnants of the eastern Mediterranean population. The Late Miocene
Late Miocene
The Late Miocene is a sub-epoch of the Miocene Epoch made up of two stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch....
-Early Pliocene taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
"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...
" perpasta is unlikely to belong in that genus, and also sometimes merged with B. (z.) insularis.
Ecology
Indian subcontinent
The Indian subcontinent, also Indian Subcontinent, Indo-Pak Subcontinent or South Asian Subcontinent is a region of the Asian continent on the Indian tectonic plate from the Hindu Kush or Hindu Koh, Himalayas and including the Kuen Lun and Karakoram ranges, forming a land mass which extends...
to Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
and southeastern China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
; it is also found on Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
. West of its main range, it is patchily distributed to the Levant
Levant
The Levant or ) is the geographic region and culture zone of the "eastern Mediterranean littoral between Anatolia and Egypt" . The Levant includes most of modern Lebanon, Syria, Jordan, Israel, the Palestinian territories, and sometimes parts of Turkey and Iraq, and corresponds roughly to the...
(possibly extinct) and southern Asia Minor
Asia Minor
Asia Minor is a geographical location at the westernmost protrusion of Asia, also called Anatolia, and corresponds to the western two thirds of the Asian part of Turkey...
(recently rediscovered). It inhabits mainly the lowlands, in well-wooded habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
, from open woodland to dense forest as well as in plantations; in the Himalayas
Himalayas
The Himalaya Range or Himalaya Mountains Sanskrit: Devanagari: हिमालय, literally "abode of snow"), usually called the Himalayas or Himalaya for short, is a mountain range in Asia, separating the Indian subcontinent from the Tibetan Plateau...
foothills
Foothills
Foothills are geographically defined as gradual increases in elevation at the base of a mountain range. They are a transition zone between plains and low relief hills to the adjacent topographically high mountains.-Examples:...
it ranges into submontane forest up to 1,500 m ASL
Above mean sea level
The term above mean sea level refers to the elevation or altitude of any object, relative to the average sea level datum. AMSL is used extensively in radio by engineers to determine the coverage area a station will be able to reach...
or so but not higher. Western birds are found in semiarid landscape and may breed in oases in arid
Arid
A region is said to be arid when it is characterized by a severe lack of available water, to the extent of hindering or even preventing the growth and development of plant and animal life...
regions. Regardless of habitat, it rarely strays far from larger bodies of water such as rivers and lakes.
This species is very nocturnal but it can often be located by the small birds that mob
Mobbing behavior
Mobbing in animals is an antipredator behavior which occurs when individuals of a certain species mob a predator by cooperatively attacking or harassing it, usually to protect their offspring. A simple definition of mobbing is an assemblage of individuals around a potentially dangerous predator...
it while it is roosting in a tree. It feeds mainly on 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...
es, frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
s and aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s; amniote
Amniote
The amniotes are a group of tetrapods that have a terrestrially adapted egg. They include synapsids and sauropsids , as well as their fossil ancestors. Amniote embryos, whether laid as eggs or carried by the female, are protected and aided by several extensive membranes...
s, in particular terrestrial
Terrestrial animal
Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...
ones, are seldom taken. If hungry, Brown Fish Owls will scavenge carrion
Carrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
.
As mentioned above, the prehistoric B. insularis is sometimes included in the Brown Fish Owl. If this is correct, the different foot anatomy
Anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...
, more similar to that of a typical eagle-owl, would imply that the population had shifted back to terrestrial prey. A likely prey item in this case would have been the Sardinian Pika
Sardinian Pika
The Sardinian Pika was a primitive lagomorph native to the Mediterranean islands of Sardinia and Corsica until its extinction around the year 1800...
(Prolagus sardus). It has been conjectured that the owls disappeared with their prey due to climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
, but the giant pikas of Sardinia and Corsica
Corsica
Corsica is an island in the Mediterranean Sea. It is located west of Italy, southeast of the French mainland, and north of the island of Sardinia....
still existed around 1750, finally succumbing to habitat destruction
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
, introduced predatory mammals and overhunting soon thereafter.
Brown Fish Owls breed from November to March. The clutch
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...
is one or two eggs, often placed in an old stick nest of other birds, otherwise in a rock crevice or similar. Incubation is 38 days or somewhat less, and the young fledge
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...
after about 7 weeks.
The Brown Fish Owl is not considered a threatened species
Threatened species
Threatened species are any speciesg animals, plants, fungi, etc.) which are vulnerable to endangerment in the near future.The World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories,...
by the IUCN. Being a large predatory bird, it is only rarely found at a high population density
Population density
Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans...
. Habitat destruction
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
will eventually cause the species to desert a region, and probably because of this it seems to be extinct as a breeding bird in Israel
Israel
The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...
nowadays.