{{Short description|Species of owl}} {{Speciesbox | image = Brown fishing owl.jpg | image_caption =Brown fish owl in Biligiriranga Hills |image2=Brown fish owl.ogg |image2_caption=Calls (South India) | status = LC | status_system = IUCN3.1 | status_ref = <ref name=iucn>{{cite iucn |title=''Ketupa zeylonensis'' |author=BirdLife International |date=2016 |article-number=e.T22689012A90010491 |doi=10.2305/IUCN.UK.2016-3.RLTS.T22689012A90010491.en |access-date=3 February 2022}}</ref> | status2 = CITES_A2 | status2_system = CITES | status2_ref = <ref name=iucn/> | taxon = Ketupa zeylonensis | authority = (Gmelin, JF, 1788) | subdivision_ranks = Subspecies | subdivision = See text | synonyms = * ''Bubo zeylonensis'' * ''Strix zeylonensis'' <small>Gmelin, 1788</small> and see text | range_map = KetupaZeylonensisIUCN2019-2.png | range_map_caption = Range of brown fish owl {{leftlegend|#008000|Resident|outline=gray}} {{leftlegend|#AAFFAA|Possibly Extant (resident)|outline=gray}} }} [[File:Insta 02.jpg|thumb|At Ranthambore National Park]] The '''brown fish owl''' ('''''Ketupa zeylonensis''''') is a fish owl species in the family known as typical owls, Strigidae. It is native from Turkey to South and Southeast Asia. Due its wide distribution it is listed as Least Concern on the IUCN Red List.<ref name=iucn /> It inhabits forests and wooded wetlands.<ref name=Grimmett_al2016>{{cite book |author1=Grimmett, R. |author2=Inskipp, C. |author3=Inskipp, T. |year=2016 |title=Birds of the Indian Subcontinent: India, Pakistan, Sri Lanka, Nepal, Bhutan, Bangladesh and the Maldives |series=Helm Field Guides |location=London |publisher=Bloomsbury Publishing |chapter=Brown Fish Owl ''Ketupa zeylonensis'' |chapter-url=https://books.google.com/books?id=HvY0DQAAQBAJ&pg=PA222 |page=222 |isbn=978-1-4081-6265-1}}</ref> Of the four living species of fish owl, it is the most widely distributed, most common and best-studied. It occupies a range of over {{convert|7000|km|mi|abbr=on}}.
==Taxonomy== [[File:SL Yala NP BlockV asv2020-01 img05.jpg|thumb|right|A brown fish owl of the nominate subspecies ''zeylonensis'', which is smaller and darker than other subspecies]] thumb|right|A brown fish owl in India The brown fish owl was formally described in 1788 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's ''Systema Naturae''. He placed it with the other owls in the genus ''Strix'' and coined the binomial name ''Strix zeylonensis''.<ref>{{ cite book | last=Gmelin | first=Johann Friedrich | author-link=Johann Friedrich Gmelin| year=1788 | title=Systema naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis | edition=13th | volume=1, Part 1 | language=Latin | location=Lipsiae [Leipzig] | publisher=Georg. Emanuel. Beer | page=287 | url=https://www.biodiversitylibrary.org/page/2896887 }}</ref> Gmelin based his description on the "Great Ceylonese horned owl" that had been described and illustrated by the naturalist Peter Brown in his book ''New Illustrations of Zoology''. Joan Gideon Loten, an administrator in the Dutch East India Company had provided Brown with a picture of the owl that had been drawn by the Ceylonese artist Pieter Cornelis de Bevere.<ref>{{ cite book | last=Brown | first=Peter | author-link=Peter Brown (naturalist) | date=1776 | title=Nouvelles illustrations de zoologie: contenant cinquante planches enlumineés d'oiseaux curieux, et qui non etés jamais descrits, et quelques de quadrupedes, de reptiles et d'insectes, avec de courtes descriptions systematiques | trans-title=New illustrations of zoology, containing fifty coloured plates of new, curious, and non-descript birds, with a few quadrupeds, reptiles and insects | location=London | publisher=Imprimé pour B. White | page=8, Plate 4 | url=https://www.biodiversitylibrary.org/page/27845739 }}</ref><ref>{{cite journal | last=Ferguson | first=Donald | year=1907 |title=Joan Gideon Loten F.R.S., the naturalist governor of Ceylon (1752-57), and the Ceylonese artist de Bevere | url=https://archive.org/details/journalofceylonb19roya/page/217/mode/1up | journal=Journal of the Ceylon Branch of the Royal Asiatic Society | volume=19 | pages=217–271 }}</ref> The brown fish owl is now placed in the genus ''Ketupa'' that was introduced in 1830 by the French naturalist René Lesson.<ref>{{ cite book | last=Lesson | first=René | author-link=René Lesson | year=1831 | title=Traité d'Ornithologie, ou Tableau Méthodique | volume=1 | language=French | location=Paris | publisher=F.G. Levrault | page=114 (livraison 2) | url=https://www.biodiversitylibrary.org/page/35997098 }} Published in 8 ''livraisons'' between 1830 and 1831. For the publication date see: {{ cite book | last1=Dickinson | first1=E.C. | author1-link=Edward C. Dickinson | last2=Overstreet | first2=L.K. | last3=Dowsett | first3=R.J. | last4=Bruce | first4=M.D. | year=2011 | title=Priority! The Dating of Scientific Names in Ornithology: a Directory to the literature and its reviewers | location=Northampton, UK | publisher=Aves Press | isbn=978-0-9568611-1-5 | page=119 | url=https://www.researchgate.net/publication/267763194 }} </ref><ref name=ioc>{{cite web| editor1-last=Gill | editor1-first=Frank | editor1-link=Frank Gill (ornithologist) | editor2-last=Donsker | editor2-first=David | editor3-last=Rasmussen | editor3-first=Pamela | editor3-link=Pamela Rasmussen | date=August 2022 | title=Owls | work=IOC World Bird List Version 12.2 | url=https://www.worldbirdnames.org/bow/owls/ | publisher=International Ornithologists' Union | access-date=24 December 2022 }}</ref>
Four subspecies are recognised:<ref name=ioc/> * ''K. z. semenowi'' Zarudny, 1905 – southeast Turkey, Middle East to northwest India<ref>{{cite journal |author=Sarudny, N. |year=1905 |title=Zwei ornithologische Neuheiten aus West-Persien |journal=Ornithologisches Jahrbuch |volume=16 |pages=141–142 |url=https://archive.org/details/ornithologische161905hall/page/141}}</ref> * ''K. z. leschenaulti'' (Temminck, 1820) – India through Myanmar to west Thailand<ref>{{cite book |author=Temminck, C. J. |year=1838 |title=Nouveau recueil de planches coloriées d'oiseaux: pour servir de suite et de complément aux planches enluminées de Buffon, édition in-folio et in-4⁰ de l'Imprimerie royale, 1770 |volume=II |location=Paris, Strasbourgh, Amsterdam |publisher=F. G. Levrault, Legras Imbert et Comp. |chapter=Hibou Leschenault. ''Strix Leschenault'' |chapter-url=https://archive.org/details/Nouveaurecueild2Temm/page/20}}</ref> * ''K. z. zeylonensis'' (Gmelin, JF, 1788) – Sri Lanka * ''K. z. orientalis'' Delacour, 1926 – northeast Myanmar to southeast China, Indochina and the Malay Peninsula<ref>{{cite journal |author=Delacour, J. F. |year=1926 |title=''Ketupa celonensis orientalis'' |journal=Bulletin of the British Ornithologists' Club |volume=47 |issue=308 |page=11 |url=https://archive.org/details/bulletinofbritis47tayl/page/11}}</ref>
Results of a phylogenetic analysis of nine horned owl species indicate that ''Ketupa'' species form a monophyletic group.<ref>{{cite journal |author1=Omote, K. |author2=Nishida, C. |author3=Dick, M. H. |author4=Masuda, R. |year=2013 |title=Limited phylogenetic distribution of a long tandem-repeat cluster in the mitochondrial control region in Bubo (Aves, Strigidae) and cluster variation in Blakiston's fish owl (''Bubo blakistoni'') |journal=Molecular Phylogenetics and Evolution |volume=66 |issue=3 |pages=889–897 |doi=10.1016/j.ympev.2012.11.015 |pmid=23211719 |bibcode=2013MolPE..66..889O }}</ref>
=== Fossil records === 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 fish owls. It was certainly smallish but long-legged by eagle-owl standards, and its wing proportions differed conspicuously from a typical horned eagle owl. On the other hand, its leg and foot bones were more similar to those of a typical eagle-owl. Some consider it a specialized paleosubspecies of the brown fish owl that became extinct during the third Würm glaciation,<ref name=Mourer-Chauviré1986>{{cite journal |author1=Mourer-Chauviré, C. |author2=Weesie, P. D. M. |year=1986 |title=''Bubo insularis'' n. sp., forme endemique insulaire de grand-duc (Aves, Strigiformes) du Pléistocène de Sardaigne et de Corse |journal=Revue de Paléobiologie |volume=5 |pages=197–205 |url=http://www2.nrm.se/ve/birds/sape/GlobalOwlProject/Fossil_owls/Bubo%20insularis%20%28Mourer-Chauvire%20%26%20Weesie%29%201986.pdf |access-date=2009-06-23 |archive-date=2021-08-16 |archive-url=https://web.archive.org/web/20210816175057/http://www2.nrm.se/ve/birds/sape/GlobalOwlProject/Fossil_owls/Bubo%20insularis%20%28Mourer-Chauvire%20%26%20Weesie%29%201986.pdf }}</ref><ref name=Mlíkovský2003>{{cite journal |author=Mlíkovský, J. |year=2003 |title=Brown Fish Owl (''Bubo zeylonensis'') in Europe: past distribution and taxonomic status |journal=Buteo |volume=13 |pages=61–65 |citeseerx=10.1.1.694.5550}}</ref> while others reported remains of ''B. "insularis"'' in the Holocene of Sardinia and until the beginning of Roman Sardinia, with no subspecies being recognized.<ref>{{cite journal |author1=Vigne, J.-D. |name-list-style=amp |author2=Bailon, S. |author3=Cuisin, J. |year=1997 |title=Biostratigraphy of amphibians, reptiles, birds and mammals in Corsica and the role of man in the Holocene faunal turnover |journal=Anthropologica |volume=25 |issue=26 |pages=587–604}}</ref>
The oldest remains date back at least to the Early Pliocene, about 5 million years ago. It was probably widely distributed around 120,000 years ago. After the onset of the last glacial period, less than 100,000 years ago, it disappeared from the western part of its range. The Late Miocene-Early Pliocene ''"Strix" perpasta'' is unlikely to belong in that genus, and also sometimes merged with ''B. insularis''.<ref name=Mlíkovský2003/>
==Description== [[File:Brown Fish Owl.jpg|thumb|A juvenile at Sim's Park, Coonoor, Tamil Nadu]] The brown fish owl has prominent ear tufts and rufous brown upperparts that are heavily streaked with black or dark brown. Its underparts are buffy-fulvous to whitish, with wavy dark brown streaks and finer brown barring. Its throat is white and conspicuously puffed. Its facial disk is indistinct, the bill dark and the iris golden yellow. Its featherless feet are yellow. Two-year old brown fish owls are somewhat paler than adults. Female and male differ slightly in size.<ref name= Mikkola>{{cite book |author=Mikkola, H. |year=2013 |title=Owls of the World: A Photographic Guide |publisher=Christopher Helm |location=London |isbn=978-1-4729-0593-2 |edition=Second |chapter=Brown Fish Owl ''Bubo zeylonensis'' |page=298}}</ref>
In body size, it ranges from {{convert|48|to|61|cm|in|abbr=on}} with a wingspan from {{convert|125|to|140|cm|in|abbr=on}}. Its weight varies considerably, ranging from {{convert|1.1|to|2.5|kg|lb|abbr=on}}. Some of the variability is attributed to the range of sizes across the subspecies. Also, females are invariably at least somewhat larger than males and condition of birds is variable.<ref name = gw9905>{{cite book |author=Grimmett, R., Inskipp, C., & Inskipp, T. |year=1999 |title=Birds of India, Pakistan, Nepal, Bangladesh, Bhutan, Sri Lanka, and the Maldives |publisher=Princeton University Press |location=Princeton }}</ref><ref>{{cite book |author=de Silva Wijeyeratne, G. |year=2017 |title=Photographic Field Guide to the Birds of Sri Lanka |publisher=John Beaufoy Publishing |location=Oxford |edition=Illustrated |isbn=978-1-909612-83-9 }}</ref> It is slightly larger than the buffy fish owl with a darker brown hue.<ref name= Konig>{{cite book |author=König, C. |author2=Weick, F. |title=Owls of the World |year=2010 |publisher=Christopher Helm |series=Helm Identification Guides |location=London |isbn=978-1-4081-0884-0 |edition=Second |chapter=Brown Fish Owl ''Bubo zeylonensis'' |page=343, Plate 38 }}</ref><ref name= Voous>{{cite book |author=Voous, K. H. |year=1989 |title=Owls of the Northern Hemisphere |publisher=The MIT Press |edition=Illustrated, reprinted |isbn=978-0-262-22035-4 }}</ref>
Compared to eagle owls of similar length, fish owls tend to be even shorter in tail length and even heavier in build, have relatively larger wings, have considerably longer legs, and have a rough texture to the bottom of their toes. At least the latter two features are clear adaptations to aid these owls in capturing fish. Diurnal raptors who feed largely on fish have similar, if not identical, rough texture under their toes, which helps these birds grasp slippery fish. Unlike diurnal raptors who capture fish such as the osprey (''Pandion haliaetus'') as compared to most terrestrial raptors, the fish owls have large, powerful, and curved talons and a longitudinal sharp keel sitting under the middle claw with all having sharp cutting edges that are very much like those of eagle owls. Also, unlike fish-eating diurnal raptors will not submerge any part of their body while hunting, preferring only to put their feet into the water, although fish owls will hunt on foot, wading into the shallows. Unlike most owls, the feathers of fish owls are not soft to the touch and they lack the comb and hair-like fringes to the primaries, which allow other owls to fly silently in order to ambush their prey. Due to the lack of these feather-specializations, fish owl wing beats make sounds. The brown fish owl in particular is said to have a noisy wing beat, sometimes described as producing a singing sound, but another description claimed they could be "as silent as any other owl" in flight. The lack of a deep facial disc in fish owls is another indication of the unimportance of sound relative to vision in these owls, as facial disc depth (as well as inner ear size) are directly related to how important sound is to an owl's hunting behavior. Also different from most any other kind of owl, the bill is placed on the face between the eyes rather below it, which is said to impart this fish owl with a "remarkably morose and sinister expression". Similar adaptations, such as unwillingness to submerge beyond their legs and lack of sound-muffling feathers are also seen in the African fishing owls, which do not seem to be directly related. The brown fish owl has sometimes been regarded as conspecific with the Blakiston's fish owl (''B. blakistoni''), but there is an approximately {{convert|2000|km|mi|abbr=on}} gap in their distributions, not to mention a large number of physical differences not the least of which is the Blakiston's considerably greater size.<ref name= Voous/><ref name= Konig/>
===Subspecies=== *Sri Lankan brown fish owl (''K. zeylonensis zeylonensis'') is the smallest and darkest coloured subspecies with a wing chord of {{convert|355|to|405|mm|in|abbr=on}}, a tarsus of {{convert|85|to|90|mm|in|abbr=on}}, a tail of {{convert|177|to|206|mm|in|abbr=on}}, and a bill of {{convert|42|to|48|mm|in|abbr=on}}. The wing length averages 92% shorter than in northern subspecies. One male was found to have weighed {{convert|1100|g|lb|abbr=on}}. *Common brown fish owl (''K. z. leschenaultii'') occurs from the Indian subcontinent to Myanmar and Thailand. It is of medium hue with lighter markings than the nominate subspecies. It has a wing chord of {{convert|370|to|430|mm|in|abbr=on}}, a tail of {{convert|186|to|210|mm|in|abbr=on}}, a tarsus of {{convert|71|to|90|mm|in|abbr=on}} and a bill of {{convert|49|to|52|mm|in|abbr=on}}. The wing chord of 16 males in India averaged {{convert|402|mm|in|abbr=on}} and their bills averaged {{convert|49|mm|in|abbr=on}} while 15 females averaged {{convert|395|mm|in|abbr=on}} in wing chord and {{convert|51.5|mm|in|abbr=on}} in bill length. A male was found to weigh {{convert|1105|g|lb|abbr=on}} and a female was found to weigh {{convert|1308|g|lb|abbr=on}}. *Western brown fish owl (''K. z. semenowi'') occurs from southern Turkey through Iran and Pakistan to northeastern India. It is paler and slightly larger than the common brown fish owl with a somewhat tawny hue. Its wing chord is {{convert|396|to|434|mm|in|abbr=on}} with a tarsus of {{convert|74|to|90|mm|in|abbr=on}}, a tail of {{convert|197|to|214|mm|in|abbr=on}} and a bill of {{convert|49|to|54|mm|in|abbr=on}}. *Eastern brown fish owl (''K. z. orientalis'') occurs in north-eastern Myanmar, Vietnam and southeastern China and Hainan Island. It is somewhat darker than the common brown fish owl with a larger tarsus. Its wing chord is {{convert|365|to|457|mm|in|abbr=on}}, with a tail of {{convert|195|to|210|mm|in|abbr=on}} and a tarsus of {{convert|67|to|70|mm|in|abbr=on}}.
==Distribution and habitat== thumb|An adult Brown Fish Owl at Barpeta Assam by Hedayeat Ullah The brown fish owl is an all-year resident throughout most tropical and subtropical parts of the Indian subcontinent to Southeast Asia and adjoining regions. West of its main range, it is patchily distributed to the Levant (possibly extinct) and southern Asia Minor (recently rediscovered). The typical habitat of brown fish owls is forest and woodland bordering streams, lakes or rice fields. It inhabits mainly the lowlands, from open woodland to dense forest as well as in plantations; in the Himalayas foothills it ranges into submontane forest up to {{convert|1500|m|ft|abbr=on}} above mean sea level or so but not higher. It frequently spends the day in stands of bamboo or other large shady trees. They be found around water reservoirs, along canals, on the outskirts of villages and along sea coasts. 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.<ref name = gw9905 /><ref>{{cite journal |last1=Singh |first1=A. P. |year=2002 |title=New and significant records from Dehra Dun valley, lower Garhwal Himalayas, India |journal=Forktail |volume=18 |pages=151–153 |url=http://orientalbirdclub.org/publications/forktail/18pdfs/Singh-DehraDun.pdf |archive-url=https://web.archive.org/web/20080725131900/http://orientalbirdclub.org/publications/forktail/18pdfs/Singh-DehraDun.pdf |archive-date=2008-07-25 }}</ref><ref name= Voous/> Being a large predatory bird, the brown fish owl is only rarely found at a high population density, an exception being Sri Lanka, where this particular owl's adaptability to human habitat change has been beneficial in continued high numbers.<ref name= Mikkola/>
==Behaviour and ecology== [[File:KetupaFoot.png|thumb|left|Foot showing adaptations to catch fish]] The calls of the buffy fish owl are described as a deep humming ''boom-uh-boom'', a ''hup hup hu'' and a loud ''huhuhuhuhuhuhu''.<ref name=HBW2014>{{cite book |author1=del Hoyo, J. |author2=Collar, N. J. |author3=Christie, D. A. |author4=Elliott, A. |author5=Fishpool, L. D. C. |date=2014 |title=Handbook of the Birds of the World and BirdLife International Illustrated Checklist of the Birds of the World |volume=1: Non-passerines |editor=del Hoyo, J. |editor2=Elliott, A. |editor3=Sargatal, J. |editor4=Christie, D. A. |editor5=de Juana, E. |publisher=Lynx Edicions and BirdLife International |location=Barcelona, Spain and Cambridge, UK |chapter=Brown Fish-owl (''Ketupa zeylonensis'') |work=Birds of the World |doi=10.2173/bow.brfowl1.01 |s2cid=216342637 |chapter-url=https://www.hbw.com/species/brown-fish-owl-ketupa-zeylonensis}}</ref><ref name=Grimmett_al2016/> A trisyllabic ''tu-hoo-hoo'' is seemingly the territorial song emitted before breeding. Its call has been described as comparable to that of a distant Eurasian bittern (''Botaurus stellaris'').<ref>{{cite book |author=Harrison, J. |year=2011 |title=A field guide to the birds of Sri Lanka |publisher=Oxford University Press |location=Oxford |edition=Second }}</ref>
The buffy fish owl is nocturnal but can often be located by the small birds that mob it while roosting in a tree. However, in some areas it may be semi-diurnal and has been seen hunting during daytime, especially in cloudy weather. Brown fish owl primarily hunt by stationing itself on a rock overhang or hanging perch over water, or by wading into shallow waters. It grabs food by gliding over the water, nearly skimming it with its feet and grabbing its prey by quickly extending its long legs. It feeds mainly on fishes, frogs and aquatic crustaceans, especially ''Potamon'' crabs. It usually selects the larger freshwater fish available in waterways. Compared to the tawny fish owl, which prefers flowing waters, brown fish owls frequently hunt in still or stagnant waters. By number in the Melghat Tiger Reserve in India, freshwater crabs of the family Gecarcinucidae (of genus ''Barytelphusa'') almost totally dominated the diet.{{citation needed|date=October 2020}} Brown fish owls may be attracted to ornamental fish ponds or commercial fisheries in order to exploit the easily caught fish at such locations. Amniotes, in particular terrestrial ones, are seldom taken. However, other recorded foods have included snakes, lizards, water beetles, other insects, small mammals (including bats) and occasionally water birds. In Melghat, the largest biomass of food consisted of small mammals, namely rats (''Rattus'' ssp.), other types of murids and Asian house shrews (''Suncus murinus'').{{citation needed|date=October 2020}} Birds hunted by brown fish owls have including lesser whistling duck (''Dendrocygna javanica'') and Indian pond heron (''Ardeola grayii''). One unusual prey item recorded was a {{convert|28|cm|in|abbr=on}} long monitor lizard.<ref name= Konig/> Competition may occur between this species and Pallas's fish eagles (''Haliaeetus leucoryphus'') as well as dusky eagle owls (''B. coromandus''), but the brown fish owl is more terrestrial than the fish eagle and consumes more invertebrates than either of those species, the eagle feeding mainly on fish followed by water birds and the eagle owl feeding mainly on mammals followed by land birds. If hungry, brown fish owls will scavenge carrion, a rare behavior for owls. A case where a putrefying crocodile (''Crocodylus'' ssp.) carcass was consumed by this species was observed.<ref name=Voous/><ref name=Konig/><ref name=gw9905 />
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.<ref name=Mourer-Chauviré1986/>
=== Reproduction === thumb|Egg of the brown fish owl Brown fish owls breed from November to April, with activity tending to peak a bit earlier in the north of their breeding range and a bit later in the more tropical south of their breeding range. The breeding season is concurrent with the dry season, which has the benefit of low water levels and thus crabs and fish being more readily assessible. However, most other owls and diurnal raptors also primarily breed in the dry season as well. As owls do not build nest, brown fish owls are somewhat opportunistic when it comes to nesting sites. Brown fish owls frequently nest in shady spots such as old-growth mango trees (''Mangifera'' ssp.), fig trees, including ''Ficus religiosa'' and ''Ficus benghalensis'', ''Shorea robusta'' and other large trees in lowland forests. Outside of the bare surface of large branches, nests are often in spots such as overgrown eroded ravines and steep riverbanks with natural holes. However, it may also nest near suitable villages, along wet roadsides, ''jheels'', canals and rice fields. Usually nest are large natural holes, in hollows or at the base of large branches. Deserted nest built by fish eagles and vultures are also sometimes used as nesting locations. Other nesting sites have included rock ledges, caves in shady cliff faces and stone ruins. The clutch is two or occasionally just one egg. 10 eggs in India averaged {{convert|58.4|x|48.9|mm|in|abbr=on}} in sizes, with eggs of fish owls to the north averaging slightly larger. Incubation is 38 days or somewhat less, and the young fledge after about seven weeks. The downy chicks are mostly an off-white color and develop into a paler version of adults by their second year.<ref name=Voous/><ref name=Konig/><ref name=gw9905 /><ref name=Mikkola/>
== Threats == Apparently in India, during the festival of Diwali, thousands of owls are killed - though programs to counter this practice are underway - including this species due to superstitious beliefs about the evil nature of owls and as an attempt to gain the power of black magic.<ref name=Mikkola/> Habitat destruction will eventually cause the species to desert a region. Due to this, it seems to be extinct as a breeding bird in Israel nowadays, attributable largely to damming practices leading to drying up of many waterways. In Israel, it was decimated by the use of the rodenticide thallium(I) sulfate, which in addition to potential direct exposure through rodents also poisons surface waters.<ref name= Voous/>
==References== {{Reflist}}
===Further reading=== <!-- RevPaleóbiol5:197 --> * Mlíkovský, Jiří (2002): ''Cenozoic Birds of the World, Part 1: Europe''. Ninox Press, Prague. {{Listed Invalid ISBN|80-901105-3-8}} [https://web.archive.org/web/20110520101755/http://www.nm.cz/download/JML-18-2002-CBE.pdf PDF fulltext] * Mourer-Chauviré, Cécile (2004): [Review of ''Cenozoic Birds of the World, Part 1: Europe'']. ''Auk'' '''121''' (2): 623–627. {{doi|10.1642/0004-8038(2004)121[0623:CBOTWP]2.0.CO;2}} [https://web.archive.org/web/20150924062402/http://www.findarticles.com/p/articles/mi_qa3793/is_200404/ai_n9396879 HTML fulltext] * Olsen, Jery; Wink, Michael; Sauer-Gürth, Heidi & Trost, Susan (2002): A new ''Ninox'' owl from Sumba, Indonesia. ''Emu'' '''102''' (3): 223–231. {{doi|10.1071/MU02006}} [https://web.archive.org/web/20090930232448/http://www.uni-heidelberg.de/institute/fak14/ipmb/phazb/pdf-files/2002%20Pdf.Pubwink/17.2002.pdf PDF fulltext] * Pavia, Marco (1999): Un cranio di ''Bubo insularis'' Mourer-Chauviré & Weesie, 1986 (Aves, Strigidae) nelle brecce ossifere del Pleistocene di Capo Figari (Sardegna, Italia) ["A cranium of ''B. insularis'' from the Pleistocene ossiferous breccia of Cape Figari (Sardinia, Italy)"]. ''Atti della Accademia delle Scienze di Torino, Classe di Scienze fisiche, matematiche e naturali'' '''133''': 1–10 [Italian with English abstract]. [http://www2.nrm.se/ve/birds/sape/GlobalOwlProject/Fossil_owls/Pavia%201999.pdf PDF fulltext] {{Webarchive|url=https://web.archive.org/web/20120925034803/http://www2.nrm.se/ve/birds/sape/GlobalOwlProject/Fossil_owls/Pavia%201999.pdf |date=2012-09-25 }} * van den Berg, Arnoud B.; Bekir, Soner; de Knijff, Peter & The Sound Approach (2010): Rediscovery, biology, vocalisations and taxonomy of fish owls in Turkey. ''Dutch Birding'' '''32''': 287–298. [http://www.avibirds.com/pdf/B/Bruine%20Visuil1.pdf PDF fulltext]
==External links== {{Commons category|Ketupa zeylonensis}} *{{cite web |website=World Owl Trust |title=Brown Fish Owl |url=http://www.owls.org/Species/bubo/brown_fish_owl.htm |archive-url=https://web.archive.org/web/20011012200734/http://www.owls.org/Species/bubo/brown_fish_owl.htm |archive-date=2001-10-12 }}
{{Taxonbar|from=Q828255}}
brown fish owl Category:Birds of the Middle East Category:Birds of South Asia Category:Birds of Bangladesh Category:Birds of Indochina Category:Birds of South China brown fish owl brown fish owl