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Ketupa zeylonensisbrown fish owl(Also: brown fish-owl)

By Madeline Arszulowicz

Geographic Range

Brown fish owls range from the Middle East to Eastern Asia. They occur in deciduous forests that surround bodies of water. In Turkey, they have been seen around the Berke dam and the Antalya region. In Syria, they have been found at the Jambughoda Wildlife Sanctuary. (Vyas, et al., 2013; van den Berg, et al., 2010)

Habitat

Brown fish owls can be found in a range of habitats, including arid deserts, rocky shores, and tropical forests. Regardless of where they live, the presence of bodies of water are essential. Not only does a majority of their food supply live in and around water, but they enjoy bathing in shallow water. In Turkey, they can be found in forested lowlands, close to rivers. (Kirwan, et al., 2008; Mlikovsky, 2003)

Physical Description

Brown fish owls are large, powerful birds of prey with prickly scales on the bottom of their feet. Their claws are large and well curved, with a sharp cutting-edge. The facial disk is indistinct, with long, pointed ear-tufts. The wings are rounded and don’t reach the end of the tail. They are reddish brown and have black or dark brown streaks. The underparts are buff to whitish, with dark streaks and fine brown bars. Their eyes, feet, and beaks are yellow, with their feet being on the paler side while their beak is on the darker side. Juveniles look similar to adults, but are paler. Males tend to be smaller than females in size, which is the only difference between sexes. (Fowler, et al., 2009; van den Berg, et al., 2010)

  • Sexual Dimorphism
  • female larger

Reproduction

Informally, observers and birders have assumed that they mate for life. (Ebbels, 2002)

Brown fish owls breed during the dry season in their home range, when it is easier to find food with low water levels. Pairs of owls will usually take over an old nest found near a body of water, or use a crevice between rocks or trees. The clutch size is either 1 or 2 eggs. (Ebbels, 2002)

  • Breeding season
    November to March
  • Range eggs per season
    1 to 2

Not much is known on the parental care of brown fish owls, other than that they do provide some care to their young, primarily by bringing food to the nest for them. One parent will hunt for food while the other stays close by to watch over the nest. (Ebbels, 2002)

Lifespan/Longevity

Lifespan is not reported in the literature.

Behavior

Little is known about the behavior of these birds. Brown fish owls are residents, staying very close to their nests while hunting. They tend to be nocturnal, but can be semi-diurnal during cloudier days. (van den Berg, et al., 2010)

Communication and Perception

Brown fish owls communicate in duets, with brief breaks between notes. The second note of one will overlap the third note of the other. The second note is slightly higher in pitch, while staying towards the lower end of the pitch spectrum at 135 Hz. Fledglings make a hissing sound to call to their parents. An adult’s song is made up of “huu whoo huu” while juveniles make “keew” calls. (van den Berg, et al., 2010)

  • Other Communication Modes
  • duets

Food Habits

Brown fish owls feed primarily on animals that come from the body of water they live near. They will both perch on rocks or trees near the water and skim the surface once they have seen prey, or they will wade into the water to catch prey. Common prey items include fish, frogs, and aquatic crustaceans, including crabs in the genera Potamon and Barytelphusa, and crayfish. If desperate, they will scavenge carrion. They will also catch rats (Rattus sp.), Indian pond heron (Ardeola gravii), Northern pigtailed macaques (Macaca leonina), and various reptiles. (Jose-Dominguez, et al., 2015; van den Berg, et al., 2010)

  • Animal Foods
  • birds
  • mammals
  • amphibians
  • reptiles
  • fish
  • carrion
  • aquatic crustaceans

Predation

Little research has been done on possible predators for the brown fish owl. The only documented deaths of the species are from humans. Common threats come from use of black magic by locals who will use them as sacrifices and from fish farm workers, who have shot them for feeding on the fish. (Ebbels, 2002)

Ecosystem Roles

No information has been provided on the ecosystem role provided by the brown fish owl.

Economic Importance for Humans: Positive

Local tribes use these birds, along with other owls, as important parts in their spiritual rituals and are thus commonly sold at markets for black magic. (Vyas, et al., 2013)

Economic Importance for Humans: Negative

Due to their diet mainly consisting of fish, the brown fish owl has been caught going after fish at local fish farms, even getting tangled in their nets and fishing lines. (Ebbels, 2002; van den Berg, et al., 2010)

Conservation Status

According to the IUCN, the brown fish owl is labeled as “Least Concern”, due to its large range and stable population size. However, it has been extirpated from Israel and possibly Jordan, Lebanon, and Syria (Hatzofe). In Turkey and most of Europe, it is labeled as Critically Endangered due to dam construction causing changes to their environment and habitat. (Burfield, 2008; Sekercioglu, et al., 2011)

Contributors

Madeline Arszulowicz (author), Northern Michigan University, Alec Lindsay (editor), Northern Michigan University.

Glossary

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

piscivore

an animal that mainly eats fish

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

visual

uses sight to communicate

References

BirdLife International, 2016. Ketupa zeylonensis, Brown Fish-owl. The IUCN Red List of Threatened Species, 2016: 1.

Burfield, I. 2008. The Conservation Status and Trends of Raptors and Owls in Europe. AMBIO, 37: 401-407.

Ebbels, E. 2002. Brown Fish Owl in the Western Palearctic. Dutch Birding, 24-3: 31.

Fowler, D., E. Freedman, J. Scannella. 2009. Predatory Functional Morphology in Raptors: Interdigital Variation in Talon Size is Related to Prey Restraint and Immobilization Technique. PLoS ONE, 4: e7999.

Ghalib, S., A. Jabbar, J. Wind, A. Zehra, D. Abbas. 2008. Avifauna of Hingol National Park, Balochistan. Pakistan Journal of Zoology, 40: 317-330.

Gleich, O., U. Langemann. 2011. Auditory capabilities of birds in relation to the structural diversity of the basilar papilla. Elsevier, 273: 80-88.

Hall, M. 2008. The anatomical relationships between the avian eye, the sclerotic ring: implications for inferring activity patterns in extinct birds. Journal of Anatomy, 212: 781-794.

Hatzofe, O. 2001. "Reintroduction of Raptors to Ramat HaNadiv" (On-line). Accessed April 26, 2018 at https://www.haifa-israel.info/files/Reintroduction_of_Raptors_to_Ramat_HaNadiv.pdf.

Jose-Dominguez, J., N. Ascensio, C. Garcia, M. Huynen, T. Savini. 2015. Exploring the Multiple Functions of Sleeping Sites in Northern Pigtailed Macaques (Macaca leonina). Int J Primatol, 36: 948-966.

Kirwan, G., M. Ozen, B. Demirci. 2008. Turkey Bird Report 2002-06. Sandgrouse, 30: 166.

Kumar, R., G. Shahabuddin. 2005. Effects of biomass extraction on vegetation structure, diversity and composition of forests in Sariska Tiger Reserve, India. Environmental Conservation, 32: 248-259.

Mlikovsky, J. 2003. Brown Fish Owl (Bubo zeylonensis) in Europe: past distribution and taxonomic status. Buteo, 13: 61-65.

Sangster, G., J. Collinson, P. Crochet, A. Knox, D. Parkin, S. Votier. 2013. Taxonomic recommendations for Western Palearctic birds: ninth report. The International Journal of Avian Science, 155: 898-907.

Sekercioglu, C., S. Anderson, E. Akcay, R. Bilgin, O. Can, G. Semiz, C. Tavsanoglu, M. Yokes, A. Soyumert, K. Ipekdal, I. Saglam, M. Yucel, H. Dalfes. 2011. Turkey's globally important biodiversity in crisis. Elsevier, 144: 2752.

Sekercioglu, C., S. Anderson, E. Akcay, R. Bilgin, O. Can, G. Semiz, C. Tavsanoglu, M. Yokes, A. Soyumert, K. Ipekdal, I. Saglam, M. Yucel, H. Dalfes. 2011. Turkey's globally important biodiversity in crisis. Elsevier, 144: 2752-2769.

Vyas, R., K. Upadhayay, M. Patel, R. Bhatt, P. Patel. 2013. Notes of the breeding of the Brown Fish Owl Ketupa zeylonensis. Indian BIRDS, 8: 147.

van den Berg, A., S. Bekir, P. de Knijff. 2010. Rediscovery, biology, vocalisations and taxonomy of fish owls in Turkey. Dutch Birding, 32: 287.

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