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Bubo buboEurasian eagle-owl

By Jessie Cantrell

Ge­o­graphic Range

Eagle owls pri­mar­ily live in the Palearc­tic re­gion, al­though they can travel as far south as the Ori­en­tal Re­gion and Ethiopian Re­gion and as far north as the far reaches of Siberia. They are found in North Africa, Eu­rope, The Mid­dle East, and Asia. ("The Eurasian Eagle Owl", 2002; Konig, et al., 1999; Parry-Jones, 1998; "Eurasian Eagle Owl", 2003)

Habi­tat

These owls can be found in many dif­fer­ent kinds of habi­tats in­clud­ing wooded areas (conif­er­ous forests), warm deserts, moun­tain ranges, and riverbeds. They pre­fer to live in rocky land­scapes, es­pe­cially when nest­ing. Eagle owls search for habi­tats with ad­e­quate food sup­ply and proper nest­ing sites. Their habi­tats vary greatly, and they can also be found in open areas that have few trees like farm­lands and grass­lands. (; "Eurasian Eagle Owl", 2003; "The Eurasian Eagle Owl", 2002)

Phys­i­cal De­scrip­tion

Eagle owls are the largest owls in the world, and they are best known for their large, strik­ing, or­ange eyes. They are often called the Old World ver­sion of Amer­ica's widely dis­trib­uted great horned owl. They have promi­nent ear tufts and are pri­mar­ily brown-black and tawny-buff in color. Their fa­cial disk is heav­ily marked with black, gray, and white. Their upper parts are darker than their lower parts, which have black streaks, and their throat is white. It is in­ter­est­ing to note that these owls be­come paler in the north­east­ern ge­o­graphic re­gions and get pro­gres­sively darker as you move to the Pa­cific coast. Also, size tends to de­crease from north to south, and east to west. ("The Eurasian Eagle Owl", 2002; Konig, et al., 1999; "Eurasian Eagle Owl", 2003; )

  • Sexual Dimorphism
  • female larger
  • Range mass
    1600 to 4200 g
    56.39 to 148.02 oz
  • Average mass
    2800 g
    98.68 oz
  • Range length
    58 to 71 cm
    22.83 to 27.95 in
  • Average length
    65 cm
    25.59 in
  • Range wingspan
    1.5 to 2 m
    4.92 to 6.56 ft

Re­pro­duc­tion

Both sexes are usu­ally soli­tary but they pair up dur­ing courtship. They ad­ver­tise po­ten­tial breed­ing sites by dig­ging a shal­low de­pres­sion into the earth and emit­ting a light stac­cato note and var­i­ous cluck­ing sounds. They also use these calls to keep track of their mate's lo­ca­tion. Peo­ple often hear them call­ing to each other. They keep the same part­ners for life. Eagle owls are very sen­si­tive to their en­vi­ron­ment. If there is not enough food re­sources, will mate at a much slower rate and later into the year. When they have suf­fi­cient habi­tats and plen­ti­ful food, their mat­ing rate in­creases sig­nif­i­cantly. ("The Eurasian Eagle Owl", 2002; Konig, et al., 1999; Parry-Jones, 1998; Pen­te­ri­ani, et al., 2002; "Eurasian Eagle Owl", 2003; )

Eagle owls form pairs in early fall and nest in late Jan­u­ary and early Feb­ru­ary. They pre­fer to nest in crevices be­tween rocks, shel­tered cliff ledges, cave en­trances, as well as aban­doned nests of other large birds. Usu­ally egg lay­ing be­gins in late win­ter. They usu­ally have one batch of eggs per year rang­ing from one to four white eggs. This num­ber de­pends on the food avail­i­able in their area. When the owlets hatch, they are brooded for about two weeks. In about three weeks the young begin to feed and swal­low by them­selves. By week five they can walk around the nest­ing area and begin to fly about 60 days, al­though for only a few me­ters. They leave the nest or are dri­ven out in the fall (Sept-Nov.) Eagle owls are able to breed from the ages of 2-31 years. ("The Eurasian Eagle Owl", 2002; "Eurasian Eagle Owl", 2003; )

  • Breeding interval
    Breeding occurs once a year.
  • Breeding season
    The breeding season lasts from December to April.
  • Range eggs per season
    1 to 4
  • Average eggs per season
    3
  • Range time to hatching
    2 to 3 months
  • Range fledging age
    20 to 24 weeks
  • Range time to independence
    9 to 12 months
  • Range age at sexual or reproductive maturity (female)
    1 to 3 years
  • Range age at sexual or reproductive maturity (male)
    1 to 3 years

Once the eggs are laid, they are in­cu­bated by the fe­male alone. The male kills prey and feeds his mate. Once the eggs hatch, the male con­tin­ues to bring food to the fe­male for the next two weeks. Dur­ing this time the fe­male stays at the nest pro­tect­ing her young from preda­tors and teach­ing them how to eat on their own. All owls are im­printed by their moth­ers, which means they will im­i­tate the first an­i­mal they see. This makes it dif­fi­cult to re­lease owls into cap­tiv­ity if they are not raised by an owl par­ent. If an owl sees a human when they are born, they think they are human too. ("Eurasian Eagle Owl", 2003; "The Eurasian Eagle Owl", 2002; Parry-Jones, 1998)

Lifes­pan/Longevity

Eagle owls have rel­a­tively long life spans once they reach adult­hood. They have no real nat­ural en­e­mies. In the wild, they live for ap­prox­i­mately 20 years, but they can live more than 60 years in cap­tiv­ity. ("The Eurasian Eagle Owl", 2002; Parry-Jones, 1998)

  • Range lifespan
    Status: wild
    68 (high) years
  • Range lifespan
    Status: captivity
    64 (high) years
  • Typical lifespan
    Status: wild
    10 to 20 years
  • Typical lifespan
    Status: captivity
    20 to 60 years

Be­hav­ior

Eagle owls are pri­mar­ily soli­tary an­i­mals ex­cept dur­ing the mat­ing pe­riod. They fiercely de­fend their ter­ri­tory against other owls and will only over­lap ter­ri­to­ries slightly if food is sparce. Eagle owls pre­fer to stay within the same ter­ri­tory un­less they are forced to leave due to food short­ages or if they are dri­ven out by other owls. De­spite their large size, they are very elu­sive crea­tures, which makes them dif­fi­cult to study in their nat­ural habi­tats. Eagle owls spend most of their days roost­ing high in trees re­main­ing rel­a­tively in­ac­tive. They are noc­tur­nal and be­come ac­tive at dusk and re­main so through­out the night. When food is rare, they will hunt dur­ing the day. ("The Eurasian Eagle Owl", 2002; )

  • Range territory size
    15 to 80 km^2
  • Average territory size
    42.5 km^2

Com­mu­ni­ca­tion and Per­cep­tion

Eagle owls are known for their loud calls. They are heard far more than they are seen. They use their var­i­ous hoots and clucks to let oth­ers know they have en­tered or are en­ter­ing cer­tain ter­ri­to­ries. Dif­fer­ent hoots rep­re­sent dif­fer­ent moods and are eas­ily rec­og­niz­able be­tween each mem­ber of the species. Also, eagle owls are able to de­ci­pher the size and dis­tance of in­trud­ers based on the in­ten­sity of their call. They also use a low gut­teral hoot to at­tract mates. It's in­ter­est­ing to note that even though eagle owls are dif­fi­cult to study, they (like other owls) cough up what is known as an owl pel­let after their stom­ach goes through the di­ges­tive process. These owl pel­lets con­tain the hair, feath­ers, and bones of prey they were un­able to di­gest. These pel­lets are very use­ful to sci­en­tists be­cause they help them un­der­stand the food habits of these elu­sive birds. ("The Eurasian Eagle Owl", 2002; Parry-Jones, 1998)

Food Habits

Eagle owls are car­ni­vores. They are pri­mar­ily noc­tur­nal hunters and have var­i­ous hunt­ing tech­niques. They take their prey in flight or on the ground. They pre­fer to hunt in open spa­cious lo­ca­tions rather than forests. Most owls are very ca­pa­ble hunters and the eagle owl is no ex­cep­tion. Owl wings have evolved to make very lit­tle noise when flap­ping. With their night vi­sion, ad­vanced hear­ing, and silent flight they are the hit men of their ter­ri­tory. Their prey usu­ally has no idea they were being stalked. They feed on al­most any­thing they can catch in­clud­ing rats, mice, voles, bee­tles and even large prey like deer fawns and foxes. They will also feed on other birds such as crows, ducks, and even other owls. Dom­i­nant prey can vary from habi­tat to habi­tat but is most often small ro­dents. ("The Eurasian Eagle Owl", 2002; Parry-Jones, 1998)

  • Animal Foods
  • birds
  • mammals
  • reptiles
  • insects

Pre­da­tion

Once eagle owls reach adult­hood, they are at a very low risk of pre­da­tion. They are at the top of the food chain in their niche. They are not a major food source for any other species. The only time they are at risk of pre­da­tion is dur­ing their early years. They are at risk from any preda­tor too large for them too eat. For­tu­nately, the mother stays with the young for most of this pe­riod and keeps the preda­tors at bay. Due to their striped, spot­ted, and var­ied col­or­ing, they are ex­tremely well cam­ou­flaged, es­pe­cially when perch­ing in the trees. (Parry-Jones, 1998)

  • Anti-predator Adaptations
  • cryptic

Ecosys­tem Roles

Eagle owls are at the top of their food chain. They are par­tic­u­larly use­ful in keep­ing the num­ber of ro­dents down in their var­i­ous ecosys­tems. The re­moval of this species can cause the ro­dent pop­u­la­tion in a given area to grow sig­nif­i­cantly. There­fore, they may be a key­stone preda­tor. (Konig, et al., 1999; Parry-Jones, 1998; )

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Eagle owls are eco­nom­i­cally ben­e­fi­cial to farm­ers that want to keep the num­ber of ro­dents down on their land. Many bird­watch­ers will also pay to get a glimpse of this rare bird in its nat­ural habi­tat as well as in zoos. ("The Eurasian Eagle Owl", 2002; "Eurasian Eagle Owl", 2003)

  • Positive Impacts
  • ecotourism
  • research and education
  • controls pest population

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known ad­verse af­fects of the eagle owl on hu­mans.

Con­ser­va­tion Sta­tus

Eagle owls are con­sid­ered rare but not yet threat­ened. Their num­bers are steadily de­clin­ing due to habi­tat loss from human en­croach­ment. ("Eurasian Eagle Owl", 2003)

Con­trib­u­tors

Matthew Wund (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Jessie Cantrell (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Phil Myers (ed­i­tor), Mu­seum of Zo­ol­ogy, Uni­ver­sity of Michi­gan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

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

agricultural

living in landscapes dominated by human agriculture.

arboreal

Referring to an animal that lives in trees; tree-climbing.

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

chemical

uses smells or other chemicals to communicate

cosmopolitan

having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.

crepuscular

active at dawn and dusk

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

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.

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

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

fertilization

union of egg and spermatozoan

forest

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

holarctic

a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.

World Map

Found in northern North America and northern Europe or Asia.

insectivore

An animal that eats mainly insects or spiders.

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).

keystone species

a species whose presence or absence strongly affects populations of other species in that area such that the extirpation of the keystone species in an area will result in the ultimate extirpation of many more species in that area (Example: sea otter).

male parental care

parental care is carried out by males

marsh

marshes are wetland areas often dominated by grasses and reeds.

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

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.

polar

the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sexual

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

solitary

lives alone

suburban

living in residential areas on the outskirts of large cities or towns.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

taiga

Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.

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.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

tundra

A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

Ref­er­ences

The Pere­grine Fund. 2003. "Eurasian Eagle Owl" (On-line). The Pere­grine Fund. Ac­cessed March 21, 2003 at http://​www.​peregrinefund.​org/​Explore_​Raptors/​owls/​eagleowl.​html.

Cen­tre for the Con­ser­va­tion of Spe­cial­ized Species. 2002. "The Eurasian Eagle Owl" (On-line ). The Cen­tre for the Con­ser­va­tion of Spe­cial­ized Species. Ac­cessed 3/21/03 at http://​www.​conservationcentre.​org/​scase21.​html.

Konig, C., J. Beck­ing, F. Weick. 1999. Owls: A Guide to the Owls of the World. New York, NY: Yale Uni­ver­sity Press.

Parry-Jones, J. 1998. Un­der­stand­ing Owls: Bi­ol­ogy, Man­age­ment, Breed­ing, Train­ing. New York, NY: David and Charles.

Pen­te­ri­ani, V., M. Gal­lardo, P. Roche. 2002. Land­scape struc­ture and food sup­ply af­fect eagle owl (Bubo bubo) den­sity and breed­ing per­for­mance: a case of in­tra-pop­u­la­tion het­ero­gene­ity. Jour­nal of Zo­ol­ogy, 257: 365-372.

Woburn Sa­fari Park, "Woburn Sa­fari Park" (On-line ). Amaz­ing An­i­mal Facts. Ac­cessed 3/21/03 at http://​www.​woburnsafari.​co.​uk/​animalfacts.​asp?​aID=11.

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Classification

Classification

  • Kingdom Animalia animals
  • Phylum Chordata chordates
  • Subphylum Vertebrata vertebrates
  • Class Aves birds
  • Order Strigiformes owls
  • Family Strigidae typical owls
  • Genus Bubo eagle-owls and horned owls
  • Species Bubo bubo Eurasian eagle-owl