Spotted Eagle-Owl Bubo africanus

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Widespread in the southern half of Africa, the Spotted Eagle-Owl is the most common owl species in many areas. It occurs in a variety of habitats, from rocky outcrops in desert to semi-open woodland, and often occupies areas with a mosaic of low hills, grassland, and scrub, rocky hills with scattered trees and bushes, and thorn savanna, but it avoids dense rainforest. This relatively small eagle-owl is an opportunist forager with a wide variety of prey recorded, taking mainly arthropods, small mammals, and birds. The nest is a shallow scrape, usually on the ground beneath a bush, among grass or rocks, or on an earth bank, but can be on cliff ledge, or on an old raptor or Hamerkop (Scopus umbretta) nest, or Sociable Weaver (Philetairus socius) colony. The Spotted Eagle-Owl ranges from southern Gabon east to southern Democratic Republic of Congo and central Kenya, south to the Cape of South Africa, with a disjunct population (subspecies milesi) in the southern Arabian peninsula. Relative to populations in mainland Africa, subspecies milesi has a very different male (and female) hooting call, and this vocal difference is greater than compared to the formerly conspecific Grayish Eagle-Owl (Bubo cinerascens). Together with other considerations, this has convinced some to treat milesi as a distinct species (1 Collar, N. J., and P. Boesman (2019). The taxonomy of certain Asio and Bubo owl species in Africa and Arabia. Bulletin of the African Bird Club 26: 155–169 Close ).

Length 40–45 cm (2 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second edition. Christopher Helm, London, United Kingdom. Close ); male 490–620 g, female 640–850 g; wingspan 100–113 cm (3 Mikkola, H. (2014). Owls of the World. A Photographic Guide. 2nd edition. Firefly Books, Buffalo, NY, USA. Close ). Rather small eagle-owl with long, erect ear tufts . Facial disc gray with faint white bars, outlined in black; head and neck brown-gray with white to buff spots, including ear tufts; upperparts gray to brown with pale spots, flight feathers and tail broadly banded in buff; whitish below, finely barred gray-brown, upper breast often with large gray blotches; tarsus feathered whitish, faintly barred; irides typically bright yellow (2 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second edition. Christopher Helm, London, United Kingdom. Close ); cere gray; bill black; bare tips of toes dark horn (2 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second edition. Christopher Helm, London, United Kingdom. Close ). In more arid areas rarer chestnut-brown morph, with ground color browner above and buff below, eyes orange. Differs from Cape Eagle-Owl (Bubo capensis) in smaller size, yellow eyes, and grayer plumage. Juvenile washed browner below, less spotted above.

Often considered to include Bubo cinerascens, the Grayish Eagle-Owl, as a subspecies, but the two species differ in morphology and are not known to interbreed where ranges overlap. Taxonomic status of subspecies milesi, significantly isolated in southern Arabia, is uncertain: milesi is more tawny in color and smaller than nominate subspecies and tanae, and its vocalizations differ (see Sounds and Vocal Behavior: Vocalizations). Vocal differences and other considerations have convinced some to treat milesi as a distinct species (1 Collar, N. J., and P. Boesman (2019). The taxonomy of certain Asio and Bubo owl species in Africa and Arabia. Bulletin of the African Bird Club 26: 155–169 Close ). Subspecies tanae perhaps only a pale variant, as is form described from Namibia (trothae). Three subspecies currently recognized.

Widespread in the southern half of Africa, from southern Gabon east to Democratic Republic of Congo (south of rainforest), southern Uganda and central Kenya, south to the Cape region of South Africa. A disjunct population (subspecies milesi) occurs in southwestern Saudi Arabia, Yemen, and Oman.

Occurs in a variety of habitats, from rocky outcrops in desert to woodland with sparse ground cover: often occupies areas with a mosaic of low hills, grassland, and scrub; prefers semi-open woodland, and rocky hills with scattered trees and bushes; also found in thorn savanna and in suburban gardens, such as outskirts of Harare, Zimbabwe (4 Riddell, I. C. (2009). What is the status of the Spotted Eagle Owl in Harare? Honeyguide 55(2): 131–133. Close ); avoids dense rainforest. Occurs from sea-level up to ~2,100 m elevation (2 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second edition. Christopher Helm, London, United Kingdom. Close ).

Generally resident (2 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second edition. Christopher Helm, London, United Kingdom. Close ); local movements in elevation recorded in Malawi, moving to higher elevations during hot summers.

Opportunist, taking mainly arthropods, small mammals, and birds. Large number of different types of prey recorded: arthropods include scorpions, spiders, and beetles; mammals include moles, rodents, hares, hedgehogs, and bats; birds range from sunbirds and doves to falcons, hornbills, and francolins; also reptiles, amphibians, snails, and freshwater crabs (5 Schneider, M. F., and A. A. Jorge (2007). Prey selection of the Barn Owl and the Spotted Eagle-Owl in human-degraded and natural environments in southern Mozambique. Ostrich 78(3): 655–657. Close , 2 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second edition. Christopher Helm, London, United Kingdom. Close ). Diet related to locality and season: in Namib Desert, mainly geckos, gerbils, and moles; in South Africa, 67% of 1,076 prey items were invertebrates; along coast, a pair fed mostly on terns; rodents are major prey when abundant. Prey items (n = 178) identified from photographs of 3 nesting pairs in South Africa consisted of various insects (55.0%; mostly moths and beetles), snakes (19.7%), centipedes (12.4%), frogs (6.7%), rodents (2.8%), geckos (2.2%), a hare (0.6%), and a bat (0.6%) (6 Muller, P. (2016). Finders, eaters. Observations of prey taken by Spotted Eagle-Owls and African Wood Owls. African BirdLife 4(4): 39–47. Close ). Small sample of pellets from South Africa yielded remains of bats, shrews, rodents, birds, and insects (7 Kopij, G., C. T. Symes, and R. Bruyns (2014). Dietary overlap of co-occurring Barn Owl Tyto alba Scopoli and Spotted Eagle-Owl Bubo africanus Temminck in urban and rural environments. Polish Journal of Ecology 62(4): 801–805. Close ). Occasionally eats carrion; regularly drinks water. Crepuscular and nocturnal, rarely diurnal. Hunts from perch, often along roadsides, gliding down on to prey; most prey taken on ground, where often runs after smaller animals; also chases insects, bats and birds aerially.

Vocal Development

Chicks in the nest make cheeping sounds. Outside the nest, juveniles utter a short hoarse hissing note chhhh (note duration ~0.4 s), repeated at intervals (both milesi and africanus). Further vocal development unknown.

Vocal Array

Spotted Eagle-Owl (Arabian) Bubo africanus milesi

Male hoot. A double hoot: first note long, second note at same pitch but short and quavering (duration first hoot 1.43‒1.75 s; total duration double hoot ~4 s).

Female hoot. Not known with certainty. In the case of responding owls, both vocalizations are similar at slightly different pitch (8 Robb, M. (2015). Undiscovered Owls: A Sound Approach Guide. The Sound Approach, Poole, United Kingdom. Close ).

WhUh. A short emphatic hoot (duration ~0.3 s).

Whroohuhuhu. A loose series of soft low-pitched hoots, some slightly longer than others (8 Robb, M. (2015). Undiscovered Owls: A Sound Approach Guide. The Sound Approach, Poole, United Kingdom. Close ).

Spotted Eagle-Owl (Spotted) Bubo africanus africanus/tanae

Male hoot. A double hoot, the second note fainter and lower-pitched whooo..huu (duration first hoot 0.43‒0.74 s; total duration double hoot ~1.6 s) (1 Collar, N. J., and P. Boesman (2019). The taxonomy of certain Asio and Bubo owl species in Africa and Arabia. Bulletin of the African Bird Club 26: 155–169 Close ).

Female hoot. A double hoot, the first one modulated, the second one fainter and lower-pitched whoo-uh..huu. Often as an asynchronous duet given in response to male hooting, and then slightly higher-pitched.

WhUh. A short emphatic hoot (duration ~0.3 s).

Whookokokok. A soft fast series of hoots (9 Fry, C. H., S. Keith, and E. K. Urban, Editors (1988). The Birds of Africa. Volume 3. Parrots to Woodpeckers. Academic Press, London, UK. Close ).

Other. When on nest, male makes a low humming hoorhoorhoor. Female gives humming call that is lower-pitched and has more clucking notes when scraping nest depression, and also utters low clucks when attending chicks (9 Fry, C. H., S. Keith, and E. K. Urban, Editors (1988). The Birds of Africa. Volume 3. Parrots to Woodpeckers. Academic Press, London, UK. Close ).

Geographic Variation

Birds of the Arabian peninsula (subspecies milesi) have a very different male (and female) hooting call compared to birds from the African mainland. Vocal difference is more significant than compared to Grayish Eagle-Owl (Bubo cinerescens). Together with other considerations, this has convinced some to treat milesi as a distinct species (1 Collar, N. J., and P. Boesman (2019). The taxonomy of certain Asio and Bubo owl species in Africa and Arabia. Bulletin of the African Bird Club 26: 155–169 Close ). Voice of subspecies tanae is unknown.

Phenology

In southern Africa, male and female hooting can be heard most of the year. Subspecies milesi has received little attention, but territorial hooting has been recorded in most months.

Daily Pattern of Vocalizing

Especially vocal soon after darkness falls and at pre-dawn, but may call at any time during the night.

Places of Vocalizing

Little documented. Vocalizing birds mainly seen perched on thick branches at mid-level.

Gender Differences

Male and female hooting in subspecies africanus clearly different, and easily identifiable based on first hoot which is disyllabic in the latter case. Other calls not known to be gender specific.

Social Content and Presumed Functions of Vocalizations

Male hooting presumably for territorial defense and mate attraction, and duetting for pair bonding. The short whUh call has been associated with alarm, whereas whookokokok call connected with courtship (9 Fry, C. H., S. Keith, and E. K. Urban, Editors (1988). The Birds of Africa. Volume 3. Parrots to Woodpeckers. Academic Press, London, UK. Close ).

Chicks and adults snap bills, hiss and chitter in threat and distraction displays (9 Fry, C. H., S. Keith, and E. K. Urban, Editors (1988). The Birds of Africa. Volume 3. Parrots to Woodpeckers. Academic Press, London, UK. Close ).

Monogamous, probably pairs for life. Nest a shallow scrape, usually on ground beneath bush, among grass or rocks or on earth bank, but can be on cliff ledge, or on old platform built by Hamerkop (Scopus umbretta), or using Sociable Weaver (Philetairus socius) colony as platform (10 de Swardt, D. H. (2014). Spotted Eagle-Owl nesting on top of Sociable Weaver nest. Ornithological Observations 5: 355–356. Close ); sometimes in hole in tree or building, or old stick nest of diurnal raptor (11 Ewbank, D. A. (2007). Boom & bust: observations on rodent-eating birds in Matabeleland. Honeyguide 53(1–2): 25–27. Close ); same site sometimes used yearly, giving it distinctive odor; traditional sites may be occupied for 30–40 years. Lays in July–February; mainly July–October in South Africa. Clutch 2–4 eggs (range 1–5); mean egg size 49.1 mm × 41.1 mm (2 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second edition. Christopher Helm, London, United Kingdom. Close ); incubation 30–32 days, from first or second egg, by female, fed by male; chick with white down; young brooded and fed by female , male delivers prey usually decapitated; young leave nest at 30–38 days, later if nest above ground, fledge at ~48 days, dependent on parents for at least 5 weeks after fledging , but exact age of independence unknown.

First breeding possibly at 1 year old. Longevity of at least 10 years recorded. Nesting success generally high: at a site in Rwanda, young reared in 14 of 15 seasons; in Zimbabwe, 11 young fledged from 12 eggs; sometimes double-brooded if food abundant.

Numbers

No global population estimate. Little data on population density. In Zimbabwe, ~3 pairs found in 6 km². Fairly common in Tanzania, uncommon in Uganda and Kenya. Widespread throughout southern half of Africa, where often the commonest owl in many habitats.

Trends

No data on population trends, but no indication that numbers are declining significantly (BirdLife International).

Not globally threatened (Least Concern). CITES II. No global population estimate or information on population trend (see Demography and Populations: Population Status). Widespread throughout southern half of Africa, where often the commonest owl species in many habitats. Fairly common in Tanzania, uncommon in Uganda and Kenya.

Sometimes hit by vehicles, may become trapped in barbed-wire fences (or thorn bushes), and drowns in stock tanks or farm ponds (12 Anderson, M. D., A. W. A. Maritz, and E. Oosthuysen (1999) Raptors drowning in farm reservoirs in South Africa. Ostrich 70: 139–144. Close ); other threats include local human persecution.