Derivation of scientific name
Bubo is the genus name for the Eagle-Owls, including the Eurasian Eagle Owl (Bubo bubo). The name was probably derived from the owl’s call ‘uhu’ and is an ancient name that was borrowed into many languages. The species name, africanus, means ‘from or of Africa’, where this species occurs.
Gevlekte ooruil (Afr.); ifubesi, isihulu-hulu (Xhosa); isiKhovampondo (Zulu); makhohlo, morubisi, sehihi, sephooko (South Sotho); sikhova (Swazi); xiyinha (Tsonga); makgotlwê, mophoê, morubise (Tswana).
How to recognise a Spotted Eagle-Owl
A large grey owl, 43–50 cm tall, barred in front and blotched on the head, back and wings. Their wingspan is about 1 m. The distinguishing features of the Spotted Eagle-Owl are the prominent tufts of feathers on either side of its head, which it erects into ‘ears’ or ‘horns’, and its bright yellow eyes. The ear tufts are for show and have nothing to do with their ears or hearing. The sexes are alike in colour and size, and the juveniles resemble the adult. Their plumage can be fairly varied, and there is a rare rufous colour form, which is reddish brown, more heavily blotched and has orange eyes. The Spotted Eagle-Owl can be confused with the Cape Eagle-Owl (Bubo capensis).
The Cape Eagle-Owl is a larger bird, 48–54 cm, although it is still not easy to distinguish them on size alone, especially in the field. It is a rufous-brown rather than grey and has orange eyes rather than yellow, but it is not easily distinguished from the rufous form of the Spotted Eagle-Owl. The surest way to distinguish these two owls is to look at their breasts. That of the Spotted Eagle-Owl has fine barring, while the Cape Eagle-Owl has black and chestnut blotching.
Spotted Eagle-Owls are nocturnal. They roost during the day, either in trees or among rocks. At sunset they fly out to a perch to hunt. From the perch they scan the ground for movement, using both their eyes and ears to detect it, flying silently in pursuit of whatever suitable prey they see. While roosting they make themselves as inconspicuous as possible, drawing their feathers tightly to their body and closing their eyes to hide any telltale glint and sitting dead still. At dusk they are quite conspicuous, perched in prominent positions and calling.
The call of the Spotted Eagle-Owls is a mellow hoot. The males usually give a double hoot, ‘hoo-hooooee’, which the female answers with a softer triple hoot, ‘hoo-hoo-hooee’. If you happen to be watching one while it is calling, you will see a white patch on its throat become briefly conspicuous at each hoot. They are most vocal in the months leading up to the breeding season, May to August. Owls call to find partners, to tell their partners where they are and to proclaim their territories.
The chicks call for food with a loud screech-like hiss. The chicks hiss and click their beaks if they feel threatened. Chicks that wander far from the nest and appear to be lost are easily located by their parents by their wheezing call. The chicks only hoot once they are mature. While breeding, the parents will hiss and make snapping or clicking sounds with their beaks when they feel threatened, e.g. when people come too close to the nest. They may also put their head down and spread their wings out sideways to intimidate whatever they feel threatened by. They can become aggressive and attack to defend their nest, flying at people and/or dogs and scratching them with their talons.
The Spotted Eagle-Owl is resident throughout southern Africa, where it is the most common large owl. Its range extends across sub-Equatorial Africa to southern Arabia.
The Spotted Eagle-Owl is found in a variety of habitats, including open scrub, grassland, savanna woodland, forest patches and forest edges, but not in evergreen forest or sandy deserts. An owl pair has a territory. Their nesting site will be about 0.5–2.5 km away from the nesting site of any other owls, in suitable habitat. The male claims the territory with his hooting call. They are adaptable and not fussy about where they nest or what they eat, which has made them a successful, widespread species.
They nest in many different places, most commonly on the ground, among rocks on rocky hillsides and koppies, under shrubs, in trees, tree hollows, tree stumps, cliff ledges, quarries or eroded banks of a donga or river, in haystacks and in the abandoned nests of other birds. They roost in trees, among rocks, in rock crevices, on sheltered cliff ledges, under bushes or in high grass, in the abandoned burrows of other animals.
The Spotted Eagle-Owl has adapted to living with people and is found in towns and cities, as long as there are gardens and parks where they can hunt and they can find places to roost, undisturbed, during the day. They nest on or in buildings, on window ledges or window boxes, or in owl boxes provided by people, and use streetlights and telephone poles as perches.
Where Spotted Eagle-Owls find a successful nesting spot, they typically use that same site year after year, sometimes for decades. At Kirstenbosch, a pair used to nest in the Camphor Avenue every year until one of the pair was killed. There is now a pair that nests just above the Cycad Amphitheatre in the same spot every year but one since about 2006. Their nest is in a hollow in a large rock in front of a tree at a very busy intersection where tractors, shuttle cars and many people pass by daily.
It is suspected that the female likes this nest because nothing can creep on her from behind, nobody can stumble into the nest, and she can see out very well yet she is not easily spotted from outside. The nest is just above average human eye level and people tend not to see her unless they know where to look. Visitors and tour guides have spread the word and this owl pair and their offspring have become quite famous and are possibly the most photographed owls in the world.
Spotted Eagle-Owls have a varied diet. The type of food they eat depends largely on their habitat and what is available to them. They hunt at dusk and at night, rarely during the day. They prey on insects such as crickets and large beetles, small mammals such as shrews, mice, rats, squirrels and mole-rats, and birds up to the size of a Laughing Dove, including Cape Spurfowl (Francolin) and Helmeted Guineafowl chicks. Frogs, lizards and snakes, and carrion are also eaten.
They hunt from perches and will use any feature of the landscape that gives them a good vantage point, such as trees or rocky ridges, as well as telephone poles, streetlights, pylons, walls, chimneys and the garden’s signage. When an owl sees prey, it swoops down and pounces on it, either taking it back to the perch or to a flat area to eat. They can also catch insects and birds in flight. Since many owls, particularly the immature ones, choose a road as their hunting and eating grounds, many of them get hit and are killed by cars.
Smaller prey may be swallowed whole, but larger prey is dismembered and eaten in bites. Owls don’t have a crop. The food passes directly to the stomach where it is digested and the indigestible portion is compacted into a pellet. This ball of hair and bones is regurgitated (spat out) 6–12 hours after eating. The pellets contain fragments of bones and skulls of their last few meals and are dropped below their roosting and nesting sites. Scientists use the pellets to identify the prey the owls are catching.
SEX and LIFE CYCLES
Sex: Spotted Eagle-Owls form life-long pair bonds. They don’t build a nest, but use a suitable site. Eggs are laid in late winter to spring in southern Africa (August to October). They rarely raise more than one brood. There are 2–4 eggs in one clutch, laid at intervals of 2–3 days. Rarely as many as five or six eggs are laid in a year of prey abundance. The eggs are rounded and white. The female incubates the eggs and the male brings food to the nest for her. She leaves the nest a few times briefly at night to receive the food. Eggs hatch after 32–34 days. There are usually two chicks in one brood, occasionally three and rarely four. The Kirstenbosch pair raises two chicks every year, but occasionally there has been only one. Both parents rear the chicks.
Family life: Chicks hatch at intervals and show no aggression to their siblings. Newly hatched chicks are covered in white down. Their eyes are closed during their first week. After the second week they have a thicker second coat of greyish down and the first feathers start to emerge. The female rarely leaves the nest during the first two weeks, with the male owl providing all the food. From the third week, the female spends less time in the nest and starts to help the male with the hunting.
Even though she is not always in the nest anymore, she is never far from her chicks and is always on guard and will swoop down on anything that threatens them. The chicks can stand when they are three weeks old and become more active and adventurous and start to wander around the nest site. The chicks leave the nest when they are about six weeks old, but they are not yet able to fly. Their wing feathers are well grown, their tail feathers are about half the final length and there is still some down on their underparts and heads.
They are able to fly and catch their own prey when they are seven weeks old. After they have left the nest, the chicks remain in the vicinity of the nest site and their parents continue to feed them until they can fend for themselves. They remain a tight family unit, and at Kirstenbosch, the chicks and their parents are seen roosting together in the trees during the day well into the summer months. They are only fully independent when they are about four months old, and around this time the young owls move away from their parent’s territory to find a territory of their own.
Young owls may move a few dozen or a few hundred kilometres away from their birthplace before they find a territory of their own to settle in. The owls are mature at one year old and these birds can live for 11–12 years.
THE BIG PICTURE
Friends and Foes
Owls are predators and don’t have many natural enemies. Most creatures that try to take an owl chick or an immature owl, like a snake, mongoose or caracal, run the risk of being killed or injured by the parent. Their only real predator is the Martial Eagle and mankind. People kill owls out of fear, or for superstitious reasons, or accidentally hit them with cars. People also collect their eggs, and poison rats – leading to secondary poisoning when the owls eat the poisoned rats. Domestic dogs and cats are known to kill chicks.
Spotted Eagle-Owls will aggressively defend their territory from other owls, mostly young owls trying to move in. They will also aggressively defend their nest and chicks. Wild and rural owls will hide or retreat from people and watch them approach. Sometimes the female may feign injury to distract attention from the nest or chicks. Owls that have become habituated to humans generally don’t fly off when approached by people, but will attack the intruder if it approaches too closely. They fly at the intruder, sometimes scratching them with their talons. The Kirstenbosch breeding pair has become very accustomed to people and allow them to get very close to the nest and to the chicks. They have not ever, to the author’s knowledge, scratched a visitor, although there have been reports that the male has flown at people who get too close to the nesting female.
Spotted Eagle-Owls have acute hearing, enabling them to pinpoint the tiniest of sounds. Their faces are shaped in such a way that it reflects the sounds towards their ear openings so that the sound is amplified. They can catch prey in almost total darkness, purely from following the sound.
They have very large eyes and excellent vision, and are able to see at night. Their pupils act independently of each other, which allow them to see something that is in bright light and in shadow at the same time. Owls have forward-facing eyes and binocular vision, but this also means that they have a narrow field of vision, and to overcome this, owls have evolved a very flexible neck that can twist around to 270 degrees. They can swivel their heads to look behind them without moving their body. They are farsighted and cannot focus on things very close to their eyes. If you ever see one bob its head up and down or from side-to-side while looking at you, it is trying to get a clearer, three-dimensional picture of you. It is also interesting to note that owls’ eyes don’t reflect in torch light.
The surface area of their wings is large in comparison with their body size, and their feathers have a soft, comb-like edging. This gives them the ability to fly silently, allowing them to ambush unsuspecting prey, and also to be able to hear while flying in pursuit of the prey. They are also able to fly quite slowly.
Spotted Eagle-Owls are very difficult to detect during the day. The colours and patterns of their plumage camouflage them, allowing them to blend in to their environment, and they roost very quietly and keep very still. They sometimes get mobbed by agitated smaller birds, which give away their position. At Kirstenbosch, when they are not in their familiar breeding spot, a way to find which trees they are roosting in for the day is to look for their telltale white droppings and pellets on the floor underneath, although take note that not all white droppings are owl droppings.
The conspicuous ear tufts of eagle-owls give them their characteristic silhouette, but have nothing to do with the owl’s hearing. They are thought to aid the owl’s camouflage while roosting by breaking up its outline and helping it blend into its surroundings. They could also mimic the facial patterns of potential predators, such as caracal, causing the ‘look-a-like’ predator to withdraw in the event of a face-to-face encounter.
Owls have large, powerful feet and sharp talons that they use to catch and kill their prey by crushing its skull or body. The beak is short and hooked with sharp edges, and is designed for gripping and tearing its prey.
Poorer world without me
Spotted Eagle-Owls are predators of pest species, such as rats, and encouraging owls is a natural way of reducing rat populations. Since they also eat insects, they keep the numbers of other potential pests, like grasshoppers and crickets, in check too. Fewer owls mean more rats.
People & I
Owls are very recognisable and have many stories, myths and beliefs around them. They are associated with wisdom and learning, as well as with death, evil and bad luck.
People all over the world fear owls and believe that they are bad omens that will bring death, illness or bad luck. They are also believed to have magical powers, and in some places, they are killed and used to make traditional potions in the belief that some of the owl’s ‘magic’ will be transferred to the person using the potion. Owls also make regular appearances in scary ghost or haunted house stories and horror movies. Their large staring eyes, ‘horns’ and haunting call are additional reasons why people fear them. Also because they are active and effective hunters at night and humans tend to be scared of the dark. Owls are also revered and associated with wisdom. The owl is the sacred bird of Athena, the ancient Greek goddess of wisdom and night.
Conservation status and what the future holds
The Spotted Eagle-Owl is not threatened and is common and widespread. Although these owls are quite capable of looking after themselves and have adapted to many human-altered landscapes, too many owls die unnecessarily due to human action. They die from eating poisoned rats. They are killed by cars on the roads at night. They fly into strands of barbed wire on fences. Chicks are killed by domestic dogs and cats, and owls are killed or hurt by people that fear them or use their body parts in traditional medicine.
People can help by not poisoning rats with pesticides that will also harm or kill the owls that eat the poisoned rats. Slow down when driving at night and be alert to the possibility of hitting an owl on the road. Spread the word to those who have a fear of owls that they are harmless and useful friends to mankind, as they can help keep the rat and insect populations in check. If there are no owls in your neighbourhood, it may be because the habitat is unsuitable, or because there are no suitable nest sites for them. In the latter case, people willing and able to host an owl family in their garden can build or buy a nesting box suitable for Spotted Eagle-Owls.
The Spotted Eagle-Owl and all species in the Strigiformes, except the few that are on Appendix 1, are listed on CITES Appendix 2. International trade, with or without the exchange of money, in these species is controlled and export permits are required.
The Spotted Eagle-Owl belongs in the Strigidae, the family of typical owls, in the Strigiformes, the order of owls and nightjars. The other typical owls in southern African are the Marsh Owl (Asio capensis), Cape Eagle-Owl (Bubo capensis), Verreaux’s Eagle-Owl (Bubo lacteus), African Barred Owlet (Glaucidium capense), Pearl-spotted Owlet (Glaucidium perlatum), African Scops-Owl (Otus senegalensis), Southern White-faced Owl (Ptilopsis granti), Pel’s Fishing Owl (Scotopelia peli) and the African Wood Owl (Strix woodfordii). Only two other owls also occur at Kirstenbosch in the wild areas of the estate; the Cape Eagle Owl in rocky areas on the mountain and the Wood Owl in the forest.
Species: B. africanus (Temminck, 1821)
References and further reading
- Ginn, P.S., McIlleron, W.G. & Milstein, P. le S. Compilers, 1989. The Complete Book of Southern African Birds. Struik Winchester.
- Sinclair, I., Hockey, P. & Tarboton, W. 2002. Sasol Birds of Southern Africa, third edition. Struik.
- Steyn, P. 2009. A Delight of Owls: African Owls Observed. Jacana Media.
- Steyn, P. 2012. Spotted Eagle Owl fact file, an extract from an article in Promerops No 292, November 2012, http://www.capebirdclub.org.za/articles-promerops%20nov%202012%20peter%20steyn.html accessed 11 September.
- Tarboton, W. & Erasmus, R. 1998. Owls and Owling in southern Africa. Struik.
- Tarboton, W. 2001. A Guide to the Nests and Eggs of Southern African Birds. Struik.
- Biodiversity Explorer, http://www.biodiversityexplorer.org/birds/strigidae/bubo_africanus.htm. Accessed 11 September 2014.
- CITES Appendices I, II and III http://www.cites.org/eng/app/appendices.php. Accessed 12 Sep 2014.
- Owls and Farmers. Endangered Wildlife Trust (booklet). 2006. http://www.ewt.org.za/eBooks/booklets/Owl%20booklet.pdf.
- Wiktionary, http://en.wiktionary.org/wiki/bubo. Accessed 12 September 2014.
Author: Alice Notten
Kirstenbosch National Botanical Garden