OWLS & FARMERS - EWT · Contents Page Page 3 All about owls Page 6 South African Species Page 18...
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OWLS & FARMERS
Page 3 All about owlsPage 6 South African SpeciesPage 18 Threats facing southern African owlsPage 20 Owls and FarmersPage 22 What the public can do to help owlsPage 23 For your information
Published and printed by the Endangered Wildlife Trust 2006. Revised 2012.Printing sponsored Anglo Inyosi Coal
ReferencesBarnes, 2000. Red Data Book of Birds of South Africa, Lesotho and Swaziland.Endangered Wildlife Trust, 2005.Barn Owls and bio-control.Hockey, P.A.R., Dean, W.R.J., Ryan, P.G., 2005. Roberts Birds of Southern Africa. 7th Edition.Konig, C., Woick, F., Becking, J.H. 1999. Owls: A Guide to the Owls of the World. MacLean, G.L., 1993. Roberts Birds of Southern Africa. 6th Edition.Tarboton, W. and Erasmus, R., 1998. Sasol; Owls and Owling in Southern Africa.
All about owlsOwls are one of the most easily recognized bird families, firmly entrenched in folklore and cultural beliefs across the globe. Human views on owls vary from seeing them simply as night-active birds, to being either positive or negative symbols. Owls are not only associated with wisdom and longevity, but also with death, bad luck and evil.
Despite these perceptions, most people have limited knowledge of the fascinating adaptations and indispensable value of these birds. This is largely because of the owls ability to operate after dark, when most people are indoors, or not able to see as well as these nocturnal creatures. Owls have several features that enable them to thrive at night, in particular, acute eyesight, excellent hearing and the ability to fly slowly and silently.
Barn Owls in particular are an asset to the farmer. They raise chicks in an on-going cycle, so at any given time they may have several chicks of different ages in their nest. In this way a pair and their offspring use about 3000 rodents per annum. Measured in terms of rodent food, thats roughly 10 tons of grain saved rather than becoming spoiled or eaten. For farmers who experience excessive rodent infestations, these figureshighlight the importance of choosing a rodenticide product that will not have a negative effect on the owl population!
First published in 2006 Copyright 2006 by the Endangered Wildlife Trust. All rights reserved. The information in this booklet may be used freely but only for non-commercial purposes.Authors: Andr Botha and Hayley KomenRevised 2012: Zelda Hudson, Design & Layout: Marion BurgerRevised 2016: Design & Layout: Marion Burger
ACKNOWLEDGEMENTSA special thank you to Anglo Inyosi Coal for sponsoring the printing of this booklet which will go a long way towards increasing public awareness around the problems facing owls in conservation. Thanks also to Alan and Meg Kemp for reviewing the booklet.
Photographs used in this publication were taken by Andr Botha, Wendy Collinson, Matt Pretorius and Shutterstock.
All about Owls
The forward facing eyes of the owls provide them with binocular vision similar to that of humans. Owls however, have very large eyes, excellent for gathering the limited light available at night, but while a tubular shape reduces their weight, it also limits the birds field of vision. This is compensated for by an owls ability to rotate its neck through up to 270. Owls may also bob and weave their heads when focusing to enhance their three-dimensional view. Each pupil acts independently so that the owls can see objects in shadows and in bright light simultaneously. So, although they do not have x-ray vision, owls certainly see much better than humans do, especially at night.
How well do they hear?
The owls acute hearing has more to do with its ability to pinpoint sound than to detect soft sounds. The part of the brain dealing with hearing is much larger in owls than in most other birds, and owls can detect the direction from where the sound originates very accurately. The owls facial disk reflects sounds towards its ear openings, so further enhancing its hearing. In this way, some owls are able to locate and catch their prey in almost total darkness.
Stealth technology in flight
With the exception of Pels Fishing Owl, all southern African owl species are capable of virtually silent flight. Owls have a large wing surface area compared to body size, while the leading flight feathers have a soft, comb-like edging, allowing them to fly far more quietly than other birds. This talent helps them to better use their acute hearing in flight, and to move in on prey without being heard.
One of the reasons that few people have seen a wild owl is that all species possess excellent camouflage. In addition to cryptically coloured plumage, they roost very quietly and many elongate their bodies to assume the form of a broken branch, further enhancing their camouflage. Species with ear-like tufts will raise these, again improving their camouflage. Despite sometimes perching in exposed places during the day, owls are very difficult to detect.
What does an owl sound like?
Most people associate the typical hooting hu-huuu call of species such as the Spotted Eagle-Owl with all owls. In fact, southern African owls have very distinctive calls that make it possible to identify a species without actually seeing the bird. Calls vary from the high screeching of the Barn Owl to the sharp, repetitive whistle of the little Pearl-spotted Owlet. Owls call to communicate with one another, to find a mate and to advertise their occupancy of a territory. In some species, a pair will call in duet.
All southern African owls lay white, fairly round eggs, different from most other raptors. Owls seem to rely on the camouflage of the incubating parent bird to protect the eggs from detection by predators, especially during the day. At night, the white eggs are easier to detect by the parents when returning from the hunt. Clutch sizes vary from 2-4 eggs, although the Barn Owl can, in seasons of food abundance, lay as many as 19 eggs!
Owls use a variety of nesting sites, ranging from a grassy bowl on the ground in the case of the Grass Owl, to a rocky ledge for the Cape Eagle-Owl, or a natural cavity or hole in a tree for various other species. The Barn Owl shows a preference for man-made structures, such as abandoned buildings or water towers. The smaller, insectivorous owls breed in early summer, while species feeding primarily on rodents breed in winter. Food availability seems to play an important part in determining owls breeding seasons.
Food and feeding
Owls catch their prey with powerful feet and sharp talons. Prey is detected either by sight, hearing, or a combination of the two, and is caught by a quick stoop and drop. Prey vary from insects, other invertebrates, rodents, small reptiles, frogs, crabs, bats and other mammals up to the size of a duiker in the case of the Verreauxs Eagle-Owl. Owls contribute substantially towards controlling rodents and other potentially problematic animals, and are therefore an ally to landowners, in particular grain farmers.
BARN OWL Tyto alba
Afrikaans: Nonnetjie-uil, Tswana: Lerubise, Xhosa: Isikhova, Zulu: umZwelele
Identification: A medium sized owl, above tawny and grey with small white spots. The face and under parts are white with fine brown spots from breast to belly. The brown eyes contrast with the pale heart-shaped face. The longish legs are closely feathered and white.
Voice: At least 15 different calls, but mainly a long thin screeching.
Distribution: All continents except Antarctica, widespread in southern Africa.
Status: Widespread and common.
Habitat: Always near a suitable roost on a cliff or in buildings or trees. Often found in association with man.
Habits: Roosts during the day, usually in pairs. Emerges at dusk to hunt by quartering the ground.
Food: Eats mainly small rodents (75-97% of diet), although in urban areas mainly small birds. Also other small prey such as scorpions, geckos, bats, frogs, lizards and termites.
AFRICAN GRASS-OWL Tyto capensis
Afrikaans: Grasuil, Tswana: Lerubise, Xhosa: Isikhova, Zulu: umShwelele
Identification: Similar to the Barn Owl, but larger and darker above. Below, whitish with a buff breast. The upperparts and under parts contrast strongly. The face is white to pale brown and the eyes are dark brown.
Voice: Usually silent, but when vocal, mostly a series of high clicking notes or a shrill screeching territorial call.
Distribution: Patchily distributed from southern Cape to Ethiopia.
Status: Numbers declining due to habitat destruction. Vulnerable Red Data species in South Africa with fewer than 5 000 estimated to remain.
Habitat: Long grass, usually near water and wetlands.
Habits: Usually found in pairs or family groups of 4-5 birds. Roosts and breeds on the ground in rank grass. Flushes reluctantly, soon dropping back into the grass.
Food: Mostly rodents (76-98% of diet), especially vlei rats, but also birds, reptiles, frogs and insects.
MARSH OWLAsio capensis
Afrikaans: Vlei-uil, Tswana: Lerubise, Xhosa: iNkovane, Zulu: umShwelele
Identification: A medium-sized owl that looks uniform brown from a distance. The facial disc is round and pale brown with a black rim. The creamy white wing bar is distinctive in perching and appears as a pale patch near the wingtips in flight. The owl has ver