Enviro Facts - Raptors



20) RAPTORS Eagles, hawks, buzzards, harriers, kites, falcons, and owls are all raptors, adapted to hunting medium to large prey animals. Their feet are powerful and heavily taloned for capturing live prey, and their beaks are hooked to tear off pieces of prey. Superb eyesight allows them to spot prey from many kilometres away. Vultures are highly specialised raptors with weak feet and talons, and very strong beaks for tearing meat off the dead animals on which they feed. Adult raptors have few predators and may live for 20 to 30 years. In common with other long-lived species, raptors have a slow breeding rate and a high mortality among young birds. Approximately one-quarter of raptors survive their first year, and only half of these will reach maturity and raise their own young. When adult survival drops as a result of poisoning and hunting, the population of the affected species will be drastically reduced. THREATS TO RAPTORS * Poisoning The use of poisons by stock farmers to kill `problem animals' such as black-backed jackals, caracals, cheetahs or leopards is causing serious declines in scavenging animals (see Enviro Facts "Farmers, poisons and wildlife"). Scavenging raptors that have been affected by this practice include whiteheaded, lappetfaced and Egyptian vultures, and the bateleur. Some poisons, such as organochlorine pesticides, build up in a food chain. A raptor's position at the end of the food chain makes it particularly vulnerable to receiving a large dose. Thus raptors that eat poisoned prey may die, or become unable to breed. Fortunately persistent organochlorines have been banned in South Africa. Owls may be paralysed or killed after eating rodents poisoned by certain rodenticides. Poisoned rats and mice, whether dead or moving slowly as a result of being poisoned, are easier for owls to catch. Thus owls will eat more of these, and accumulate a large dose of poison. Fenthion (used to kill quelea) has, in the past, been incorrectly applied and resulted in widespread deaths of non-target species such as birds of prey and herons. Gamma-BHC was, until recently, used for locust control, and may have contributed to a decline in raptor numbers. It has been replaced by pyrethroid products. * Habitat loss The destruction of raptor habitat through clearing of indigenous forests, bushveld, grasslands and wetlands has contributed to the decline of many raptors. For example, grass owls nest mainly in winter in long grass and vleis. Burning of this habitat during the winter when the chicks are flightless has caused a serious decline in grass owl numbers. With the spread of modern farming, domestic stock replaced herds of game, and their predators, including hyaenas, were eradicated. Vulture numbers dropped as a result of fewer carcasses being available. Without hyaenas to break up the bones of a carcass, there were no calcium rich bone chips for adult vultures to feed their young. Young vultures thus developed a calcium deficiency which resulted in malformed wings making them unable to fly. * Hunting Many people enjoy hunting and shooting raptors for sport, often justified by the belief that these birds kill livestock. In fact, very few birds of prey are large enough to injure an animal as large as a lamb, let alone kill it. Most often the stock is killed by some other cause and a raptor may fly in to eat the carrion. There are very few eye-witness accounts of raptors killing domestic stock. When this does occur, it is often a result of unnatural destruction of the local food source, thus forcing the bird to look elsewhere. * Illegal trading and egg collecting Illegal trade in birds involves the capture and removal of a bird from its natural habitat, as well as the robbing of eggs and chicks from nests. Falcons are particularly vulnerable to this practice as they are much sought after in Saudi Arabia where they are trained for falconry. The illegal practice of egg-collecting has made more of an impact on birds of prey in Europe than in southern Africa. Local species which could be affected by egg-collectors include the very rare taita falcon, found in Zimbabwe, the booted eagle, black eagle, Cape vulture and black sparrowhawk. * Power lines and towers Several raptors perch, roost and nest on electricity towers, sometimes resulting in polluted insulators and an interrupted electricity supply. Occasionally large birds touch two conductors at the same time, or touch one conductor while perched on a structure that is earthed. This will kill the bird and cause an electricity outage. On rare occasions, raptors collide with electricity conductors or the guy wires of telecommunication towers (as used by Telkom and SABC). This is most common amongst young birds learning to fly, or in areas which attract a concentration of birds, such as wetlands. Eskom has addressed these problems by developing insulators and perches to reduce the electrocution threat, markers to reduce collisions, and nesting platforms and insulator shields to protect the electricity supply. * Falconry Falconers need a supply of wild birds to train, thus it is possible that falconry could contribute to a decrease of some species. However, there are very few practising falconers, and they frequently return birds to the wild. Falconry in South Africa is strictly controlled by provincial falconry clubs, in cooperation with provincial conservation authorities. * Disturbance of nesting and roosting sites Some raptors, such as bateleurs, are sensitive to disturbance and will leave their nest, even if they are sitting on eggs or have chicks, if disturbed. DID YOU KNOW? * All raptors are protected by law, i.e. they may not be disturbed, or killed. Shooting of a raptor is allowed only when a permit has been issued, and this happens very rarely. WHAT YOU CAN DO * If you are a farmer experiencing trouble with "vermin" (e.g. caracal, jackal), contact your local nature conservation officer for advice on how to deal with the problem without killing raptors. * Nature conservators can also support farmers in identifying and preserving raptor habitat, and in running a `vulture restaurant'! * Use rodenticides, such as "Racumin", that will not kill owls. * Prevent disturbance of roost and nest sites. FURTHER READING VULTURES AND FARMERS. Vulture Study Group, Johannesburg, 1985. EAGLES AND FARMERS. Endangered Wildlife Trust and SA Ornithological Society, Johannesburg, 1988. PREDATORS AND FARMERS. A. Bowland, M. Mills and D. Lawson. Endangered Wildlife Trust, Johannesburg, 1993. POPULATION ECOLOGY OF RAPTORS. I.Newton, T. & A. Poyser. Calton, UK, 1979. BIRDS OF PREY OF SOUTHERN AFRICA. P. Steyn. David Philip, Cape Town, 1982. BIRDS OF PREY. I. Sinclair and D. Goode. Struik Pocket Guides for Southern Africa, 1986. THE VULTURES OF AFRICA. P. Mundy, D. Butchart, J. Ledger and S. Piper. Acorn Books and Russel Friedman Books, Johannesburg, 1992. All books are available from Russel Friedman Books, PO Box 73, Halfway House 1685. Tel. 011-7022300/1. Enviro facts: "Farmers, poisons and wildlife", "Poisons in the home and garden". USEFUL CONTACTS Endangered Wildlife Trust. P/Bag X11, Parkview 2122. Tel. 011-4861102. Vulture Study Group. PO Box 72334, Parkview, 2122. Tel. 011-646 8617. Poison Working Group. PO Box 15121, Lynne East, 0039. Tel. 012-808 0592. Animal Rehabilitation Centre. PO Box 15121, Lynne East, Pretoria, 0039. Tel. 012-808 1106. Treat and care for poisoned animals. AVCASA. Agricultural and Veterinary Chemicals Association of South Africa. PO Box 1995, Midrand, 1685. Tel. 011-805 2000. Southern African Ornithological Society. Head Office P O Box 87234 Houghton, Transvaal, 2041 Tel. 011-888 4147 Provincial conservation authorities. See telephone book for details.
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