Introduction

Birds of prey that are diurnal, (active during the day) are normally called raptors. This includes eagles, hawks, buzzards, harriers, kites, falcons as well as vultures. Owls are nocturnal (active at night) birds of prey and are sometimes considered to be raptors.

Of the raptors that we will study here the smallest is the Pygmy Falcon which weighs less than a pencil, approximately 60g. The largest is the Martial Eagle, with the adult female having an average wing span of 200 cm and an average weight of 5kg.

There are several fascinating characteristics of raptors, most of them being adaptations to their diet and hunting techniques. This diet varies between species and can include insects, rats and mice, reptiles, including snakes, rodents, meerkats, birds, monkeys and even small antelope. Birds of prey are opportunists and many species will eat carrion when it is available.

ADAPTATIONS OF RAPTORS TO THEIR DIET AND HUNTING TECHNIQUE

Beak and Feet

The beak of a raptor has a particularly awesome and powerful appearance. Most raptors use their beak to rip off pieces of flesh from the body of their prey. Falcons and kestrels, however, use it for killing their prey as well. The powerful and heavily taloned feet of a raptor are the tools that most use to capture and overpower their prey. The sharp talons provide an anchor which the bird needs in order to crush, and kill, its prey. The toes and talons, which are capable of exerting tremendous pressure, are controlled by very strong muscles in the thigh of the bird.

Vision and hearing

Raptors are able to see twice as well as people and are able to detect very small movement from many kilometres away. When hunting they approach their prey at exceptionally high speed, and must be able to adjust the focus of their eyes rapidly. In order to do this birds of prey have well developed muscles controlling the curvature of the lens to be able to focus better.

The hearing of raptors is particularly sharp and most raptors probably use a combination of both their excellent sight and hearing in the pursuit of prey.

Flight

Raptors often fly better, longer, higher, faster and more impressively than any other birds. Within the group; however, wing and tail shape varies according to the hunting strategy of the birds.

Eagles:

With their long and broad wings these birds are very well suited to gliding and soaring. The large surface area of the wings is able to carry the weight of these big birds well.

Goshawks and Sparrowhawks:

These birds have shorter, rounder wings than eagles. They fly by constant flapping and use their longer tails to enable them to twist and turn very rapidly. They are able to make short, fast flights after their prey, which is usually birds.

Falcons:

Falcons are narrow winged and well suited to the high speed flying necessary to catch their fast moving prey. The Peregrine Falcon, a raptor, is the fastest animal in the world, reaching speeds of over 150 km / hour.

THREATS TO RAPTORS

Threat to habitat

Birds of prey in southern Africa are most threatened by the loss of habitat caused by the spread human activity. This means that there is nowhere for the birds to find food or to nest and breed. The Crowned eagle, for example is dependent on forest habitats, eating mainly monkeys, small antelope and dassies living in forests and nesting in the big trees. As forests are destroyed and consequently the habitat of the birds shrinks, so their numbers fall.

Poisoning

Raptors are poisoned both accidentally and on purpose. Stockfarmers, in their desire to rid their farms of problem animals such as jackal and rooikat, will bait a carcass with poison such as strychnine. The raptor, finding the dead animal will feed from it, eat some of the poison and die, even though the farmer may not have intended this.

Direct persecution

Many people still enjoy hunting and shooting birds for sport. Illegal trade in birds does still occur and this involves the capture and removal of a bird from its natural habitat, as well as the robbing of eggs and chicks from nests. In addition birds may be shot because they are thought to be responsible for stock loss. In fact, most often the stock has been killed by some other cause and the raptor has flown in to eat the carrion.

On seeing a raptor on a dead animal, the farmer may conclude that the bird is responsible for its death. In fact very few birds of prey are large enough to injure an animal as large as a lamb for example, let alone kill it. Eye-witness accounts of raptors killing domestic stock are very rare and where they have occurred they have often been as a result of unnatural destruction of the local food source, thus forcing the bird to look elsewhere.

FURTHER READING

Oliver. Jo. - "Our Birds'' A beginners guide to birds. Wildlife Society

Steyn, Peter, The Birds of Prey of southern Africa. David Philip, Cape Town

Butchard, Duncan, 1987. Eagles and Farmers.Endangered Wildlife Trust and SAGS, Johannesburg

Sinclair, Ian and Goode, Douglas 1986. Birds of Prey. Struik Pocket Guides for Southern Africa.

USEFUL ADDRESSES

African Raptor Information Centre, P.O. Box 59507 Karenpark, Pretoria 0118

Endangered Wildlife Trust, Private Bag X11 Parkview, 2122 Tel: (011) 486 1102

The Wildlife Society of Southern Africa. P.O, Box 44189 Linden 2104 Tel: (011) 782 4716

SA Bird Atlas Programme, University of Cape Town, Rondebosch 7700

Southern African Ornithological Society, Head Office P.O. Box 87714 Houghton, Transvaal 2041 Tel: (011) 782 1547