Why are raptors special?
Raptors are characterized by dramatically curved beaks and claws, powerful wings and superb eyesight, adaptations that contribute to their specialized ecological role as meat-eaters, at the top of the food pyramid. Because of these attributes, raptors are also held in awe as one of the most charismatic groups of birds. Eagles are traditionally a symbol of strength, courage and freedom and appear on many flags, coats-of-arms and emblems. The Peregrine Falcon is able to achieve speeds of over 300 km/hour in its dives, making it the fastest moving animal in the world.
What is the value of raptors in the ecological system?
The diet of various kinds of raptors ranges from locusts, grasshoppers and flying termites to frogs; snakes, lizards, tortoises and other reptiles; fish; game birds and other birds; rats, mice, ground squirrels and other rodents; meerkats, mongooses, hares, dassies (rock hyrax), monkeys and small antelope. The Egyptian Vulture feeds mainly on eggs, whereas the Palm-nut Vulture is mainly an herbivore, feeding on palm-nuts from oil palm trees. Almost all birds of prey feed on carrion.
Large and powerful, eagles control the numbers of small mammals, including pests and problem species such as dassies, hares and rodents that compete with domestic livestock for grazing resources. Verreaux’s Eagles feed mainly on dassies and one pair will catch at least one dassie per day, amounting to 350-400 per year, which equals grazing for 22 sheep. Martial Eagles feed on Helmeted Guineafowl, hares and ground squirrels; and on mongooses and suricates, that have occasionally been implicated in the spread of rabies. Snake-eagles and other eagles eat poisonous snakes of 2-3 m long, including cobras and mambas. Eagles prey on mammalian predators such as jackal and caracal and, together with vultures; help control their populations by competing for the same food sources. Established pairs of eagles are valuable to the farmer because they keep inexperienced solitary birds (that may catch livestock) out of their home range, and prefer natural prey such as hares and dassies to livestock. Lanner Falcons consume large numbers of Red-billed Queleas, whereas other raptors feed on huge numbers of locusts and termites. A Black-shouldered Kite and its mate will catch over 1 800 rodents each year.
Owls are extremely efficient nocturnal predators with well-adapted eyesight and hearing, and mostly hunt rats, mice and insects, controlling these pests in towns and on farms. One pair of Barn Owls with six chicks will catch 30 rodents per night – a total of 3000 prey items in three months.
Throughout the world, vultures have been useful to people for purposes ranging from clairvoyance in Africa to the disposal of human corpses by the Parsees in India. Scavenging raptors, including vultures, Tawny Eagles and Bateleurs, clean the carcasses of both indigenous ungulates and dead livestock, thus alerting farmers to livestock deaths. This rapid disposal of carcasses and afterbirth assists in combating the spread of diseases, such as anthrax, and helps to maintain farm hygiene. Because they can find and consume carcasses very quickly, vultures also control blow-fly infestations on rotting carcasses.
What are the other values of raptors for people?
The presence of birds of prey indicates that the environment is healthy, with a wide and balanced diversity of animal and plant species, adequate ground cover and no poisons. Likewise, a resident pair of Fish Eagles demonstrates the health of a river or wetland. Large birds of prey are especially vulnerable to environmental influences, and changes in their population size can give us early warning regarding the health of the environment.
Southern Africa boasts a wide spectrum of endemic (i.e. not found elsewhere in the world) species including birds. This diversity is associated with a large and lively birding community composed of both professionals and amateurs, with activities from presentations to field outings and photography. Apart from their recreational value, birds are able to attract large numbers of tourists to visit conservation areas and, worldwide, bird watching is one of the fastest growing tourist activities. These growing numbers of birders are boosting the economic importance and value of the subcontinent’s birds, for instance in 1998 the annual economic impact of birds and birding-related activities in South Africa was estimated at R104-R221 million. Much of this money was spent in economically depressed rural areas.
Still need convincing that we need to conserve raptors?
We need raptors to maintain a healthy environment, and their disappearance from an area could ultimately contribute to serious environmental problems. Responsible, sustainable bird-based tourism provides much needed income to people, especially in rural areas, and in turn helps provide incentives for the conservation of raptors and the environment as a whole. Raptors are an integral part of creation and a world without them is difficult to imagine.
General Characteristics of Eagles
Eagles are, in general, large and powerful birds superbly adapted to catch and kill small to medium prey. Eagles have certain adaptations depending on their way of life. For example, those which hunt over open countryside have long, broad wings for soaring while forest dwelling specie have shorter, rounded wings and long tails which enable them to manoeuvre easily between trees.
Adult eagles have very few natural predators and may live for 20 to 30 years. In common with many long-lived animals, they have a very slow breeding rate and an extremely high incidence of mortality among young birds. On average, only 20-30% of young eagles survive their first year and only half of these will eventually reach maturity and raise their own young. This situation is acceptable provided that the adult survival rate remains high. If the balance is disturbed by unnatural mortality factors such as poisoning or shooting, which affects adults and young, the population may exhibit a drastic decline or even disappear.
The presence of a resident pair of eagles in an area is a sure indication of a balanced environment. The eagles cannot survive without their natural prey which is in turn dependent upon sufficient vegetation for food and shelter. The disappearance of birds of prey from an area can ultimately contribute to serious environmental problems.
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