Negative effects of human activity on raptors

For nature the negative impact from human activity can be seriously damaging. Poisons, high voltage power-lines, deforestation and bush encroachment are just some of these activities. Namibia’s large birds of prey have been hard hit over the past couple of months with over one hundred known deaths of eagles and vultures. This number however is not a true reflection of the actual problem as most birds are not found and they will lie dead or dying somewhere in the veld.

The major lethal impact on birds of prey is from the use of pesticides and poisons. These chemicals are commonly used in many ways. sprayed onto crops to kill insects or seed eating birds can totally destroy a food source for small kestrels and falcons. Chemicals can also kill these birds through bioaccumulation, when the chemical builds up to a lethal concentration in the body of an animal eating the chemically contaminated food. Rodenticides that enfeeble a rat or mouse often kill owls and falcons through secondary poisoning.

For our large birds of prey the use of poison (mis)placed to kill mammalian predators such as jackal, leopard or hyena is the most damaging. A single incident can kill scores of birds. Seven species of vulture have been recorded in Namibia with only two of these, the Lappet-faced and the White-backed are commonly seen on farmlands and in the national parks. All are classified as threatened or severely endangered. Almost all of Namibias’ 14 resident eagle species have a threatened to endangered classification. Even though all birds of prey are protected by law Namibia has seen the complete collapse of at least one species, The Cape Vulture.

As the summer rain season approaches Namibia will see the annual influx of 1000s of migrant birds of prey. These visiting birds come in a variety of sizes from 150-gram kestrels to three-kilogram eagles. Some are insect eaters taking especially locusts and many are scavengers keeping the land free of disease and flies. These birds have survived a miraculous journey through Europe and Africa. Together with our resident species they play a vital role in the ecosystem and as a group birds of prey play an increasingly important role in tourism.

Liz Komen
NARREC