for National Geographic News
South Africa's environmental authorities are preparing to wipe out the country's entire population of alien Indian house crows.
The invasive crows arrived about five decades ago and have become such a threat to local bird species that officials say the only option is to kill them all.
"If successful, it will be the first time we have succeeded in eradicating an entire alien species," says Guy Preston, a specialist on invasive species for the South African government and leader of the campaign.
He says the crow, whose home range reaches from Iran to Pakistan and India, is a particularly aggressive species and a scavenger. It kills and drives off other birds until it is the only bird in its range, posing a serious threat to South Africa's biodiversity, Preston added.
The alien bird is smaller than South Africa's native black crow. The house crow keeps to urban and suburban areas, where it tends to nest in buildings and roofs.
The worldwide spread of bird flu has become an additional concern, given the crows' habit of scavenging in chicken coops, preying on eggs and chicks.
"We just have to get on top of them. If we don't, it will have catastrophic consequences for our biodiversity, and it will endanger people because of the diseases they carry," Preston said.
Attempts have been made before to exterminate the birds, but these efforts failed mainly because of a lack of funds.
This time sufficient money has come from the Washington, D.C.-based Global Environmental Facility, the United Nations Development Program, and the South African provincial governments, whose port cities of Durban, Port Elizabeth, and Cape Town have been invaded by the species.
(See map of South Africa.)
"Once we have eradicated [the crows] we'll have to protect our frontiers and monitor shipping to see that they don't come here again," Preston said.
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