There’s a very fine balancing act to be had…. culling – killing using humane methods – one species, to ensure the survival of another
Large mice are devastating rare birds on a tiny island, now moves are afoot to exterminate the rodents. But should conservation ever be about killing? Patrick Barkham explains
Gough Island is about as remote a fragment of land as it is possible to find on a map. Its 91 square kilometres of uninhabited volcanic rock rise from the South Atlantic, 3,200km east of South America and 1,700 miles west of Cape Town. But even this apparently pristine home to 8 million seabirds has been reshaped by humanity. Nineteenth-century seal-hunters visiting the island inadvertently introduced a stowaway: the house mouse. In the years since, this innocuous-looking species, the island’s only mammal, has become its top predator, rapidly evolving to twice its original size.
This monster mouse now eats seabirds alive. Ornithologists first discovered chicks of the endangered Tristan albatross with gaping wounds in 2001. Nocturnal nest cameras revealed the reason: mice clambering in and gnawing and devouring the chicks. Worse, they could even eat adult birds. They also predated thecritically endangered Gough bunting, which is only found on the isolated island. An estimated 2 million fewer seabirds fledge each year because of the mouse.
So the RSPB is leading a painstaking £9.2m operation to eradicate the mice, supported by the Tristan da Cunha authorities as well as the British and South African governments. Forty staff will sail to the island during the southern hemisphere winter of 2021, when the mice are at their hungriest. Poison will be dropped from four helicopters. Around 200 Gough buntings and Gough moorhens will be taken into temporary captivity to reduce the risk of them accidentally eating the poison. The aim is to kill every mouse on Gough Island to help the endangered birds thrive once more.
“Conservationists don’t go into conservation to kill things, clearly,” says Martin Harper, global conservation director of the RSPB. This scheme, the charity’s biggest ever international project, was scrutinised by its ethics committee. The RSPB has come under fire in recent years for predation control. It chooses to protect some rare ground-nesting birds, such as curlews or little terns, by shooting more common animals – foxes and other predators.
New Zealand
Culling methods matter. Jones first saved the pink pigeon from extinction by feeding wild birds and breeding more in captivity, but saw their wild population nosedive again. He realised young birds were being predated by feral cats. When conservationists in New Zealand realised that their unique flightless birds – such as the kiwi and kakapo – were being obliterated by non-native rats, they became the world leaders in culling.
New Zealanders will lead operations on Gough Island. And Jones brought a team of them over to Mauritius. Feral cats were trapped, put in a sack and whacked with a hammer. This method was deemed humane by veterinary surgeons, but local animal rights groups “couldn’t cope with that image,” says Jones. They were aghast. They insisted that the cats were driven to a vet to be euthanised. “The idea of a vet in a white coat and an injection sounds humane, but when you go through the steps, taking them to a vet on bad roads took hours, these wild cats were stressed-out, in a trap, in the heat of the day in a tropical country. That is completely inhumane if you ask me. Killing them with a hammer is far more humane.”
