If the island of South Georgia can eradicate rats we should be able to do the same with grey squirrels and urban foxes
On the shores of the Serpentine a tragedy unfolded. A mother duck was shepherding her six newly hatched chicks to the water, while being dive-bombed by crows. Five, four, three, two — despite her frantic clucks and flaps, the predators struck repeatedly. Bystanders hurried to help, but were too late. With her sole surviving duckling only inches from safety, a corvid swooped one more time and we watched helplessly as it carried its prey to its doom, tiny webbed feet flapping, until we lost sight of it high in the trees.
It is a more cheerful story in South Georgia, where an unchecked rat population (introduced through human carelessness) was overwhelming the albatrosses, petrels, prions, pipits and other rare and beautiful species. These ground-nesting birds — there are no trees at those latitudes — are defenceless against these predators, which feast on their eggs and eat the chicks alive. This week a conservation charity reported that a five-year extermination programme had been successful: not a single rodent remains on the island and the bird populations are already rebounding.
The question is not whether we intervene, but how. Scaring away crows from baby ducklings is stressful and inefficient, as I found out last year. Other protection methods work better. Some involve no pain at all: we can build houses with “swift bricks” for crevice-nesting birds. We can make our gardens hedgehog-friendly too — except in the Outer Hebrides, that is, where our snuffly pals are a menace. Since 2002, conservationists have removed some 1,600 hedgehogs from the Scottish isles to protect ground-nesting birds there.
These dilemmas and paradoxes are unavoidable. We successfully exterminated feral cats from St Helena, with the result that rat numbers have mushroomed. We may have to deal with them next. Sometimes our thinking is deeply muddled: probably the biggest threat to our beloved songbirds is the equally beloved domestic cat. Badgers have no natural predators, but we prefer to see them die invisibly of hunger and disease rather than accept any need to cull them.
But we also need a clearer ethical framework. One pillar of this should be to undo or mitigate the damage we have done already. New Zealand is taking a particularly robust stance on invasive species in order to preserve its unique flightless birds. The government there aims to eradicate every rat, stoat, possum and feral cat by 2050. That goes beyond biodiversity: some species are so destructive that they have to be wiped out, not just managed.
The reality is that, as the dominant species on the planet, we are in effect its zoo-keepers. Sitting back and doing nothing is as reckless as opening all the cages and letting the lions eat everything else and then each other, before starving to death. We can run the zoo well or badly, but the responsibility is ours.