The plentiful opportunities to glimpse koalas in the wild are the principal draw, especially for foreign visitors to the island, which lies off the southern coast of South Australia. But few people who leave suffused with a warm glow realise that the furry marsupials are not, in fact, native. Introduced in the 1920s, they are wreaking havoc, stripping their favourite gum trees of leaves and destroying precious habitats.

Conservationists have tried to solve the problem by relocating some koalas to the mainland, and even sterilising them. Now they say there is no alternative but a mass cull. The government agrees - but says that it's out of the question: the country's image would be irrevocably tarnished, it argues, and tourism would go into free fall.