Fast-breeding tigers are put on the pill

According to Tigger, bouncing is what tigers do best. It appears they are also pretty good at something else.

According to Tigger, bouncing is what tigers do best. It appears they are also pretty good at something else.

The exploding populations of some zoo animals - notably tigers - mean that they are increasingly being put on the pill or given other forms of contraception. And yet the same species are often threatened in the wild.

This apparent paradox is one of the principal subjects of debate at the third congress of European zoo veterinarians in Paris this weekend. The zoo vets will discuss, among other things, the morality - and the best techniques - of preventing tigers, other big cats and some species of monkey and ape from getting pregnant.

Why not just allow the tigers to do what tigers do best and then return the resulting, surplus population to the wild?

The answer is that, increasingly, and where it is appropriate, zoos are doing precisely that. The wild populations of Siberian tigers and tamarind monkeys have been rescued from possible oblivion in recent years by recruits from the world's zoos. "Since the natural habitat of many species is shrinking, zoos play an important role as a kind of Noah's Ark," said Françoise Claro, one of the conference organisers and chief vet at the Paris zoo.

The problem is that zoo populations of some species threaten to grow more rapidly than they can be usefully deployed in the wild. It serves no purpose to release zoo-bred animals into areas where there is limited food for their wild cousins.

Contraception is also needed to prevent sub-species of animals or close relatives from breeding if they occupy the same enclosures.