In the heat of the Punjab plain, an Indian zoo is waiting for its collection of lions to die. The males have all been sterilised, to prevent them breeding. Once the Chhatbir zoo had more than 70 lions; today there are 21 left. The problem is that Chhatbir zoo's lions are the result of an experiment in cross-breeding that went horribly wrong.
Looking to devise a special attraction during the eighties, the zoo's administrators created a unique hybrid species by cross-breeding Asiatic and African lions. Less well-known than its African cousin, the Asiatic lion is slightly smaller and has a less shaggy mane. It is close to extinction in the wild: there are only some 300 left, and the only place they are found is the Gir national park in India.
On paper, the cross-breeding programme looked fine. Lions have been successfully cross-bred with tigers, leopards and jaguars - so why not a cross between two natural sub-species? The zoo acquired two performing African lions that were being used in a circus, and bred them with its own two Asiatic lions.
But when their cubs were born, it became clear that all was not well. The hybrid lions were all born with severely weak hind legs. They could barely walk. It got worse: as the years went by, many of the hybrids' immune systems began to fail.
In 2000, when it had bred more than 70 hybrid lions, Chhatbir zoo decided to end the disastrous programme. The males were given vasectomies, and the authorities decided to wait for the hybrids to die naturally.
Today, some of the surviving hybrids are so weak that they cannot even tear meat from bones, and can eat only boneless meat.
With the Asiatic lion so severely endangered in the wild, conservationists have criticised the zoo for "wasting" its breeding programme on creating an unnatural hybrid subspecies. The zoo says that it will turn to breeding pure Asiatic lions, once all the hybrids have died out.
Although there are only 300 left in the wild, the Asiatic lion is in fact one of conservation's success stories. It almost died out completely in the wild: in 1907, there were just 13 animals left. That was when the Nawab of Junagadh, who was then the ruler of one of colonial India's princely states, ordered that they should be given protection within his lands.
The Asiatic lion was once found across a huge swath of the world, from the subcontinent, across Iran and the Arabian peninsula, and even in Europe, in the Balkans. But hunting and human expansion wiped it out everywhere but one corner of India - the Gir forest, the Nawab's old lands, which today lie in Gujarat.
There is a long history of experimental cross-breeding of lions and other big cats. Lions and tigers have been cross-bred to create "ligers", the world's biggest cats, which have faint stripes and small manes.
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