Pandas get ready to head off into wild

The number of giant pandas born in captivity in China has now passed the critical threshold that will allow the reintroduction of the species into the wild within three years.

Scientists in China have announced that they now have a stable breeding population of 300 pandas, which has long been considered the minimum number necessary for captive-bred animals to be released back into their natural bamboo-forest habitat, where just 2000 wild pandas are believed to remain.

One of the reasons for the success is that China's main panda-breeding centre in Chengdu, Sichuan, has perfected a technique for boosting the number of twin cubs that survive by tricking mothers into believing they are raising one cub when in fact they are raising two. About 50 per cent of panda births are twins but in nearly all cases the mother abandons one of the cubs at birth.

The Chinese researchers have overcome the problem by rearing the abandoned twin in an incubator and swapping it up to 10 times a day with the other twin so that both cubs are suckled.

The remarkable approach has meant that nearly all twin panda cubs born in captivity are now surviving to adulthood at which point they are enrolled into the breeding pool at the Chengdu centre. By the end of this year, this centre alone will have produced a total of about 140 cubs.

Twin swapping is just one of several techniques that the Chinese scientists have pioneered. Artificial insemination using frozen panda sperm and careful analysis of the female panda's short ovulation cycle have both proved pivotal in the success of the Chengdu Research Base of Giant Panda Breeding, which has funded much of its work by lending pandas to foreign zoos for a fee of US$1 million ($1.3 million) a year.

China has identified three areas of natural bamboo forest in the mountains of Sichuan in southwest China where it plans to begin a careful reintroduction programme of its captive-bred pandas.

The only previous attempt four years ago ended in failure when a solitary male panda that had been freed was attacked, probably by a rival male.

This has led Chinese authorities to take the forthcoming reintroduction far more seriously, with a phased approach over 15 years centred on three reserves at varying altitudes in the Sichuan mountains.

However, critics have argued that a costly reintroduction programme is doomed to fail unless the natural habitat is better protected against human encroachment.

Despite the concerns about habitat conservation, Chinese scientists are convinced that the captive-breeding programme is essential to the long-term future of the giant panda.

Panda pregnancies are notoriously difficult to predict, with births occurring at any time between 11 weeks and 11 months after insemination.

The cub is one nine-hundredth the size of its mother and is born helpless and blind.

TRICK TO GET CUB REARED

The remarkable twin-swapping technique at the Chengdu centre has been captured on film by a British television documentary narrated by Sir David Attenborough.

A pregnant female called Li-Li is filmed giving birth to twins and tenderly cradling her first-born, but ignoring the second cub which has to be put in an incubator.

Keepers are shown distracting Li-Li with a bowl of water and honey and gently swapping the cubs so that each has a chance of being suckled and reared by its mother. Li-Li is unaware that she is raising both of her twins, the keepers say.

The film-makers had full access to the panda-breeding sanctuary and followed the scientists as they tried to prepare males for mating with females, which come into heat for only 72 hours each year.

- INDEPENDENT