Can captive panda cubs help conservation?

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A newborn panda cub and a possible pregnancy are causing excitement among zoo visitors on both sides of the Atlantic.

The blind pink babies, 900 times smaller than their mothers, are striking visual reminders of the vulnerability of the species.

With fewer than 2,500 adults thought to remain in the wild, expectations for the next generation are enormous.

But what difference can captive cubs make to the future of the endangered species?

Zoo-keepers at the Smithsonian National Zoo, Washington DC, are celebrating a new arrival while staff at Edinburgh Zoo are closely monitoring Tian Tian who could be the mother of the first panda born in Britain.

The reproductive difficulties of the animals are numerous and well documented but breakthroughs at breeding centres in China have prompted a relative breeding boom in recent years.

Giant pandas are almost as likely to have twins as they are to have a single cub but seem unable to consistently care for two babies, either in the wild or in captivity.

Experts working to improve the fortunes of the endangered bears have exploited this twin phenomenon, swapping the babies between their mother and an incubator in order to boost their survival rates.

Thanks to genetic matchmaking, artificial insemination and round-the-clock cub care, there are now reportedly more than 350 pandas living in breeding centres around the world.

This success has led to conservationists questioning what the future holds for captive pandas.

"Pandas have lived on our planet for about three million years and the big threat is not really an evolutionary one, it's the fact that their habitat is being destroyed and fragmented," says Heather Sohl, chief adviser for species at WWF-UK.

"The long-term survival of giant pandas in the wild depends on an intact and contiguous bamboo forest and that is currently being threatened by infrastructure development, such as road and railway construction."

Next steps
Habitat restoration and reintroduction are the next big challenges in the panda's plight.

The first concerted reintroduction effort was made when a male panda was kept in increasingly larger semi-wild enclosures until he was finally released in 2006.

Unfortunately, he was found dead after less than a year of living in the wild. Researchers believed he had been beaten by a territorial male and died from injuries thought to have been caused either by the fight or falling from a tree trying to escape.

Prof Michael Bruford from Cardiff University studies the genetic diversity of wild pandas to help guide conservation efforts. For him, environment and experience are key to the animal's future survival.

"There is some indication that translocation of wild born pandas from one site to another might be a more effective approach [than reintroduction]," he said.

"But for captive bred individuals to survive they may need to be raised in far more challenging settings than the average zoo-goer might like to see."

Pandas often live in dangerous terrain, says Prof Bruford, and so need to gain experience of the kind of challenges posed by, for example, cliffs and trees.

"They climb trees a lot and some small trees at that. They are perfectly adapted to do this but won't experience the smaller branches and more difficult climbs in captivity and they certainly won't be used to falling," he said.

Trying again
In 2010, scientists began their second attempt at wild reintroduction, selecting pandas from the breeding programme that were suited to wild living.

Four pregnant pandas were transferred to the "wild training base" and a cub - Tao Tao - was born and raised with little human intervention.

Last year, when Tao Tao was old enough to leave his mother, he was released into Liziping Nature Reserve at Shimian County in Sichuan Province where he now lives, tracked by a GPS collar.

More pandas from the reintroduction programme are due to be released this autumn and next spring into suitable areas where few pandas currently reside.

International zoos that care for pandas must return any young to China at two years of age but despite this caveat, the chances of pandas born outside of China currently making it back into the wild are slim.

For now the legacy of these captive cubs remains in research as they inform scientists on the best methods to care for future generations.

In the face of arguments that the charismatic yet complex creatures are "undeserving" of such costly conservation, Iain Valentine, director of Edinburgh Zoo's giant panda programme, argues that they inspire investment in the natural world.

"Panda conservation work needs to be held up as a great example of what can be done in terms of the conservation of a species. It's holistic, it's embracing all of the issues and it's working," he told BBC Nature.