Experts at Chester Zoo have helped to save one of the world's rarest bird species from extinction.

Following extensive breeding work carried out with the help of the Zoo, international authorities have taken the Echo Parakeet - native to the tropical island of Mauritius - off the list of species at most danger.

But delight at that remarkable success has been tempered by a new report putting another exotic bird on the list of Critically Endangered species.

China's Blue-crowned Laughingthrush, which Zoo scientists have also been working to help save, is now one of the most threatened wildlife species around the globe.

Scientists at the Zoo have for some years been involved in research into the thrush population and are now increasingly anxious for its survival after new surveys revealed only about 200 remain in remote areas of China.

Unless urgent measures are taken to protect them, they may be wiped out.

The Zoo has previously helped draw up an action plan to guard against any further decline in the bird's population and it has just been involved in talks to renew a deal with the Chinese County Forestry Bureau to limit disturbance to Blue-crowned Laughingthrush breeding sites.

Roger Wilkinson, the Zoo's Head of Conservation, has been to China three times to study the thrush colonies.

He said winning further support from the local people will be vital. Without them conservationists were fighting a losing battle.

"The fact that this thrush was upgraded to Critically Endangered this summer is a sign of just how close to the brink it is," he said.

"There are only a few breeding sites we know of and the potential threats are on the increase all the time."

The birds which were previously found at only two locations - Wuyuan in the rural east of China and Simao near its Vietnamese border in the south are now only known to survive at Wuyuan.

The birds are distinctive for their blue crowns, singling them out from other laughing thrush species.

"They have colonised areas close to human populations and can even be seen in the gardens of local villagers," said Roger, who recently returned from Wuyuan.

"But partly because they are so close to residential areas their habitat is put at increased risk from new road and building projects, as well as deforestation and illegal bird traders."

The Zoo is hoping that success seen from its work with the Echo Parakeet on Mauritius will be matched in protecting the laughing thrush population.

Keepers from the zoo, including husband and wife, Paul and Ann Morris and Clare Daniels, travelled to Mauritius, off the south east African coast, on a mission to help the Mauritius Wildlife Foundation to save the parakeets.

They used their experience of hand-rearing exotic birds at Chester Zoo to help hand rear birds taken from the wild.

Doing this ensured a greater chance of the survival of chicks, which were then released back into the wild to breed, boosting numbers further.

Bird experts first issued an SOS for help in saving the parakeets when it was discovered in the late 1970s and 80s that there were only a handful left in the world.

At one stage their numbers were thought to be as low as six.

But the hard work of conservationists ensured by 2005 those numbers had been boosted to 300.

The latest news that the population was now strong enough for the species to be downgraded from a Critically Endangered' status was a credit to the Chester team and others who worked so hard to secure their future, said Roger.

He said: "It is only due to the public here in Chester and the many families and individuals from around Britain who donate to the Zoo and visit us each year that we are able to finance such vital conservation projects.

"Their support is invaluable in helping us do this kind of work."