Scientists using DNA samples have doubled their estimates of the wild panda population in a nature sanctuary in China, in a finding they say bodes well for the survival of one of the world's endangered species.

The researchers believe that as few as 66 and as many as 72 pandas may be living in the Wanglang Nature Reserve — more than twice the previous estimate of 32, Wei Fumin, a zoologist at the Chinese Academy of Sciences and a member of the research team, said Wednesday.

The researchers arrived at the estimates by taking samples of panda droppings in the reserve and developing genetic profiles, said Wei.

The rising numbers are likely the result of natural population growth, migration from other areas and the effectiveness of conservation policies such as a logging ban aimed at preserving panda habitat, Wei said.

"We're really seeing these policies start to have an effect," Wei said.

Full results of the research, which was conducted by a joint British-Chinese team, were published in the June 20 edition of the journal Current Biology.

Despite the rising numbers in Wanglang, Wei said it was too early to say whether similar studies in other preserves would show a higher overall number for China's wild panda population, now estimated at about 1,600.

"There could be other factors at work in different places," he said.

Another of the study's authors, Michael Bruford of Cardiff University in Wales, said the environment at Wanglang wasn't significantly different from that at China's other 40 panda sanctuaries, implying there could be many more pandas out there than believed.

And while conservation programs were clearly working, the degree of genetic diversity uncovered at Wanglang seems to indicate panda numbers never fell as low as previously thought, Bruford said.

The authors said they don't expect the findings to dampen China's enthusiasm for assisted breeding, which has proven effective in boosting numbers of captive pandas.

Bruford said the fieldwork carried out by graduate student Zhan Xiangjiang was arduous not only due to the mountainous terrain, but also the need to obtain fresh samples for DNA analysis.

"Once panda feces change from green to brown, we know we've had it," Bruford said.

He said a separate Chinese team had developed the DNA testing method, testifying to Chinese scientists' rising prominence in the field of genetics.

Wei said the new methodology also sheds light on little known aspects of panda life, such as their family ties, geographic dispersal, age distribution and mating and migration habits, Wei said.

Samples taken at Wanglang showed considerable genetic diversity among the panda population, implying robust numbers and considerable migration in and out of the 320-square-kilometer (123-square-mile) preserve high in the mountains of Sichuan province in southwestern China.

"Pandas are very hard to study and there's a lot to be known other than just their population," he said.

Further research using DNA sampling is to be carried out later this year in another key panda preserve in Foping in Shaanxi province to the east of Wanglang, Wei said.