Scientists count on panda droppings in new census
The fourth national survey of wild giant pandas - or rather their dung - has been launched at the Wanglang National Nature Reserve in Mianyang, Sichuan.
The survey is held about once every 10 years. The launch was attended by representatives from the State Forestry Administration, more than 30 national nature reserves and top research institutes such as the Chinese Academy of Sciences, the Mianyang Daily reported.
Giant pandas are rare and unsociable in the wild, with most adults living in solitude for decades. They are also reclusive, leaving behind little trace of their existence in the lush bamboo forest. A noticeable exception is their excrement, with an adult capable of producing more than a dozen kilograms a day.
Since the 1970s, mainland scientists had been using panda dung to estimate the number and distribution of wild giant pandas, counting 1,596 in Sichuan and Shaanxi provinces in the previous survey, completed in 2004. Now, equipped with the latest technology in molecular science, they hope to have a more precise estimate of the population and look into some questions that have long been puzzling them.
For instance, how often do giant pandas have sex in the wild?
Professor Wei Fuwen, chief scientist of the project and deputy director of the Chinese Academy of Sciences' Institute of Zoology, said yesterday that they were testing and refining some new theories, technology and equipment at the Wanglang reserve.
Once they had enough data and experience, they would start the survey in other reserves where giant pandas are believed to exist, either at the end of this year or early next, he said. Wei said scientists' understanding of panda dung deepened with every survey. The first, conducted in the 1970s, used the physical appearance of the droppings to estimate the number of pandas in a forest, based on the belief that the excrement generated by the same animal should be of a similar shape, size and colour. It identified more than 2,400 individuals. In the second survey, in the 1980s, the number dropped to about 1,100 partly because scientists adopted a more precise measurement based on a microscopic finding that the length of bamboo fibre in excrement was unique for each panda due to their chewing habits. But the third survey, based on the finding of animal behaviour experts that a single panda would not defecate further than 500 metres apart in one day, identified almost 1,600 individuals.
Wei said the latest advances in molecular science would enable them to retrieve DNA sequences from panda dung and obtain the most precise estimate of a region's population. But the DNA method will not fully replace the older methods because it costs too much and requires extremely fresh samples.
'Panda dung is a book of knowledge but the most interesting chapter is not about how many there are, but how they live,' Wei said. 'For instance, it can tell us the sexual balance of a clan and how often they mate. It can also tell us whether they have reached the dead-end of evolution with genetic decadence, or if they are adopting new strategies to live with humans.'