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　　National treasure– Giant Pandas

　　Giant pandas’Population Survey

　　In order to the population of giant pandas, the third national giant pandas survey began from 1999 to 2003.The results of the survey show that adult giant pandas in China only amount to 1,596.Inearlier investigationsin the 1970s and 1980s, the numbers of pandas were respectively 2,459 and 1,114.

　　Has the number of giant pandas been growing steadily in recent years? Are there any changes in their habitats? This is the most important question that needs to be answered by the fourth giant panda survey. It is generally believed thatwith the improvement of reserve construction and the awareness of ecological protection, the statistics of the fourth survey will be higher than the third one.

　　State Forestry Administration has revealed to the Chengdu Economic Daily that the fourth giant panda surveyreport will be released at the beginning of this month.

　　Gu Xiaodong, Xu Chi, and Zhang Jianwere thrilled at this news. They worked on the fourth giant panda survey (the fourth survey for short) in Sichuan Province. In order to accomplish this report, they began to carried on field investigations from 2011-2013. After one and half years’ expectation, the results would be announced. The members could not help think of those two days when they checked information of giant pandas on the mountains.

　　With snake medicine, the team hiked in the mountains for two years.

　　It’s highly evaluated as "Be responsible for the world and check the number of giant pandas in the wild" by people. However, we wereoften prone to dismiss ourselves as 'pick up the poo poo’ team. Gu Xiaodong, the survey deputy captain, saidthatwild pandas are very vigilant. So it’s lucky to observe a giant panda in the wild. The main work of the survey team is to find wild panda life trails within the designated “line transect." Obviously, the feces are easy to obtain for the study.

　　“Line transect” is the rectangle on the map. Each line transect is roughly two square kilometers. The members had to complete one line transect in a day. "We traveled back and forth in the line transect, taking U or Z glyph, searching for pandas inch-by-inch." said Zhang Jian .

　　In addition to PDAs used in surveys, cameras, vernier calipers, questionnaires, 51 type compasses, snake medicine, enteritis medicine ... These are the regular items that they often brought along with them around 39 panda distribution counties (cities and areas).

　　The Provincial Forestry Department introduced that there were hundreds of people participating in the survey from November 2011 to November 2013. We surveyed an area of more than 2.5 million hectares and there are more than 16000 line transects in this area.In addition to investigating life traces of giant pandas, they also recorded information related to other wild fauna and flora, conservation, regional social and economic conditions, and so on. All the information would be summarized and analyzed to learn more about the latest living conditions, and the result of the fourth giant panda "census" results would be soon to be released soon.

　　Learning from the feces: the "Bamboo Stem Fragment (BSF)" to distinguish pandas

　　How to determine the population of giant pandas? The third survey of the giant panda mainly adopts "BSF".

　　"Giant pandas snap bamboo stems, chew and swallow them. The bamboo stems are discharged through their digestive tract and can almost maintain the original length and shape.These bamboo stems in the feces are known as "BSF."However, it is believed that BSF contains individual marks of giant pandas. Measuring the length of BSF can help distinguish giant pandas." This is the simple introduction about BSF methodin an academic paper by Yin Yufeng and others in the College of Life Science at PekingUniversity .

　　For the survey team, the feces of pandas is quite precious.And the fresher the feces, the rare they are. Giant pandas eat a few kilograms of bambooall day long, which makes a large amount of waste. Pandas’ excrement is like sweet potatoes in shape and size.Because the intestinal tract of pandas is very short, the smell of fresh feces will not only keep the smell of bamboo, but also the complete BSF.

　　The BSF method does not apply to panda cubs as they eat a large amount of bamboo leaves.Thus the third and the fourth survey results were for the number of adult pandas.

　　The survey also introduced a DNA identification method

　　In order to contrast the data with the third survey, the BSF method was used still in the fourth survey. In the mean while, the DNA identification method was introduced into the fourth survey."The requirements for DNA identification from feces are very high. Only fresh feceshad a layer of mucous membrane on the outside," said Zhang Jian. In his two years of field investigation work, seldom did they find any freshfeces.Generally, the feces less than three days can use this method, or the feces in the shade can stay for five days.The feces longer than 5 days can not extract DNA.

　　After we found fresh samples, we would put it into a bottle, soaking with anhydrous ethanol, and the intestinal cells will be broken from the membrane of the feces, making it easy to extract DNA. This bottle will be kept in cold storage, and then transported to the animal research institute of CAS for extraction and research.

　　Uncovering Secrets

　　Through the snow, wading across rivers, good luck is needed to seepandas.

　　The worst thing that annoyed the survey team was the rain and snow duringfield surveys in those two years. It was normal to be soaked to the skin after storm, especially hundreds of people worked in the forests. They felt comfortable when they were back at camp and made a fire to warm themselves.　

　　In order to investigate a specified area, the teammembers often had a lot of hiking to do.The most difficult thing was crossing water. Xu Chi, who had taken part in the survey twice, said when he waded through the river in the valley, if there was no way to go, they had to find the road from other side of the river. One of the members, who went from camp to survey area, had crossed the river nearly a hundred times a day. "In the beginning, people also took off their clothes to cross the river.Afterwards, we didn’t have enough energy to take off our clothes."Said by Zhang Jian .

　　Wearing their wet clothes and going through the snow was normal. The worst thins was that the team members could not go home." The first stage of survey started from March to July and August when the rainy season had arrived every year. Then we started the second stage of survey from September to the end of November. Only in the two adjourns could we go home." Zhang Jian said.

　　"Pandas look clumsy and adorable, but in fact, they are very alert and move quickly in the forests. Their smell and hearing are well-developed. If they detect people, they will hide or escape in no time. " Gu Xiaodong said. Inthe past two years of field investigation, they only met pandas for ten times.