On a mountain in China a giant panda spends hours sitting eating but there is no time for us to sit when trying to understand panda diet.
Recently, we have spent over 3 weeks in the mountains of Sichuan, China searching for giant panda poo, also known as scats, so we can study which plants and animals giant pandas exactly feed on (yes, they do occasionally eat other animals!). We hope to learn more about how the unique relationship between panda and bamboo evolved and how best to manage and restore giant panda habitat.
Giant panda are well known for their highly specialised diet of bamboo and for being very picky about which bamboos they eat. There are as many as 60 bamboos that appear to occur in their habitat, but it is actually very difficult to tell them apart. When you add this with the difficulties of observing pandas in the wild, we may not really know that much about the details of their diet. Plus, we know that occasionally giant panda eat other plants and even animals but we don’t really know how often this happens or why.
The mountains of Sichuan, where most of the wild giant pandas live are spectacular, to say the least, and home to a wide diversity of plants and animals. The steep slopes, and often dense bamboo forests giant panda live in makes them difficult to study. But we don’t actually need to see pandas feeding to know find out what they have been eating, we really only need to look at their scats. By sequencing ‘poo DNA’ we can identify the type of animal the scat came from and what it has been eating.
To do this we look at specific bits of the DNA that are good at telling species apart. These are often known as DNA barcodes. Once we have sequenced these bits of DNA from the scat, we compare them to DNA sequences from plants and animals that have been identified by experts and are usually held within herbaria and museums. When we get a match we know that species was probably eaten by the panda that left the sample. This tells us that not only is that species in the area, but that it is a potentially important food. The specimens within herbaria and museum are critical to making sure that we accurately identify which species are in the scat. This is particularly important in bamboo species, where there is sometimes confusion and different names may be used in different places for the same species.
First, however, you have to find some giant panda scats to study and that is easier said than done.
We spent over 3 weeks climbing and traversing the Sichuan Mountains in search of panda scats, reaching altitudes of 3200m. Scats may be easier to find than a panda but it is still very difficult in the dense bamboo forests on the steep slopes. We negotiated numerous steep, slippery near vertical slopes, river crossings and moss covered bridges (usually 2-3 logs tied together) and of course ploughed through a seemingly endless and almost impenetrable forest of bamboo. At times the bamboo was a welcome change to climbing up the wet, slippery river beds because at least it gives you something to help you climb the steep slopes.
After a week we had seen evidence of giant pandas – paw prints in the mud, chewed leaves and stems of bamboos but still we had not been able to find any scats to collect. By this time we had also seen some of the wide diversity of species that the conservation of the giant panda has helped protect, including takin (a type of goat the size of a cow), golden pheasant, Tibetan macaques (which almost attacked us) and the nests, prints and claw marks of black bears. We even found the scat of a golden leopard cat but no panda scats. Our time was never wasted though, because we were also recording and collecting the many bamboos we came across so we could use them as a reference for comparing to the DNA in the scats and also so we can understand exactly which species occur in giant panda habitat and how bamboos on different mountains and in different mountain ranges are related.
Then, after 10 days in the field on a mountain side at 3100 m above sea level, we found it – the scats from a giant panda only a few days old. By the end of that day we had found 6 samples. We work closely with researchers and the reserve staff in China and with their help we have now been able to locate many more samples. Now there will be many months of hard work in the lab to examine the DNA sequence from both the bamboos we collected and then the panda scats to work out exactly which plants and animals the giant panda feed on.
Dr Linda Neaves, Joint Post-doctoral Researcher - Australian Centre for Wildlife Genomics, AMRI and Royal Botanic Garden Edinburgh.
We thank Tangjiahe, Laghegou and Wanglang Nature Reserves and the China Conservation & Research Center for the Giant Panda for allowing access and for the invaluable help of their staff in the field.
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