Pandas use scent, feces as form of social networking - study

Scientists reveal that pandas use fecal matter on trees as a form of social networking, according to a study recently published in the peer-reviewed journal Ursus.

Pandas have long been portrayed as solitary beasts. However, a recent study shows that not only do they hang out with family and friends – they’re also big users of social media. Scent-marking trees serve as a panda version of Facebook.

As any dog owner knows, their pets love to smell objects to collect information when taken for a walk. They also mark their scent on trees and walls so they can remember where they have been, and so other dogs can follow them. 

Analyses of animal social networks have traditionally been conducted on species that exhibit social behaviors such as group living, but relatively less work has been done on species that are thought of as solitary, cryptic, and that communicate through scent-marking cues. 

Fecal matter reveals key insights into panda social life  

A recent article in the international journal Ursus under the title “Social network analysis uncovers hidden social complexity in giant pandas” paints a new lifestyle picture of the beloved bears in China’s Wolong Nature Reserve. The lives of these huggable-looking mammals are usually shielded from human eyes because they’re shy, rare, and live in densely forested, remote areas. They use scent marking to keep track of both family members and friends, leave updates about life events, and check out the dating scene.

Lead author Dr. Thomas Connor did this work for his Ph.D. from Michigan State University’s Center for Systems Integration and Sustainability (MSU-CSIS) by spending months hanging out in those forests, watching for signs of pandas since sightings in the wild are much more uncommon. His work was built on previous observations by other MSU-CSIS scientists who suspected pandas likely weren’t the total loners everyone believed them to be.

The researchers used noninvasive fecal genetic sampling, conducted from March 2015 to February 2016, to identify individuals of one such species, the giant panda (Ailuropoda melanoleuca), across a study population in southwestern China.

“Once you’ve gotten an eye for it, you can see on ridge tops and different trails the scent-marking trees, which are stained with a waxy substance – and the pandas seem to be doing this a lot,” Connor said. “It was pretty evident they were exchanging information through scent marking behavior.”

To link the marked trees with an understanding of pandas' social structure, nearby panda communities needed to be documented. To explore that hunch, Connor teamed up with MSU Foundation Sociometrics Prof. Ken Frank, an expert on social networks and a co-author of the article.

The researchers didn’t have a camera on a bear every time it sniffs a tree. “That’s a key part,” Frank said. “I told him that once he has data on which bears are close to each other, we can use the techniques and theories that apply to humans to understand their social networks, and these scent trees are social media. Like Facebook, it’s asynchronous, meaning you don’t have to be in the same place at the same time. It allows one to broadcast to many, and it’s a record. A panda marking a tree isn’t so different from a Facebook post."

To determine which bears were close to each other, Connor dug into a wealth of data he had collected in the form of fresh panda poop. Panda feces are the gold standard of panda watching. What pandas lack in obvious sociability, they make up for in poop production – going some 90 times a day. That means they leave a reliable trail. Connor was able to extract DNA from the fresh panda poop he and his colleagues collected in a 46-square-kilometer area known as the prime panda habitat.

Information from the scat allowed them to identify specific pandas in the vicinity of the scent-marking trees and showed if these pandas were related to each other. That allowed them to combine that with the information from their chosen communication method – the scent trees – to explore their social network.

Pandas socialize in clique-like fashion

“We defined two panda individuals within a certain distance from each other as an association, Connor said. “Even if they’re not directly communicating or running into each other physically, they can exchange information in the chemical scent signature. That built up the social network for the analysis.”

Frank said that once they could determine the bears were in proximity, they could apply the social network technique of community or clique detection. “It’s pretty much like high school,” Frank said. “And like in high school, cliques have lots of implications. There are strong norms within a clique – and while encountering those outside a clique is rare, the information can be very important.”

The scent-marking trees are ripe with information, telling the sniffer who the animal is if they’ve encountered them before. It also tells the marker’s sex, an idea of how dominant and large the bear is, and whether they’re ready to mate.

Connor said the most tantalizing information they gleaned is that in non-mating seasons, the pandas seem to be hanging mostly with other family members – but they seemed to branch out in mating seasons, probably using the scent-marking trees as a territory map.

Connor noted this result was preliminary and limited by small sample sizes but was a tantalizing one that should be studied more. 

“The discoveries in this study shed new light on how pandas use their habitat,” said Jianguo “Jack” Liu, a senior author of the article and CSIS director. “Pandas are a part of coupled human and natural systems where humans share their habitat. Anything we can learn about how they live and what they need can ultimately help inform good conservation policies and maybe understand our own behavior a little more,” he concluded.