Why do giant pandas roll around in horse manure?

A team of Chinese scientists spent a decade trying to find the answer to the question that has kept so many of us up at night: why do pandas like to roll around in poop?

Specifically, they had noticed a tendency for giant pandas to smear themselves with horse manure. From The New York Times:

It really is something that the charismatic mammals will do in the Qinling Mountains in China. The bears sniff out fresh horse droppings, lay themselves down and roll their bulky bodies in the muck, using their paws to really make sure they are covered from the tip of their fuzzy ears to the bottom of their tails, until their black and white fur is another shade entirely.


A team of researchers led by Fuwen Wei, a biologist at the Chinese Academy of Sciences, first noticed a panda luxuriating in a pile of horse excrement in 2007. Unsure of whether it was a fluke, they spent years tracking the bears with dozens of camera traps, eventually convincing themselves that the behavior was "definitely frequent and typical," Dr. Wei wrote in an email. Between July 2016 and June 2017 alone, 38 instances were documented, each typically characterized by a series of calculated steps.

Drawn to the irresistible stink of the droppings — the fresher the better — the bears would first take a careful whiff, then initiate a gentle rubbing with a cheek. They would next immerse themselves in an unbridled full-body tussle in the dung, before meticulously slathering themselves with their paws to ensure all their exposed bits were covered.

Plenty of other animals have been recorded fondling feces for a variety of reasons, whether using them to mark their territories or snarfing them as snacks. But it's a bit unusual to pilfer the poop of another species; it's even weirder to lather it up on the regular.

After a decade of research, those scientists have begun to find an answer. But it's still incomplete. As far as they can tell, the pandas are using the horse manure to stay warm — a bear in poop clothing, as it were.

Isaac Chiu, a neuroscientist at Harvard University who wasn't involved in the study, praised the team's molecular work, but added that the sesquiterpenes the researchers found in horse manure can do far more than blunt an animal's ability to sense the cold. Other research has found that these same chemicals might also tamp down inflammation and perception of pain.

Still, it's possible that a patina of poo is just what the bears need to feel cozy.

"Maybe it's like Vicks VapoRub, or maybe like Tiger Balm," Dr. McShea said, describing the tingly feeling they cause.

So why aren't the pandas' own fur coats good enough for the cold weather? We don't know, but it sounds like we're going to need more research.

Why wild giant pandas frequently roll in horse manure [Wenliang Zhou, Shilong Yang, Bowen Li, Yonggang Nie, Anna Luo, Guangping Huang, Xuefeng Liu, Ren Lai, and Fuwen Wei / PNAS]

Why Are Pandas Covering Themselves With Horse Manure? [Katherine J. Wu / New York Times]

Image: Public Domain via Wikimedia Commons