How horse manure helps giant pandas tolerate cold

A study finds that giant pandas roll in horse manure to increase their cold tolerance. Qinling giant pandas have been observed to engage with horse manure. The behavior involves a panda sniffing the manure, rubbing against it with its cheek, rolling in the manure, and smearing it over its body. Observed at low temperatures, the behavior's purpose is unknown. Fuwen Wei, Ren Lai, and colleagues observed 38 horse manure rolling behaviors in giant pandas from 2016 to 2017. The frequency of the manure rolling correlated with the freshness of the manure and with the ambient air temperature, as almost all events were recorded at temperatures between -5 and 15 °C.

Hypothesizing that the presence of chemical compounds beta-caryophyllene and caryophyllene oxide in fresh manure may drive the behavior, the authors found that in winter pandas at the Beijing Zoo preferentially sniffed, rubbed, and smeared hay treated with those compounds.

The authors further hypothesized that the compounds may be related to cold temperatures, and found that mice treated with the compounds exhibited increased cold tolerance. Beta-caryophyllene and caryophyllene oxide were then found to interact with the pandas' thermosensitive receptor pathway called TPRM8 and inhibit cold activation of the pathway. According to the authors, manure rolling behavior may help the pandas acclimatize to cold temperatures.