Attraction to fecal matter among wild mammals is rare, but Qinling giant pandas have been observed to roll in horse manure. The behavior typically involves a panda sniffing the manure, rubbing against it with the cheek, rolling in the manure, and smearing it over its body. To uncover the purpose of the behavior, Wenliang Zhou, Shilong Yang, Bowen Li, Yonggang Nie, et al. (pp. 32493–32498) observed 38 horse-manure-rolling behaviors in giant pandas from 2016 to 2017. The frequency of manurerolling was correlated with the freshness of the manure and with the ambient air temperature, given that almost all events were recorded at temperatures between -5 °C and 15 °C. Hypothesizing that the presence of the chemical compounds betacaryophyllene and caryophyllene oxide in fresh manure may drive the behavior, the authors found that pandas at the Beijing Zoo in winter preferentially sniffed, rubbed, and smeared hay treated with those compounds. The authors further hypothesized that the compounds may be related to tolerance of cold temperatures and found that mice treated with the compounds exhibited increased cold tolerance. Subsequently, the authors found that beta-caryophyllene and caryophyllene oxide interacted with the pandas’ thermosensitive receptor pathway mediated by the TPRM8 protein and inhibited cold activation of the pathway. According to the authors, manure-rolling may help the pandas acclimatize to cold temperatures. — P.G.
Wenliang Zhou, Shilong Yang, Bowen Li