Urinary chemosignals in giant pandas (Ailuropoda melanoleuca): seasonal and developmental effects on signal discrimination

Abstract

As a solitary species, giant pandas Ailuropoda melanoleuca have a chemical communication system that allows for avoidance with conspecifics throughout most of the year and facilitates breeding during their brief reproductive period. To date, most studies have focused on adults during the breeding season, but much remains to be learned about developmental and seasonal effects on chemical communication. Here, using odour discrimination methodology, we examine these contextual influences on chemosignalling in giant pandas for the first time. During the breeding season both adult and subadult giant pandas overtly discriminated conspecific sex using chemical cues in urine. Male urine was consistently investigated more than female urine by pandas across all age–sex categories. This preference for male urine was observed for both adult and subadult urine donors, indicating that adult levels of reproductive hormones are not necessary for the production of sex-specific urinary odour cues. By contrast, giant pandas did not overtly discriminate sex during the non-breeding season. This finding underscores that negative results for discrimination studies need to be interpreted with caution, as many contextual factors may influence overt expression of this ability. Evidence points to seasonal changes in motivation, rather than in the availability of sex-specific chemical cues in urine, as the causal factor for changing odour discrimination patterns. These and other findings are discussed in the light of the potential role that discrimination of odour plays in the regulation of competitive and reproductive interactions in nature.