Signalling behaviour is influenced by transient social context in a spontaneously ovulating mammal

Behavioural flexibility may be a mechanism that confers resilience in the face of rapid environmental changes. However, behavioural flexibility is constrained by a number of factors, including physiology. Giant pandas, Ailuropoda melanoleuca, are an endangered ursid found in fragmented habitats at social densities far below their historical carrying capacity. Giant pandas use chemical, visual and acoustic signals to communicate during reproduction. Females are seasonally mono-oestrous, ovulate spontaneously and, thus, fertility and sexual receptivity are temporally constrained. However, because signalling behaviour is energetically costly, the ability to adjust signalling effort according to the presence of an appropriate receiver would be beneficial. Using female giant pandas at the Wolong Breeding Centre in Sichuan, China, we explored the interaction between social context and reproductive status on signalling and maintenance behaviours. To do so, we used linear mixed models and an information-theoretic approach to assess the temporal relationship between signalling behaviours and the timing of first mating. Our results show that signalling behaviour is correlated with time relative to first mating and that multimodal signalling was the best predictor of this timing. Furthermore, we found that social context also influenced signalling behaviours. Specifically, vocal and visual signalling effort were lower in the exclusive presence of other females, reducing the degree of wasted effort. Thus, in spite of the temporal constraints that spontaneous ovulation might impose on sexually proceptive and receptive behaviour, females can modify their behavioural efforts during the preovulatory period according to the prevailing social context. As an iconic endangered species, the giant panda may benefit from research that informs management. Our study provides information that can be applied to increase the success of conservation breeding efforts and their associated reintroduction programmes.