Abstract Animal communication is a key component of animal ecology. In mammals, chemical signalling is the primary channel, though visual and acoustic cues also play important roles. While many studies have explored the seasonality and individual status associated with mammalian marking behaviours, little is known about how conspecific density shapes their occurrence, duration and activity patterns. Here, we tested whether the intensity and temporal dynamics of marking behaviours are density dependent. Using camera traps, we monitored brown bear Ursus arctos marking behaviours (rubbing, pedal marking and tree debarking) at 14 trees across nine mating seasons (2016–2024) in the Cantabrian Mountains, northwestern Spain. Cameras operated continuously (24 h d−1) for 122 monitoring days per tree per year, yielding 1708 tree-days annually and a total of 15 372 tree-days. Our findings reveal that pedal marking, a male-exclusive behaviour, increased in both occurrence and duration with higher conspecific density, suggesting a density-dependent role in mate attraction and dominance signalling. Moreover, all different marking behaviours shifted towards more diurnality as the number of different bears increased. This indicates that bears may adjust their marking activity towards riskier daytime periods in human-modified landscapes, as male–male competition for mates intensifies. Overall, our study provides novel evidence that conspecific density can modulate the intensity and timing of communication behaviours, offering new insights into why brown bears employ a diverse repertoire of marking strategies during the mating period.
Alonso-Resta et al. (Wed,) studied this question.