Data from: Density-dependent signaling: an alternative hypothesis on the function of chemical signaling in a non-territorial solitary carnivore

Brown bears are known to use rubbing behavior as a means of chemical
communication, but the function of this signaling is unclear. One
hypothesis that has gained support is that male bears rub to communicate
dominance to other males. We tested the communication of dominance
hypothesis in a low-density brown bear population in southeast British
Columbia. We contrasted rubbing rates for male and female bears during and
after the breeding season using ten years of DNA-mark-recapture data for
643 individuals. Here we demonstrate that male brown bears rub 60% more
during the breeding than the non-breeding season, while female rubbing had
no seasonal trends. Per capita rub rates by males were, on average, 2.7
times higher than females. Our results suggest that the function of
rubbing in the Rocky Mountains may not only be to communicate dominance,
but also to self-advertise for mate attraction. We propose that the role
of chemical communication in this species may be density-dependent, where
the need to self-advertise for mating is inversely related to population
density and communicating for dominance increases with population density.
We suggest that future endeavors to elucidate the function of rubbing
should sample the behavior across a range of population densities using
camera trap and genotypic data.

众所周知，棕熊会通过摩擦行为进行化学通讯（chemical communication），但这类信号传递的功能尚未明确。目前已有一项获得学界支持的假说认为，雄性棕熊通过摩擦行为向其他雄性传递支配地位信号。我们在不列颠哥伦比亚省东南部的低密度棕熊种群中，对该支配地位通讯假说展开了验证。我们借助针对643只个体的十年DNA标记重捕（DNA-mark-recapture）数据，对比了繁殖季与繁殖季后雌雄棕熊的摩擦频次。本研究结果显示，雄性棕熊在繁殖季的摩擦频次较非繁殖季高出60%，而雌性棕熊的摩擦行为则无季节性变化趋势。雄性个体的平均摩擦频次约为雌性的2.7倍。本研究结果表明，落基山脉（Rocky Mountains）地区棕熊的摩擦行为功能或许不仅用于传递支配地位信号，还可用于自我宣传以吸引配偶。我们提出，该物种的化学通讯作用可能具有密度依赖性：即用于交配吸引的自我宣传需求与种群密度呈负相关，而用于传递支配地位的通讯需求则随种群密度升高而增强。我们建议，未来为阐明棕熊摩擦行为的功能，应借助相机陷阱（camera trap）与基因型数据，在不同种群密度梯度下对该行为开展采样研究。