Rival group scent induces changes in dwarf mongoose immediate behaviour and subsequent movement

In many social species, groups of animals defend a shared territory against rival conspecifics. Intruders can be detected from a variety of cues, including faecal deposits, and the strength of response is expected to vary depending on the identity of the rival group. Previous studies examining differences in response to neighbour and stranger groups have focused on the immediate response to the relevant cues. Here, we investigated how simulated intrusions of rival groups affect both immediate responses and post-inspection movement patterns. To do so, we used a faecal translocation experiment at latrine sites within the territories of dwarf mongoose Helogale parvula groups. Immediate responses were adjusted to the level of threat, with greater scent-marking behaviour, time spent at the latrine and group-member participation when groups were presented with faecal matter from out-group rivals relative to control (own-group and herbivore) faeces. Subsequent movement of the group was also affected by threat level, with a decrease in speed and distance covered following simulated intrusions by out-group rivals compared to control conditions. However, there were no significant differences in immediate responses or post-latrine movement patterns when comparing simulated neighbour and stranger intrusions. These results indicate that territorial intrusions can elicit not just an immediate change in behaviour but more far-reaching consequences in terms of movement dynamics. They also raise the possibility that neighbour–stranger discrimination predictions are not necessarily as clear-cut as previously described.