Body posture, gaze, and predator detection: how stalking behaviour may influence colour vision evolution

The success of a predatory attack is related to how much a predator manages to approach a prey without being detected. Some carnivore mammals use environmental objects as visual obstacles during stalking behaviour, allowing them to get closer to their prey while only showing parts of their coat or faces during movement or visual monitoring. Here, we investigate the influence of carnivores body postures and gaze on their detection by potential prey. To do so, we photographed taxidermized carnivore models (cougar, ocelot and lesser grison) in natural scenes and presented them to human dichromats (i.e., colourblind) and trichromats (i.e., normal colour vision). Our findings highlight the importance of predators complete body outline and gaze as search images during predator detection tasks. We also demonstrate how the coat and facial colour pattern of predators may camouflage their body outline and gaze, hampering predator detection. Furthermore, we observed that carnivore coat colour patterns may serve as an additional cue for trichromats, particularly in hidden carnivore detection tasks that proved to be more difficult for dichromats. We discuss our results within the context of a predator-prey arms race scenario, considering the evolutionary processes that may have generated the evidence presented in this study.