Detecting a Stalker: The Effect of Body Posture, Gaze Direction, and Camouflage Pattern on Predator Detection.

Abstract

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 (e.g., leaves and branches) as visual obstacles during stalking behavior, allowing them to expose only parts of their bodies while approaching and visual monitoring their prey. Here, we investigate the influence of carnivores' body postures, gaze direction, and camouflage pattern on their detection by prey. To do so, we photographed taxidermized carnivore models (cougar, ocelot, and lesser grison) in their preserved natural habitats and presented these images to human dichromats (i.e., colourblinds) and trichromats (i.e., normal color vision). Our findings highlight the importance of body outline and gaze as search images during predator detection tasks. We also demonstrate that coat and facial color patterns can camouflage predator's body outline and gaze. This is the first behavioral evidence that the facial coloration of natural predators might mask their gaze to potential prey. Furthermore, we observed that carnivore coat color patterns may serve as an additional cue for trichromats, particularly in hidden carnivore detection tasks that proved to be more challenging for dichromats. Our results show possible strategies that evolved between predator and preys, in which prey make use of body outlines, gaze direction, and coat color to improve predator detection, while predators potentially evolved stalking behavior and body/gaze camouflage as counter strategies to cope with the improvements in prey's perception and conceal their presence.