Beware of my face: The role of facial configuration in predator recognition

The important role of facial elements (hooked beak and conspicuous eye colour) in the recognition of avian predators has been repeatedly demonstrated. However, no attention has yet been paid to the importance of their canonical configuration i.e., the relative position of the eyes and beak. In our study, we tested the ability of untrained wild tits to recognise a dangerous predator (a sparrowhawk) with inverted eye and beak positions (invert dummy) and with one eye above and one below the beak (inline dummy) in aviary experiments. A dummy of a sparrowhawk with its head devoid of eyes and beak (empty dummy) served as a baseline alongside dummies of an unmodified sparrowhawk and a pigeon (as a harmless control). The experiment was carried out in two variants, with the complete dummy of the sparrowhawk visible and with the body of the dummy hidden in the bushes, from which only the head was visible. The tits showed no more fear towards the eyeless and beakless dummy than they did towards the pigeon. Towards the dummy with the modified configuration, the tits showed no less fear than towards the unmodified sparrowhawk, but in the case of the variant with an eye above and below the beak, their behaviour was different and can be interpreted as increased fear but also as surprise. Thus, the tits perceive a disturbance in the configuration of the predator faces, but do not show unambiguous signs of holistic processing i.e., impaired recognition of the inverted face.