| Summary: | Play behaviour and agonistic behaviour are two essential elements in the daily life of social animals. Within social play, play-fighting is the most common and riskiest because it involves easily misunderstandable patterns recruited from agonistic behaviour. For this reason, communication is crucial in making the playful session rewarding for all the participants and several signals have undergone the process of ritualization to help informing the playful mood. One example is the relaxed open mouth display (ROM), which is, according to several authors, the ritualized version of the biting action. During agonistic encounters, escalation is preferentially avoidable due to the high risk of injuries. Animals can present several aggressive signals efficient in deterring the opponent, making communication central also in this scenario. The aim of this thesis is to compare visual signals, in particular the facial expressions used in the playful and the aggressive domains, in our model species, the social carnivore wolf (Canis lupus). Wolves are a valuable candidate for our investigation because besides being social they are very competitive, start engaging in play-fighting from a very early stage of life and keep playing as adults. On the other hand, wolves live in a hierarchical society and conflicts among individuals can occur often. Additionally, wolves present a wide range of facial expressions and heavily rely on visual communication during playful and aggressive encounters. In particular a motivational model of different facial expressions based on increasing fear and aggressiveness was proposed by Zimen (1971) that described the gradient of variability of wolves’ threatening displays. However, a quantitative description of these facial signals was still missing. Video and acoustic data were collected from the 2nd of October to the 5th of Nov 2021 in the ‘Belpark’ faunistic park in Spormaggiore (Trento, TN, Italy) on a colony of 10 captive grey wolves (Canis lupus lupus, 5 males and 5 females, all adults). Videos ...
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