Abstract
Intraspecific social interactions in domestic cats are often categorised as affiliative or agonistic. However, public or professional assessment of encounters can have difficulty distinguishing rough-and-tumble play from true agonism. One possible issue is the potential occurrence of elements of both, play and agonism, within inter-cat play, for example when one cat wants to terminate a bout of play but the other seeks to continue the interaction, which subsequently may provoke more overt agonistic behaviour. To test this hypothesis, we conducted behavioural observations of 105 unique dyadic interactions of domestic cats (N = 210) captured on videos collected from owners and YouTube. We assessed cats for the frequency and duration of six behavioural elements. The dataset was reduced using PCA with a varimax rotation and factor scores were used to classify the population using hierarchical cluster analysis. To validate the identified clusters, the average scores of the constituent factors were compared and the data on interactions were labelled by four cat behaviour experts as "playful", "intermediate" or "agonistic". In addition, to evaluate properties of expert-labelled categories we used linear discriminant analysis followed by an ordinal regression. The results showed considerable convergent validity in factor distributions between clusters and expert-labelled groups: reciprocal wrestling was most closely associated with a group of playfully interacting cats, while vocalisation and chasing were associated with the agonistic group. The intermediate group, while having characteristics of both, was more closely related to the playful group than the agonistic group, with prolonged exchanges of interactive behaviours being a predominant feature. Thus, our findings support the suggestion of there being an intermediate category between mutual social play and agonism. This might escalate into a fully agonistic encounter, but does not necessarily reflect a break down in their social relationship but rather a short-term disagreement in social priorities.