Facial color patterns and intraspecific facial signaling complexity in domesticated cats (Felis silvestris catus)

Recent studies have revealed an inverse relationship between the complexity of facial color patterns and the intricacy of facial signaling. As facial color patterns become more elaborate, facial signaling complexity decreases, because intricate colors may distract from and hinder the perception of subtle facial muscle movements. Recent studies have confirmed this trade-off across multiple primate species and have also identified it within domesticated dogs. The goal of our current study was to assess whether such a trade-off exists among other domesticated species, such as cats ( Felis silvestris catus ). Data were collected at a cat café, including 53 adult domestic shorthairs that vary extensively in their fur colors and patterns. We constructed a facial color pattern complexity scoring rubric that is consistent with previously published work. This rubric was implemented using automated approaches (Google Gemini) to ensure consistency in the evaluation of cat faces. We utilized systematic and standardized methods to study cat facial muscle movements (catFACS). We assessed and operationalized the complexity of facial signaling based on three criteria: (1) the number of distinct types of facial muscle movements produced by each cat (AU Type); (2) the number of unique combinations of facial muscle movements produced by each cat (AU Combo); and (3) the total number of discrete facial muscle movements that typically make up each cat's facial signals (AU Length). Ordinal regressions were used to evaluate the relationship between our independent (facial color pattern complexity scores) and dependent (AU Type, AU Combo, AU Length) variables. Our results indicate that there are no statistically significant differences in our three measures of facial signaling complexity based on cat facial color pattern complexity scores. Further research with other felids, both domestic and wild, is necessary to explore these relationships more thoroughly.