Laterality in Neotropical Psittacids (Aves, Psittacidae): Evaluation of Its Relationships with Temperament and Social Interactions

Laterality is defined as asymmetries in function or structure in seemingly bilateral structures. In parrots, it can be expressed for various behaviors, for example, the preference for using the monocular visual field of a specific eye or a specific foot for feeding, also known as footedness. The aim of this study was to check for laterality in three Psittacine species and examine its relationship with aspects of their temperament and sociability. We analyzed birds of the following species: Psittacara leucophtalmus (n=15) , Primolius maraca (n=12) , Pionius maximiliani (n=23) . To evaluate laterality, we used the following indicators: footedness, unipedal support while resting, and eye preferences through the monocular visual field during the tests of pebble and seed, novel object, and reaction to person. The pebble and seed test evaluate cognitive capacities and foraging skills of birds by encouraging them to discriminate seeds and pebbles of similar size and color. The temperament was evaluated according to the birds’ individual responses to novel objects and reaction to person tests. Laterality indexes (LI) were calculated based on the frequency of use of each foot and eye, using the equation LI= (L-R)/(L+R), where L represent the left side use and R represents the right. Spearman correlation coefficients were calculated to assess the relationships between laterality and the behavioral aspects investigated (temperament and social behavior). The results indicated the presence of laterality in the three bird species, highlighting the right eye preference and no predominant direction was found for footedness and unipedal support. Significant correlations between eye preference and the four temperament dimensions (activity, boldness, anxiety and proximity to humans) were found. Higher activity was related to greater ocular LI and LI in the pebble and seed test towards the right. Bolder and more anxious birds had lower LI in the human reaction test, thus right eye preferences. Avoidance to humans was related to lower LI in the novel object test, therefore, right eye preferences. No significant correlations were found between laterality and positive or negative social interactions. Our study contributes to the scientific literature by identifying laterality in neotropical species, a topic for which data remain limited. Additionally, it is the first study to demonstrate a relationship between temperament and laterality in psittacids, which could be explained by underlying connections between emotionality and cognition, as observed in other animal species. These hypotheses warrant further investigation in future research. • Laterality and its connections with temperament were investigated in Neotropical • Psittacids. • Laterality was assessed by analyzing foot and eye preferences and unipedal support. • Temperament dimensions were activity, boldness, anxiety, neophilia, and human proximity. • Right eye preference was related to boldness, anxiety, and avoidance to humans. • Laterality can guide more individualized welfare strategies for captive animals.