Laterality in Psittaciformes: evaluation of behavioral and temperament aspects

Abstract

Laterality is characterized by the asymmetrical use of cerebral hemispheres or bilateral structures. In psittacids, it can be expressed through the preference for using monocular vision or a specific foot for feeding. The objective of this dissertation was to evaluate laterality in Psittaciformes and relate it to temperament, emotionality, and social aspects by reviewing the scientific literature and applying established methodologies to identify this feature in Neotropical Psittaciformes. The specific objectives of this dissertation were: to gather information on laterality in Psittaciformes through a scoping review (SR) and bibliometric analyses (Chapter 1); to identify laterality in three species of psittacids (Psittacara leucophthalmus, Primolius maracana, Pionus maximiliani) and to relate the phenomenon to aspects of temperament and sociability (Chapter 2). In Chapter 1, 20 publications were included in the SR, with 40% conducted in Australia, 35% in the United States, and 5% in Brazil. Laterality was studied in 31 genera of Psittaciformes, of which 77.4% occur in Oceania, 16.1% in America, and 6.4% in Africa. The preference for using a specific foot for feeding was evaluated in 80% of the studies, reporting an average left-foot preference of 61.1% (ranging from 5.0% to 100%). Eye preference was evaluated in 20% of the studies. The most investigated topic was the relationship between laterality and cognition (20.0%). In Chapter 2, the results indicated the presence of laterality in the three analyzed species, highlighting a preference for the right eye. The strength of laterality was analyzed by laterality index which ranges from -1 (totally right-eyed) to 1 (totally left-eyed). For footedness and unipedal support, there was no predominant direction. Significant correlations between visual preferences and temperament dimensions were observed (activity, boldness, anxiety, and closeness to humans). The higher the activity, the lower the total LI and LI in the pebble and seed test, indicating a greater preference for the right eye. The bolder and more anxious birds had a lower LI in the reaction to person test, also resulting in a preference for the right eye. Greater avoidance of humans correlated with increased right eye use (lower LI in the novel object test). No significant correlations were found between laterality and positive or negative social interactions. The results of this dissertation add data to the scientific literature on laterality in Psittaciformes and provide an overview of the topic. Additionally, our findings reinforce the benefits of understanding the relationship between laterality and individual differences for animal welfare, offering a non-invasive method to identify birds more prone to stress, fear, and aggression. This enables the elaboration of personalized management strategies for captive animals, considering individual emotional responses. This was the first study to identify and relate laterality with temperament dimensions in Psittaciformes.