Abstract
Prosocial behaviours - behaviours that benefit others at low or no cost to the actor - have been associated with cooperative breeding, nesting ecology, and overall levels of dependency and social tolerance. To confirm whether these factors drive the evolution of prosociality, we need to generate more robust data using a comparative approach with a standardised procedure. Parrots present a compelling model group to test this further due to their large brains, and advanced cognitive abilities. Using the group service paradigm, in which individuals can provide food to group memebers, we tested four distantly related parrot species with different socio-ecological backgrounds. All species provided food to group members at moderate to high levels and some individuals of all species were able to discriminate between situations in which food could be provided to others or not. All parrots demonstrated dyadic preferences by providing more food to both affiliated and non-related partners, with sex-specific effects varying between species. Furthermore, males from species that engage in cooperative breeding and territorial nesting provided the most food to members of their group. This implies that cooperative breeding and a reliance on other group members may be driving factors in the evolution of prosocial behaviour in parrots.