Initial Evidence for Eliciting Contrafreeloading in Grey Parrots (Psittacus erithacus) via the Opportunity for Playful Foraging

Contrafreeloading is the choice to perform a physical task to access food over freely available food, a behavior pattern contrary to the predictions of both optimal foraging and learning theories. This study examined the presence and degree of contrafreeloading in Grey parrots (Psittacus erithacus) and the possible interpretation of such behavior in the context of play. Experiment 1 presented 4 subjects, Griffin, Athena, Franco and Pepper, with container pairs holding more- or less-preferred free or enclosed food items. Degrees of contrafreeloading were classified as follows: calculated contrafreeloading (working to access preferred food over less-preferred, freely available food); classic contrafreeloading (working to access food equal in value to freely available food); and super contrafreeloading (working to access a less-preferred food over preferred, freely available food). Of these three, Griffin significantly preferred classic and calculated contrafreeloading; Athena, Pepper, and Franco significantly preferred calculated contrafreeloading. Experiment 2 examined a more ecologically relevant contrafreeloading task in 5 parrots, Griffin, Athena, Lucci, Pepper, and Franco, using shelled and unshelled nuts. Athena and Franco significantly preferred cracking the shell to obtain the nut (contrafreeloading); Griffin and Lucci did not; Pepper chose at chance. We examine numerous possible explanations for their behavior and suggest that individual differences in contrafreeloading among the Grey parrots could relate to which task each considers some form of play.