Four Grey parrots (
Psittacus erithacus) were tested on their ability to obtain an item suspended from a string such that mutiple, repeated, coordinated beak–foot actions were required for success (e.g., Heinrich
1995). Those birds with little training in referential English requests (e.g.
I want X
) succeeded, whereas birds who could request the suspended item failed to obtain the object but engaged in repeated requesting.
Keywords Grey parrots - String-pulling - Referential requesting