Two hand-reared parrots took part: Griffin, the dominant bird who is 14 years old, and Arthur, who is 11. The birds live in large individual cages in the same room as each other, and often take part in studies of parrot cognition. This means they were well placed to understand the task involved: choosing one of four coloured cups, each of which has a different meaning.
For the purposes of this study, the cups were as follows:-
Green cup – sharing. The bird and their partner both get a treat.
Pink cup – selfish. The bird gets a treat but the partner does not.
Orange cup – giving. The partner gets a treat, but they do not.
Violet cup – null. No one gets a treat.
The tray was presented to the first bird, who had to make a choice, and treats were distributed accordingly. Then the second bird got to make a choice. In total, there were fifty sessions, in which each bird got to make ten choices. Griffin led in 24 of the sessions, and Arthur led in the other 26 (it was meant to be equal, but there was a mistake).
The birds did not choose randomly, and nor did they co-operate by always choosing the sharing cup, which would have maximized the rewards for both of them. Griffin, the dominant bird, chose selfishly when he went first, but when he had the second choice he continued to sometimes share. Arthur became more selfish over the trials, whether he was leader or follower. And while Arthur was silent throughout, Griffin sometimes said ‘want nut’ or ‘nut’, or squeaked in a frustrated way, in response to his own or Arthur’s choices.
Of course, the parrots already had a relationship with each other which may have affected their choices. Perhaps Arthur became more selfish over time because, as the subordinate bird, it was unusual that he had a chance to do so without reprisal.
The second experiment was similar, except the birds were paired with several humans. One human was always selfish, one was always giving, and the other copied whatever the parrot had just done. In most cases, the birds had ten sessions of ten trials each (i.e. ten choices for the bird and ten for the following human), although there was some variability due to students’ schedules. The main difference was that for Arthur, towards the end, there was a three week hiatus in testing because of students’ exams.
As before, both birds avoided the giving and null cups. Griffin’s behaviour changed over the time of the trials. When the human was giving, Griffin began to share more over time. When the human was selfish, he became more selfish over time. With the copycat, it wasn’t clear that Griffin understood this, although there was a slight increase in sharing behaviour.
Arthur’s results were complicated by the three week gap in testing. He is a bird who doesn’t respond well to absences by people he is used to interacting with, and often greets them on their return by biting or shunning them. Prior to the gap, he was tending towards more sharing with the ‘giving’ human, but after the gap he reversed this behaviour. He also didn’t seem to like the copycat, and often chose the ‘null’ cup, which may have been his way of saying he had had enough.
These results show that Griffin seemed to understand the concept of sharing, since he tended to pick the ‘share’ cup more often with the ‘giving’ human (note that he wasn’t copying the human, because that would have involved picking the ‘giving’ cup). Both birds showed awareness of the value of the choices. Their choices changed over time and (at least to some extent) according to what their partner did.
One of the things I especially like about this study is that the parrots’ personalities shine through.
Do you have a bird at home, and if so what kind?
Péron F, John M, Sapowicz S, Bovet D, & Pepperberg IM (2012). A study of sharing and reciprocity in grey parrots (Psittacus erithacus). Animal cognition PMID: 23065183