Ravens (Corvus corax) are indifferent to the gains of conspecific recipients or human partners in experimental tasks
Although cooperative behaviours are common in animals, the cognitive processes underpinning such behaviours are very likely to differ between species. In humans, other-regarding preferences have been proposed to sustain long-term cooperation between individuals. The extent to which such psychological capacities exist in other animals is still under investigation. Five hand-reared ravens were first tested in an experiment where they could provide food to a conspecific at no cost to themselves. We offered them two behavioural options that provided identical amounts of food to the actor and where one of the two options additionally delivered a reward to a recipient. Subsequently, we made the ravens play a no-cost cooperation game with an experimenter. The experimenter had the same options as the animals and matched the ravens’ choices, making the prosocial choice the more profitable option. In both conditions, ravens were indifferent to the effects of their choices and hence failed to help conspecifics and to cooperate with the experimenter. While our negative results should be interpreted with care, overall, our findings suggest that the ravens had no understanding of the consequences of their actions for a potential recipient. This study adds to several others that have used a similar set-up and have reported negative results on other-regarding preferences in animals.
KeywordsRavens Corvus corax Other-regarding preferences No-cost cooperation
We thank Kurt Kotrschal, Chris Schloegl and Anna Braun for their great support on site, and three referees for their constructive comments. We thank also Sharon Wismer for having improved our English and Albert Ros for his advices regarding the power analysis. RB is financed by the Swiss Science Foundation. The study has been co-funded by the COCOR project I 105-G11 conducted within the ESF-EUROCORES framework TECT. Permanent support is provided by the ‘Verein d. Förderer KLF’ and the Herzog von Cumberland Stiftung. We are grateful to the zoos Wien and Wuppertal for the donation of raven nestlings and P. Sömmer for help with capturing wild birds. Permission to take nestlings from the wild was derived from the Ministerium für Landwirtschaft, Umweltschutz und Raumordnung des Landes Brandenburg.
Conflict of interest
The authors declare that they have no conflict of interest.
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