Research at the KLF

Fairness and inequity avoidance in carrion crows (Corvus corone corone)

funded by: „For Women in Science“ L’Oreal Austria, ÖAW and BMWF

project leader: Dr. Claudia Wascher

Different forms of cooperative behaviours can be observed in human as well as non-human animal societies (e.g. cooperative breeding, cooperative hunting, alliance formation). What makes these cooperative behaviours so attractive for scientific research is the element of instability. Why should individuals invest without a guarantee of net returns? In the proposed study I plan to investigate a specific aspect of cooperation namely the sensitivity towards unequal reward or effort distribution. For a long time, inequity avoidance has been thought to be a uniquely human feature, until it has been shown in primate species and recently, also in dogs. Until the present day all studies focused on mammalian species. I plan to investigate sensitivity to unequal reward structure for the first time in a bird species, the carrion crow (Corvus corone corone). Tests will be conducted on a group of 8 captive carrion crows at the Konrad-Lorenz Forschungstelle (KLF) in Upper Austria. In the last two years these birds were trained to exchange a token (non-edible item) for food with a human experimenter. This procedure has been applied in primate species to answer questions like, how individuals deal with delay of reward (Dufour et al. 2007), differences in food quality (Drapier et al. 2005) or unequal reward (Brosnan & De Waal 2003; Brosnan et al. 2005). To my knowledge, the crows at the KLF are the first bird species capable to perform in exchange tasks. I plan to replicate tests conducted in primates on inequity avoidance starting in November 2009. For comparative reasons, I will follow the methods used by Brosnan and co-workers (2003; 2005): A focal subject and a model individual will be tested together in 4 experimental conditions: (1.) equity test: both subjects will receive a low-value food reward for exchanging; (2.) inequity test: the test subject witnesses the model individual exchanging for a high value reward, afterwards the focal subject itself, receives a low-value reward for the exchange; (3.) effort control: the focal subject watches the model individual receiving high quality reward without exchanging, then the focal subject has to exchange for the reward; (4.) food control test: the high-value reward is presented but not given to the model, afterwards the focal subject has to exchange for the reward. For each individual and in each condition I will measure the frequency of refusals to exchange and the latency to exchange. In a final step, starting in April 2010, I will investigate how social relationships affect inequity aversion. It has been previously shown in chimpanzees that tolerance for inequity increases with social closeness (Brosnan et al. 2005). I will test all individuals in the inequity test once with an affiliated and once with a non-affiliated social partner. To be sensitive for other individuals efforts and payoffs compared to the own ones is thought to be a crucial cognitive skill for cooperation but until now has only be shown in mammalian species. I expect carrion crows, to be sensitive to inequity and to respond with refusal to exchange when being unequally gratificated. If they are also sensitive to the effort an individual is investing, they should also respond with refusal in the effort control condition, when another individual receives gratification without the effort of exchanging whereas the focal individual has to exchange to receive the reward. Additionally, I also expect the identity of the model individual to influence the tolerance to inequity. When tested with affiliated individuals focal subjects should refuse less frequent compared to being tested with non-affiliated individuals. The objective of the proposed study is to examine a form of fairness (inequity aversion) in a bird species. In a broader sense, however, my goal is to initiate a research program to investigate carrion crows cooperative skills, aiming at a better understanding of the evolution of cooperative behaviour and its cognitive underpinnings.