The performance of rooks in a cooperative task depends on their temperament
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In recent years, an increasing number of studies demonstrated the existence of consistent individual differences in behaviour, often referred to as differences in temperament or personality, in a wide range of animal species. There notably is a growing body of evidence showing that individuals differ in their propensity for risk taking or reacting to stressful situations. This variation has been related to differences in learning abilities or performance in cognitive tasks. In the present study, we examined the consequences of inter-individual variation in boldness on performance in a cooperative task in rooks (Corvus frugilegus). Birds were tested individually to measure a number of behavioural parameters related to boldness. The level of a stress-related hormone, corticosterone, in the faeces of each bird was measured under control conditions and after a stress-provoking event. In parallel, we conducted a cooperative string pulling task in which birds were tested in dyads. Successful cooperation depended to a large extent on the temperament of the two partners involved. Temperament, in turn, correlated well with corticosterone levels under stress. Bolder individuals appeared to be more willing to participate in the task, whereas shyer individuals were more influenced by the behaviour of their partner. These findings suggest that a rook’s temperament can limit its options of forming successfully cooperating partnerships under stressful conditions.
KeywordsCooperation Boldness Temperament Personality Corvus frugilegus Rook Stress Corticosterone
This work received funding under the GEBACO contract n. 28696 (EC-Framework 6 programme 2002–2006). C. Scheid was supported by a studentship of the French Ministry of Research. We are grateful to G. Gaudiot for the conception of the experimental apparatus, to H. Gachot and S. Zahn for the DNA sexing, to E. Möstl and his team at the University of Veterinary Medicine, Vienna for the hormone analyses, to N. Poulin for advises concerning statistics and to J. Schmidt, T. Hindelang, L. Durand, J. P. Robin and S. Calibre for their help.
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