Cooperative problem solving in rooks (Corvus frugilegus)IntroductionExperiment 1: can rooks cooperate to solve a problem?MethodsStudy animalsApparatusProcedureScoring and data analysisResults and discussionExperiment 2: cognition underpinning cooperationMethodsProcedure and apparatusResults and discussionDelay testChoice testGeneral discussionTests were conducted in accordance with Home Office and University of Cambridge guidelines for animal use.Referencesdoi: 10.1098/rspb.2008.0111, 1421-1429275 2008 Proc. R. Soc. B Amanda M Seed, Nicola S Clayton and Nathan J Emery )Corvus frugilegusCooperative problem solving in rooks ( Referenceshttp://rspb.royalsocietypublishing.org/content/275/1641/1421.full.html#related-urls Article cited in: http://rspb.royalsocietypublishing.org/content/275/1641/1421.full.html#ref-list-1 This article cites 33 articles, 3 of which can be accessed freeSubject collections (1129 articles)behaviour  Articles on similar topics can be found in the following collectionsEmail alerting service hereright-hand corner of the article or click Receive free email alerts when new articles cite this article - sign up in the box at the top http://rspb.royalsocietypublishing.org/subscriptions go to: Proc. R. Soc. BTo subscribe to This journal is © 2008 The Royal Society on March 18, 2010rspb.royalsocietypublishing.orgDownloaded fromCooperative problem solving in rooks(Corvus frugilegus )Amanda M. Seed1,2,*, Nicola S. Clayton1and Nathan J. Emery3,41Department of Experimental Psycholog y, University of Cambridge, Cambridge CB2 3EB, UK2Department of Developmental and Comparative Psychology, Max-Planck Institut fu¨r evolutiona¨re Anthropologie,Deutscher Platz 6, D-04103 Leipzig, Germany3Sub-Department of Animal Behaviour, University of Cambridge, Madingley, Cambridge CB3 8AA, UK4School of Biological and Chemical Sciences, Queen Mary, University of London, London E1 4NS, UKRecent work has shown that captive rooks, like chimpanzees and other primates, develop cooperativealliances with their conspecifics. Furthermore, the pressures hypothesized to have favoured socialintelligence in primates also apply to corvids. We tested cooperative problem-solving in rooks to comparetheir performance and cognition with primates. Without training, eight rooks quickly solved a problem inwhich two individuals had to pull both ends of a string simultaneously in order to pull in a food platform.Similar to chimpanzees and capuchin monkeys, performance was better when within-dyad tolerance levelswere higher. In contrast to chimpanzees, rooks did not delay acting on the apparatus while their partnergained access to the test room. Furthermore, given a choice between an apparatus that could be operatedindividually over one that required the action of two individuals, four out of six individuals showed nopreference. These results may indicate that cooperation in chimpanzees is underpinned by more complexcognitive processes than that in rooks. Such a difference may arise from the fact that while bothchimpanzees and rooks form cooperative alliances, chimpanzees, but not rooks, live in a variable socialnetwork made up of competitive and cooperative relationships.Keywords: corvids; rooks; chimpanzees; cooperation; cognition; tolerance1. INTRODUCTIONAnimal cooperation is a topic that has fascinated researchersfrom many disciplines (Noe 2006), perhaps in part becausecooperation is a defining feature of the social behaviour ofour own species (Moll & Tomasello 2007). For comparativepsychologists, the most pressing question is whether or notcooperation in animals is underpinned by the complexcognitive abilities that characterize cooperation in humans,such as an understanding of the role and intentions of thecollaborative partner.Research addressing this question has focused onprimates, such as chimpanzees, whose cooperative huntingbehaviour in the wild has led field researchers to refer tocognitive sophistication. Boesch & Boesch (1989) describethe hunting behaviour of chimpanzees in the Tai NationalForest as being truly collaborative, with different individ-uals playing different roles. However, research in thelaboratory, motivated by a desire to test this proposalunder controlled conditions, has revealed a limitedtendency among chimpanzees and other primates when itcomes to solving a task requiring the actions of twoindividuals. In several studies, chimpanzees needed trainingor extensive experience before they could successfullycooperate (Crawford 1937; Chalmeau 1994; Hirata 2003).Similarly, while studies of monkey species have foundthat they can learn to solve a problem involvingsimultaneous effort by two individuals, their seeminglycooperative behaviour may come from a mutual attractionto the apparatus and the food, resulting in fortuitousco-production rather than behavioural coordination or anunderstanding of the role of the partner (Petit et al. 1992;Chalmeau et al.1997; Visalberghi et al. 2000). The subjectsin these studies were no more likely to pull when theirpartner was near to the other handle. However, Mendres &de Waal (2000) argue that capuchin monkeys (i) under-stand when cooperation is necessary, because the capuchinsin their study glanced at their partners more often when theefforts of two monkeys were required for success and(ii) display behavioural coordination, because the monkeyspulled more often when their partners were in the vicinity ofthe apparatus, and putting an opaque barrier between thesubjects resulted in significantly poorer performance.Similarly, Cronin et al.(2005)report that cotton-toptamarins, Saguinus oedipus, solve a problem requiring twoindividuals to pull simultaneously, and that they pullsignificantly more often when their partner is present thanwhen they are alone. However, it should be noted that inboth studies the monkeys still pulled the handle (albeit lessfrequently) when the partner was out of the testing room, afinding that questions the notion that they had a robustunderstanding that a partner was required.Recent work by Melis et al. (2006a) investigatedwhether social constraints might explain the limitedsuccess of chimpanzees in the previous studies ofcooperation. Pairs of chimpanzees were tested for theirtendency to share food before being tested on a taskrequiring the simultaneous pulling of two ropes to bring ina platform containing food. The tolerant pairs that wouldProc. R. Soc . B (2008) 275, 1421–1429doi:10.1098/rspb.2008.0111Published online 25