Raven politics: Understanding and use of social relations

Social life has been suggested as one of the main driving forces for the development of higher cognitive abilities in non-human, and human, primates. Yet there are open questions concerning the mechanisms underlying `intelligent` behaviour and the socio-ecological conditions that promote investment in cognitive skills. Recently, the idea of the bird family Corvidae (ravens, crows, magpies and jays) representing a mirror group to the primates in respect to cognitive capacities has gained momentum. Understanding the social life of corvids may thus be critical in our attempt to understand primate cognition, since comparison between these groups may offer the unique opportunity to identify which cognitive abilities are common to social living irrespective of phylogeny and how selection has acted to produce these solutions. The intend in this proposal is therefore to investigate social complexity as driving force for brain evolution in corvids and to provide a comprehensive study on the use of social knowledge in an avian model system, the common raven Corvus corax. Ravens show striking abilities in judging and manipulating competitors but also engage in referential communication, social learning, and various forms of cooperation on the basis of social relationships. This makes them promising candidates to examine their `political` skills from a Machiavellian and a Vygotskian point of view. Hence, this proposal aims at testing what ravens know about other individuals and their social relations and how they make use of their knowledge in daily life. Studies shall follow two parallel lines of research, building blocks (i) on individual recognition (how many individuals can be remembered and for how long?) and understanding of dyadic and triadic relations (who are my and others` friends?) and (ii) on the formation, regulation, and use of valuable relations under fission-fusion dynamics (when and with whom I have to make friends and how to maintain friendships?). Furthermore, studies shall feature a combination of laboratory and field work by utilizing our unique captive colony of hand-raised adult birds, their yearly offspring that will be observed first in captivity and then in the field, and habituated wild birds. Finally, studies shall be conducted in collaboration with leading experts in primatology, experimental psychology and behavioural biology, enabling me to utilize a variety of methods (e.g. operant procedures, playbacks, matched-controlled observations, hormonal correlates) on one model system and to selectively conduct comparative studies with closely related species to address effects of phylogeny and ecology. The integrative aspect of the proposed project shall open new possibilities in the research on avian cognition and is expected to have both an impact on current hypotheses on mental evolution and a strong outreach component to lay persons. If birds with a radically different neurobiology and evolutionary trajectory to that of primates come to understand, and use, their social world in a similar way to primates, this would provide strong support for the idea of a convergent evolution and help us understand the selection pressures that may have boosted the evolution of sophisticated mental skills in non-human, and human, primates.

Corvids are known for enlarged forebrains and cognitive abilities that rival those of primates. However, compared to primates, little is known about the factors that drive corvid brain evolution. One of the possibilities is life in complex social groups. Species like ravens Corvus corax have been reported to deceive others but also to cooperate with others for access to food. Raven Politics aimed at empirically testing the hypotheses concerning social complexity and intelligence in corvids. We first focused on what ravens understand about other individuals and their social relations. Applying methods from psychology and biology, we showed that ravens i) recognize individual variation in communication (i.e., who is who), ii) remember their relationship to former group members over years (whether they were friends or foes) and iii) respond to simulated rank changes as if they are aware of third-party relationships (who are the others friends and foes). We then focused on how ravens make use of their social knowledge in daily life, combining field and lab techniques. We found that i) ravens show a variety of third-party interactions, including social support in fights and post-conflict consolation, ii) bonded ravens rise in rank most likely because of mutual social support and iii) bonded ravens selectively intervene in others bonding attempts, probably to prevent those from becoming powerful themselves. Ravens are thus capable of showing a sophisticated level of social manipulation that resembles a form of politics hitherto described only from chimpanzees. We finally addressed the question of how raven bonds could work in a system of high social fluidity. Using GPS technology, we revealed different levels of fission-fusion dynamics in non-breeders, with some ravens meeting each other on a daily basis, whereas others meet only once a month or even year. Such a layered social system with different forms of interdependencies resembles that of some mammals, including us humans. These findings have been largely confirmed by comparative studies on crows, indicating that pair-bond-like relationships and temporarily stable subgroups of non-breeders may be typical for corvids in general. Comparative work also involved species like parrots and primates and concerned cognitive aspects of the programme, like paying attention to and learning from others. Taken together, Raven Politics represents the first comprehensive study on the use of social knowledge in an avian model system. It confirms that ravens come to understand, and use, their social world in a similar way to some primates, despite of their radically different brain structures and evolutionary trajectories. The findings thus provide strong support for the idea of a convergent cognitive evolution between corvids and primates. The studies inspired several national and international collaborations, led to a number of follow-up projects, and strengthened the reputation of Austria as one of the main centres for animal cognition.