Exploration, nephobia and social cognition in ravens and jackdaws: a comparative and experimental study of interspecific and intraspecific differentation

With this project we intend to test the general hypothesis that cognitive domains were selected to fit the biology and lifestyle of species, including social organization. Based on our previous projects on the cognitive biology in ravens and greylag geese, we chose to compare exploration, neophobia and their relationships with social dispositions and social cognition in two closely related, yet ecologically and socially distinct species of corvids, the common raven (Corvus corax) and the jackdaw (Corvus monedula). Exploration and neophobia (E&N) are cognitive domains, which crucially affect information acquisition and therefore, are essential to understand the cognitive ethology of species and individuals. Via 5 experimental series with 12 standard-hand-raised (to control for ontogeny) individuals per species we intend to investigate 1) species differences in E&N, 2) whether and to what degree individual E&N within the species reaction norm can be modulated via early (post-fledge) experience, 3) how the expression of E&N is related to excreted corticosterone (analysed by EIA) and how behavioural and hormonal responses can be modulated by the presence of a social companion. Because of their co- feeding with predators, we expect ravens to be more neophobic than jackdaws. In addition, ravens rely more carcasses as opposed to widely distributed food, such as insects in jackdaws. We therefore predict that ravens will have developed more differentiated means of obtaining food from conspecifics than jackdaws. Hence, we plan to investigate 4) how E&N is related with scrounging over food. Because of their feeding ecology, ravens rather than jackdaws cache food as an individual tactic to obtain food. Hence, we finally plan to examine 5) how ravens and jackdaws differ in their abilities of tactical deception over food caching. We generally predict that because of their biology, ravens will be more explorative, but also more neophobic than jackdaws. We expect that the behavioural expression of E&N will depend on social organization. The less permanent and more flexible social structures of ravens as compared to jackdaws will, for example, produce more diverse scrounging patterns in ravens and further their ability to manipulate information-transfer to conspecifics over cache location and raiding intentions of conspecifics. The Konrad Lorenz Research Station has a tradition in cognition and personality research in ravens, geese (Anser anser) and other bird species. This combination of know how and crucial resources (aviaries, equipment, etc.) makes the KLF an ideal place to conduct the proposed research.

How animals see the world is of long-standing interest for behavioural biologists and for humans in general. Our results on exploration and neophobia add to the rapidly accumulating evidence of a striking cognitive convergence between corvids and primates. Vertebrate cognitive potentials may be considered as variations of basic themes, which vary between species, depending on ecology and social context. We therefore, compared two closely related, but ecologically and socially distinct corvid species, Common ravens and jackdaws. Series of experiments, included, but were not restricted to, exploration and neophobia. In essence, we found, that ravens are more individualistic explorers, but are also more neophobic than the socially more coherent jackdaws. Ravens are varied foragers which have a sustained interest in potential sources of food, including the caches made by conspecifics. In contrast, jackdaws forage on items such as insects and plant matters which require less sophisticated extraction techniques. Also, jackdaws do not cache. This may explain why jackdaws are generally less interested in novel objects and show considerably shorter attention spans than ravens. In addition to these differences between species, we also found inter-individual variation. For example, we showed individual consistency in boldness to explore novel objects in both, ravens and jackdaws. This was linked with stress hormone responses, analysed non- invasively from faeces. Hence, exploration and neophobia are modulated by individual coping style (personality) in the two species. Depending on these individual characteristics and on social relations, the presence of a conspecific either facilitated or delayed approaching novel objects in ravens . Jackdaws were generally more socially dependent in their approaches to tasks than ravens. The central themes of this research project were taken care of by two PhD students, Mareike Stoewe and Christine Schwab. To gain a more general view of raven and jackdaw cognition as a necessary background for the interpretation of our central results, a number of social and cognitive features were investigated and experimental paradigms developed. This included general learning abilities and concept formation (F. Range, D. Ujfalussi), the social network (M. Loretto), lateralization and eye use (A. Fanzutti), gaze following and spatial memory (A. Braun, C. Schlögl), string pulling (T. Bugnyar, B. Bonechi, D. Gaede, R. Swoboda) and modifyers of competition (M. Gattermayr). Towards the end of this project we also started to adopt a quail model for the investigation of maternal effects on offspring coping style, which seems a crucial factor in inter-individual modulation of exploration and neophobia (P. Johnston). All experimental work was done with hand-raised birds, 13 ravens (2004 in Gruenau and another group in Vermont/US) and 30 jackdaws. P16939-B03 resulted in 17 scientific manuscrips (including in prep) and 33 contributions at international meetings and in an extensive cooperation network with 8 research groups in Europe and the USA. Finally, our work attracted continuous media attention, resulting in a number of contributions in print media, radio and TV inside Austria and abroad.