Tool-related problem solving in corvids and parrots

The study of physical cognition in birds has shown great progress in recent years, and revealed that avian experimental models are highly informative with respect to the evolution of tool use and other forms of physical problem-solving competence. The focus of this project will be on members of the two avian families that parallel the cognitive sophistication of the great apes in many respects, namely corvids and parrots. The first part of the study concentrates on physical skills within a novel framework of unrewarded object play, targeting profiles of object-object relationships established by three corvid species (jackdaws, ravens and New Caledonian crows) and five parrot species (Goffin cockatoos, Vasa Parrots, kea, Hahn`s macaws and caiques). On this base, we thereafter concentrate on the acquisition of tool use, which is arguably one of the most noteworthy functional object relationship established by non-human animals. We will test systematically for various modes of tool use in the only known habitually tool using corvid species, the New Caledonian crow, and in a non-tool using corvid, the jackdaw. We will also study parrot for which our pilot observations demonstrate the presence of conspicuously elaborate object-related play behaviour and the capacity for tool use, the Goffin cockatoo. We will thereupon investigate the same animals` perception of the relationship between the physical properties of their tools and the corresponding substrate upon which the tool is used. For this we will include kea among the study species, which have already proved skilful in tool-related studies in the past.

The study of physical cognition in birds has shown much progress in recent years, and revealed that avian experimental models are highly informative with respect to the evolution of tool use and other forms of physical problem-solving. The focus of this project was on members of the two avian families that parallel the cognitive sophistication of the great apes in many respects, namely corvids and parrots. The first part of the study concentrated on physical skills within a novel framework of unrewarded object play, targeting profiles of object-object relationships established by three corvid species and nine parrot species. Paralleling previous results in primates we found that only species which are associated to high level technical problem solving abilities and tool use incorporate complex object-object and object-substrate combinations in their unrewarded object manipulation (play). We thereafter focussed on the acquisition of tool use, which is arguably one of the most noteworthy functional object relationship established by non-human animals. We found that even closely related species that can acquire the same type of tool use (dropping a stone into a tube to free a food reward) use highly different cognitive processes to achieve the same goal depending on their respective ecologies. To summarize our most important further results: We found that a cockatoo that has no genetic predisposition to use tools can transmit tool use and manufacture to other conspecifics by social learning. They can further decide between a tool and an immediate food reward based upon the difference in quality between the immediate and the out-of reach food type as well as the functionality of the available tool with the apparatus the out-of reach food is trapped inside.