Cognitive requirements for tool use by New Caledonian crows (Corvus moneduloides)

Abstract

Cumulative technological evolution has been suggested to explain the existence of different pandanus tool designs manufactured by New Caledonian crows. Circumstantial evidence from the distribution of the three tool designs that they manufacture suggests transmission of the designs probably involves accurate social learning, a characteristic considered essential for the cumulative evolution of tools. Recently, Kenward et al. (2005) reported that four hand‐raised crows developed basic stick tool use without social learning. This finding cast doubt on the importance of social learning in the evolution of crows’ pandanus tools in the wild. Here, we report that a naïve male crow at Parc Zoo‐Forestier, Nouméa, developed proficient stick tool use without social input in 2002. In 2004, four captive crows, including the naïve male, that were inexperienced with pandanus material were given an opportunity to use and/or manufacture pandanus tools. Only two of the four birds used the tools but none manufactured tools. Our preliminary findings and the work with the four hand‐raised crows keep open the possibility that the evolution of crows’ pandanus tool designs is based on social learning. We propose that social learning and a disposition to develop basic tool use without social input are both essential cognitive requirements for cumulative technological evolution.