The development of pandanus tool manufacture in wild New Caledonian crows

Abstract

New Caledonian crows have remarkably complex tool manufacturing abilities. Here we document the ontogeny of pandanus tool manufacture in wild NC crows. Our results show that the development of wide pandanus tool manufacture is a lengthy process comparable to the development of tool use in primates. Juveniles pass through four main stages of tool manufacture before they acquire adult-like proficiency. By 10 to 12 months of age most juveniles can manufacture tools with adult-like competency, but adult-like speed in manufacture and tool use is only reached in their second year. Whilst individual trial and error learning appears to play a major role in juveniles' development of pandanus tool skills, this development takes place in an environment scaffolded by parental birds. Juveniles stay close to their parents for their first year and have ample opportunity to observe parental tool manufacture and use. Parents influence the juveniles' early learning by leading them to Pandanus sp. trees where they provide discarded tools for early tool use. Exposure to parental tools might help juveniles form a mental template of functional tool design and, thus, facilitate the faithful transmission of local design traditions.