Species-wide manufacture of stick-type tools by New Caledonian Crows

Abstract

We describe 15 additional stick-type tools collected from New Caledonian Crows since the first detailed description of these tools in 1996. All 15 tools were plant material and most were manufactured from living plants. Eleven of the tools were twigs or the midribs of leaves, one was a section of bamboo stem, and the remaining three tools were sections of fern stolon. Nine tools were hooked, including examples of two new varieties of these tools made from a thorny vine and fern stolon. The use of a diverse range of raw material to manufacture tools, and material-specific tool-making techniques further demonstrates flexibility and innovation in Crows' tool manufacture. Our findings indicate that stick-type tools are used widely by Crows and that they are used throughout the year. New Caledonian Crows join hominids and Chimpanzees as species with the flexible and widespread manufacture of stick-type tools. They join hominids as species with the widespread manufacture of distinct types of tools.