Abstract

New Caledonian crows (Corvus moneduloides) are renowned for using tools for extractive foraging, but the ecological context of this unusual behavior is largely unknown. We developed miniaturized, animal-borne video cameras to record the undisturbed behavior of wild crows and to produce a detailed account of the species' natural foraging ecology. Our video cameras revealed that prey items collected during long bouts of ground foraging are considerably smaller than the woodboring beetle larvae that crows often hunt with stick tools. This finding highlights the potential economic and evolutionary relevance of tool use for New Caledonian crows. We also recorded a newly observed mode of tool use and a hitherto unknown tool material, illustrating that tool-assisted foraging by crows is more plastic than previously thought. Video tracking may have considerable potential for studying the behavior and ecology of many other bird species that are shy or live in inaccessible habitats.