|Ivo with one of the crows at Auguste von Bayern's lab.|
Busy with another study, lead author Ivo Jacobs noticed a unique behaviour in a group of captive New Caledonian crows; he saw how one individual slipped a wooden stick into a metal nut and flew off, carrying away both the tool and the object. This and five successive occasion of tool transport resulted in the paper: "A novel tool-use mode in animals: New Caledonian crows insert tools to transport objects", published in Animal Cognition last week.
New Caledonian crows (Corvus moneduloides) rely heavily on a range of tools to extract prey. They manufacture novel tools, save tools for later use, and have morphological features that facilitate tool use. We report six observations, in two individuals, of a novel tool-use mode not previously reported in non-human animals. Insert-and-transport tool use involves inserting a stick into an object and then moving away, thereby transporting both object and tool. All transported objects were non-food objects. One subject used a stick to transport an object that was too large to be handled by beak, which suggests the tool facilitated object control. The function in the other cases is unclear but seems to be an expression of play or exploration. Further studies should investigate whether it is adaptive in the wild and to what extent crows can flexibly apply the behaviour in experimental settings when purposive transportation of objects is advantageous.