A novel tool-use mode in animals: New Caledonian crows insert tools to transport objects.

Mathias Osvath,Auguste Von Bayern,Ivo F Jacobs

doi:10.1007/s10071-016-1016-z

Mathias Osvath, Auguste Von Bayern + Show 1 more

Open Access

https://doi.org/10.1007/s10071-016-1016-z

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Abstract

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.Electronic supplementary materialThe online version of this article (doi:10.1007/s10071-016-1016-z) contains supplementary material, which is available to authorized users.

Highlights

New Caledonian crows (Corvus moneduloides) are habitual and proficient tool users. They use and manufacture tools in several modes in both natural settings and captivity
Two New Caledonian crows exhibited a novel tool behaviour not previously reported for any non-human species
No specific permissions were required under German law for this noninvasive study

Summary

Introduction

New Caledonian crows (Corvus moneduloides) are habitual and proficient tool users. They use and manufacture tools in several modes in both natural settings and captivity (animal tool use is reviewed in Bentley-Condit and Smith 2010; McGrew 2013; Shumaker et al 2011, with additional modes in New Caledonian crows described by Jelbert et al 2014; Taylor et al 2012; Troscianko et al 2008; von Bayern et al 2009). A large portion of their daily caloric intake may be obtained through tool use (Rutz et al 2010) Their reliance on tools has possibly resulted in morphological adaptations: a wide binocular overlap, eye laterality, and a short, straight, stout beak (Martinho et al 2014; Matsui et al 2016; Troscianko et al 2012). They secure tools after extracting prey by trapping it underfoot or storing it in a hole—doing so more often when tool availability is limited and the cost of tool loss is higher (Hunt 1996; Klump et al 2015). We discuss the possible functions of this tool-use mode in the context of both the current investigation and the crows’ natural environment

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