A crow species renowned for its use of tools has a time-saving trick — stashing the same tool for future use.
New Caledonian crows (Corvus moneduloides) invest much time and energy turning sticks into hooks to extract food from small cavities. To see what happened to the tools when they were not in use, Barbara Klump and Christian Rutz at the University of St Andrews, UK, and their colleagues offered crows food hidden in holes in a block of wood. They found that, while they ate, the crows usually pinned their tool underfoot (pictured) or stashed it in a hole between uses. Crows foraging up high — where a fallen tool would be harder to retrieve — were more apt to store tools in holes than were birds lower down.
Such safekeeping probably mitigates the cost of tool-making, allowing this complex behaviour to evolve, the authors say.
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Crafty crows keep their tools handy. Nature 521, 397 (2015). https://doi.org/10.1038/521397b