Psience Quest

Quote:Seventeen of the birds were then observed during two trials each on separate days. In both, they were presented with logs containing different sized holes baited with meat or spiders. In one treatment they had access to branches appropriate for hooked tool construction and the other with only straight sticks.

"Subjects were significantly more likely to express safekeeping behavior (storing tools underfoot or in holes) when foraging with hooked stick tools they had manufactured… than when foraging with non-hooked stick tools they had sourced from leaf litter," the team wrote in their paper.

This remained true when the hooked tools were supplied by researchers, suggesting the tool itself was the subject of assigned value rather than the time they put into it.

What's more, they used the most secure safekeeping method – storing the tools in holes – far more for hooked tools.