Why is tool use so rare, and why are we humans so good at it?

We address this long-standing puzzle by studying animals that have the capacity to use basic foraging instruments. But, rather than investigating our primate cousins, we work on tool-using birds.

Since 2005, our research has focussed on the New Caledonian crow, which is one of the world’s most accomplished tool users. These birds live on a remote tropical island in the South Pacific where they use bill-held tools for extracting prey from deadwood and vegetation. They use at least three distinct tool types and elaborately craft some tools from raw plant materials. They may even have the capacity to refine their tool designs, producing ever-more complex and efficient technologies – a process generally considered a hallmark of human material culture.

While the species has attracted considerable attention with its impressive tool-making skills, it has so far remained a curious oddity. Why do they, but apparently no other members of the crow family use tools?

There are over 40 species of crows worldwide, many of which poorly studied, and a few years ago we started wondering whether there might be undiscovered tool users amongst them. We began to search for species that look similar to the New Caledonian crow, whose unusually straight bill is perfectly-adapted for wielding stick tools. It seemed to us that the Hawaiian crow – one of the world’s rarest birds – was a particularly promising candidate.

Our hunch was right: we have recently discovered that Hawaiian crows are, indeed, exceptionally good at using foraging tools – a breakthrough that was published as the cover story of Nature.

This discovery provides fresh insights into the ecological drivers of animal tool behaviour. Both the New Caledonian crow and the Hawaiian crow evolved on remote tropical islands that lack woodpeckers and major predators – perfect conditions, apparently, for canny crows to develop impressive tool-use skills.

We are currently presenting our crow research at the Royal Society Summer Science Exhibition in London. The exhibition is open – free of charge – until Sunday July 9th.