More Clever Corvid Stuff

Nice BBC piece which reports on work that builds on earlier amazing findings relating to corvid tool use. In the first piece of research, Nathan Emery and Christopher Bird have found that Aesop's fable about a crow enjoying a "Eureka" moment by displacing water by throwing pebbles into a jar until the water surface rose to the point that it could drink, may well be grounded in fact. Their rooks have shown that they can plop pebbles into a cylinder containing a floating worm - up to the point where they can reach the worm with their beaks. Two rooks did it spontaneously when first presented with the task, the other two on their second attempt. They used larger pebbles when given variety thereby raising the water level more efficiently and they avoided worms on sand in favour of worms floating on water.

In a separate paper, Alex Kacelnik's group in Oxford report repeating the famous experiment conducted with Betty, just before she died, where the New Caledonian crow used a short tool to retrieve a medium-length tool to retrieve a long tool to pull out food from deep inside a horizontal tube. Four out of seven birds were spontaneously able to use the tools in the correct order, repeating Betty's swansong. As I explain in the book, this is an exceptionally important finding because, had the crows been learning by simple trial and error they would have found it impossible because the reward only comes after successfully negotiating three stages of tool selection. As Kacelnik is reported saying, "We are aware that the animals probably do it by putting together, in creative ways, things that they have learned individually". This is meta-tool use - using a tool to make a tool to use a tool.....and so on, to gain a reward. This is very sophisticated, human-like, cognition.