Science Interviews

Clever Corvids

Chris Bird -   We’ve been looking into the tool use of rooks.  Now, rooks are a member of the corvid family, the crow family, and the crow family has been known to be really intelligent, and probably the most intelligent of the birds.  They have a really large brain-to-body size ratio.  They are capable of doing some quite remarkable things with objects, using them as tools to solve particular problems.

Meera -   So knowing about this intelligence to do with rooks, you’ve been doing some interesting experiments with them to find out just how smart they are?

Chris Bird -   Yeah, precisely.  We’ve basically been giving them tool use experiments where they have to solve a problem that they’ve never seen before.  When we‘re giving them these problems, we’re looking at whether they’re able to solve them using an understanding of how the problem works and an understanding of how the tool works.  When we’re looking at their solutions, we’re looking at what they do on the very first trial.  So not whether they’re solving it through trial and error but whether they’re solving it through insight into the problem. Basically, what we've found is that they’re capable of showing these insightful solutions to novel problems using tools.

Meera -   How have you actually gone about experimenting this?

Chris Bird -   We’ve basically given them a variety of tests.  In the first set of tests, we gave them an apparatus which had a platform on which a wax worm, their favourite food was suspended and the birds couldn’t reach that.  But they could collapse a platform by dropping a stone down the tube and they would select the right size and shape of stone depending on the diameter of the tube.  So they were really conscious of the properties of the tool they were using.  They also were able to solve that problem by using sticks.  So they would use a stick to collapse a platform, they’d also modify the stick to make it able to fit into the tube and they were also capable of meta-tool use which is sequential tool use, using one tool to get another tool.  We gave them a second set of experiments where they had a clear Perspex tube about 15 cm tall with a small cardboard bucket in the bottom.  In that bucket was a couple of their favourite worms again and we wanted to see whether they were capable of using a hook-like tool to extract the bucket and get at the worms.  That’s something which New Caledonian crows have been shown to do in the wild.  They’ve been shown to use hook tools and even to manufacture hook tools in order to pull out grubs from holes in the trees.  So we gave the rooks these experiments and found that they were just as capable of using a hook tool to extract the bucket.  Not only that, but when you gave them a straight piece of wire, they would put the wire into a tube and make their own hook then flip that hook around and use the hook to pull the bucket  out of the tube which is really quite remarkable.