Thursday, August 16, 2007
No birdbrains here
I ran across this fascinating article today- BBC NEWS | Science/Nature | Cleverest crows opt for two tools.
It discusses the New Caledonian crow, a bird whose toolmaking and tool-using skills put even the great apes to shame. These clever birds recognize the need for a tool, then manufacture it in order to get the specific job done. They also realize which tools are best for which job. In the research described in the BBC article, the birds were presented with a short stick, a long stick in a cage, and a piece of meat in a Plexiglas box which could not be reached with the short stick. On the first trial, four out of six birds tested immediately picked up the short stick, used it to fish out the long stick, and then used the long stick to get the meat out of the box. There are incredible videos of the crows at work.
In other experiments, the crows bent wire into hooks that they used to retrieve small buckets of food from a pipe, and showed that they had a preference for using tools on one side or the other of their beaks.
In the wild, the birds fashion tools from the leaves of the pandanus (screw pine) tree, which have serrated edges. They carefully snip out sections of leaf- wide, narrow, or skillfully-crafted "stepped" tools that taper- and use them to extract grubs from holes. They also make hooked tools by whittling small branches- there is video of this process at the same link as above.
The videos are amazing not just for the skill of the birds, but their obvious attention to detail. In the film of the crows making hooked tools, we see them eye candidate twigs from every angle, then stop frequently while fashioning the hooks to check their progress. There is obviously much more going on here than simple instinct.
These crows are, of course, the object of much scientific study. One of the most intriguing theories being examined is the the crows have a toolmaking culture, where young crows have an inborn propensity for tool use which is developed by watching older crows. Older crows develop better tools and then pass the skill on to younger crows. Researchers believe that the "stepped" pandanus-leaf tools came about in this fashion.
Why are these crows so smart? Research is focusing on that now. It may be that the same evolutionary method is at work here as with keas- extreme generalization. It may also be that these crows are just good tool-users and not so smart in other areas. The researchers are hoping, as they put it, "to test between the adaptive specialisation and general intelligence accounts of the evolution of complex cognition." Studying crows may help us learn how we evolved intelligence as well.