The work is reported by Amanda Seed and Nicola Clayton and colleagues from the University of Cambridge, and appears in the April 4th issue of Current Biology.
Laboratory studies show that many tool-using species can solve problems such as the so-called trap-tube task, which consists of a horizontal tube with a trap along its length. To solve the task, an animal must use a tool to push a piece of food out of the tube, away from the trap. However, this task can be solved in at least two ways: by using a simple rule based on the position of the food in relation to the trap, or by an understanding of how the task works. Previous studies have found no evidence that animals understand this task.
In this new study, this classic design was modified to test rooks, a non-tool-using species. A modified trap-like structure was introduced, one that would not trap the food. The study found that these birds are capable of rapidly learning the task. The researchers then changed the appearance of the traps to test whether the rooks actually understood the task. For example, in one task the non-functioning trap was bottomless, allowing food to fall through. In a so-called transfer test, the food could pass over the top.
If the birds' solution was based simply on the arbitrary appearance of the task, they should have failed these transfer tests. However, the results suggested that these birds have the capacity for physical cognition. Exactly what the rooks understand about the tasks--for example, whether they are able to solve physical tasks by using "rule abstraction" --is an exciting question for future research.
Amanda M. Seed, Sabine Tebbich, Nathan J. Emery, and Nicola S. Clayton of the University of Cambridge in Cambridge, United Kingdom. The work was funded by the BBSRC, the Royal Society, and the University of Cambridge.
Seed et al.: "Investigating Physical Cognition in Rooks, Corvus frugilegus." Current Biology 16, 697-701, April 4, 2006 DOI 10.1016/j.cub.2006.02.066. www.current-biology.com