Rooks appear to have a better understanding of how gravity works than do chimps and babies under 6聽months old.
A common way of finding out whether animals and babies understand complex concepts is to show them images of impossible events. The rationale is that viewers spend longer looking at those which defy their expectations, presumably as they try to work out what鈥檚 going on.
Chris Bird of the University of Cambridge and of Queen Mary, University of London, showed rooks computer-generated images, half of which were impossible according to the laws of gravity, such as an egg floating in mid-air above a table. Almost without exception, the rooks spent more time looking at the 鈥渋mpossible鈥� images than the possible ones. They also took more second glances.
Advertisement
The responses were the same when the 鈥渇amiliar鈥� egg shape was replaced by a cork, proving the birds鈥� insight applied equally to any object, familiar or not. The researchers say the result is consistent with rooks being able to solve complex problems from knowledge of cause and effect, rather than by trial and error.
Chimp beaters
鈥淭he results illustrate the richness of the information processing underlying bird behaviour, and especially corvid behaviour,鈥� says Alex Kacelnik, who studies corvid intelligence at the University of Oxford. 鈥淭he team used a very elegant procedure to detect whether rooks form expectations regarding the action of gravity.鈥�
But Kacelnik said he was surprised that chimpanzees 鈥渇ailed鈥� the same test. 鈥淚t could be that chimps may respect gravity but fail to infer its presence in a virtual scene between external objects, but I also find this a striking inability,鈥� he says.
In other recent experiments, researchers have shown that crows can use simple tools in sequence to obtain food rewards, and can even use tools in the wild. They鈥檝e also shown their ability to use tools to stop rewards falling into a hole, something great apes were unable to master.
Rooks, meanwhile, can collaborate together to solve problems, and scrub jays appear to be able to undertake 鈥渕ental time travel鈥�.
Journal reference:
