They may be popularly considered to be 'bird-brained' but crows are actually better at physical reasoning than our primate cousins, scientists say.
New Caledonian crows are famous for their ability to make complex tools out of twigs and leaves. Now scientists believes they are more able than apes when finding a way to access food without it falling into a trap.
Scientists at the University of Auckland presented crows with a trap-tube puzzle. In this task the birds had to extract food from a horizontal tube in a direction that avoided a trap.
When the crows were presented with variations of the problem where arbitrary cues were removed, the crows continued to solve the problem. This suggested the crows had not simply learnt how to solve it through association.
The scientist then presented the crows with a trap-tube with two holes. One hole was bottomless, allowing food to fall through it and out of the trap. The other hole had a base and so trapped food that was pulled into it.
The crows failed to consistently solve this problem and appeared reluctant to pull the food into either hole. This suggested the crows were using the position of the hole to guide their actions.
Finally, the crows were presented with a trap-table puzzle. In this problem an animal has to choose between pulling food across a wooden table or pulling food into a hole set in the table.
In a recent study 20 individuals from the great ape species were unable to transfer their knowledge from the trap-table and trap-tube or vice versa, despite the fact that both these puzzles work in the same way.
Strikingly the crows in The University of Auckland study were able to solve the trap-table problem after their experience with the trap-tube.
By solving the trap-table the crows demonstrated that they had not just learnt to pull away from the specific hole in the Perspex trap-tube, but could generalise what they understood to a novel problem.
'The crows’ success with the trap-table suggests that the crows were transferring their causal understanding to this novel problem by analogical reasoning,' Professor Russell Gray of the Department of Psychology said.
'However, the crows didn’t understand the difference between a hole with a bottom and one without. This suggests the level of cognition here is intermediate between human-like reasoning and associative learning.'
The research by Dr Gavin Hunt and Professor Russell Gray appeared online in the Proceedings of the Royal Society: B
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