Crows are capable of using multiple tools in complex sequences, the first time such behaviour has been observed in non-humans, scientists have found.

A study at Oxford University suggests that the birds are capable of a level of logical thinking, forward planning and creativity only normally associated with people. Scientists say the work calls for a rethink on the underlying mechanisms governing animal behaviour.

In the study, details of which are published today in the journal PLoS One, crows were able to use tools in a precise sequence that culminated in them obtaining out-of-reach food. Crucially, they were able to complete the task without any special training.

“There’s something uncanny about the way these animals do it,” said Alex Kacelnik, a zoologist at the University of Oxford who led the research.

Chimpanzees and other non-human primates are known to be capable of using tools sequentially, but have to be explicitly trained to do so.

Seven New Caledonian crows were given the task of using three different lengths of stick to retrieve a reward — a small piece of pig’s heart. This was placed out of reach at the end of a transparent tube such that it could only be reeled in with a long stick.

Starting with a short stick, the crows had to first pull a medium stick towards them, and then in turn use that one to obtain the longest stick.

Five of the crows completed the task successfully and four of them did this on their first attempt.

Animal behaviour is usually explained as a series of trial and error events, whereby animals do things at random and then repeat an action if it is rewarded. However, the complexity of the task suggests that the birds could not arrive at the correct solution simply by chance.

Professor Kacelnik says the crows behaviour had a lot in common with the way children learn. By watching others and experimenting crows build up a repetoir of strategies that they can recall and use in the future.

“They demonstrate flexible behaviour, creativity, and inventiveness - all things we normally associate with human intelligence,” said Professor Kacelnik. However, he added, it is impossible to know to what extent conscious decisions directed the crows’ actions. “The only way we have of getting inside the mind of an animal is through observing their behaviour,” he said.

Crows have an innate propensity for tool use, scientists have found, and will attempt to use sticks and wires to obtain food even if they are raised in isolation. However, young birds become more adept at deploying tools if they are able to observe how adult birds use them.

In a previous study by the Oxford team, a crow named Betty was able to invent new tools by bending strips of metal into hooks or straightening them to reach further, depending on the task. However, the tools were always used directly to access food. Using tools on non-food items, as the crows did in the latest study, is generally viewed as a mark of higher intelligence.

Supporting the idea that crows are among the most intelligent of birds, they have a particularly high brain-to-body-mass ratio. New Caledonian crows weigh about half as much as a common pigeon, but their brain is about twice the size.

Crows have long been associated with intelligence in folklore. In the Aesop fable, The crow and the pitcher, a thirsty crow comes across a jug with water at the bottom, beyond the reach of its beak. After failing to push over the pitcher, the bird comes up with a clever solution: it drops pebbles into the pitcher one by one until the water rises to the top allowing it to drink.

An American inventor, Joshua Klein, is trying to harness crows’ capabilities for social purposes, specifically clearing up litter. He is developing a crow vending machine that would give a reward in exchange for the litter, which he thinks the birds could learn to use.

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