Think of a crow. Your mind inevitably turns to its sharp, black beak pecking at your eyeballs when you die. The scavenger has dominated popular culture: where there are crows, there is death. No panoramic view of a battlefield would be complete without crows. There’s a reason their collective name is “a murder”.
But it seems there is more to our general fear of crows. They are very clever. In the past decade, research has proved crows punch way above their size in the brain stakes.
Research from Sweden’s Lund University – released this week – gave wings to the idea that crows are vastly cleverer than their peers. Students took a collection of ravens, jackdaws and New Caledonian crows and put a tasty treat for them in an opaque tube with holes at each end. The birds went to the ends and climbed in to get food.
The team then placed the treat in a transparent tube. With basic instinct, most of the birds tried to get through the glass to the food. They failed.
But nearly 100% of the crows walked to the end of the tube before going in and finding food.
This is a big departure from the behaviour of most animals. Inhibitory control – the ability to override impulses in favour of rational behaviour – is something only intelligent species exhibit.
Previous research at Duke University in the United States did the same test with 36 different animal species. This found that primates and apes had strong inhibitory control, which its researchers concluded was proof that bigger brains meant more intelligence in nature.
In 2002, research from Oxford University found that crows could use tools to find food. In nature, crows use twigs to get at food that they cannot reach with their beaks. But in the laboratory, a female crow – Betty – consistently took straight pieces of wire and bent them to get at pieces of her favourite food, pig heart. This was the first time a non-primate species had been found to use tools that they had created.
The team said: “The surprising thing about our crow is that, faced with a new problem, she worked out a new solution by herself.”
Cambridge University released research in 2004 saying that crows use their imagination to anticipate possible future events. This allows them to think through the different solutions to a problem, and to work well as a society, planning together at a level otherwise only seen in dolphins, chimpanzees and humans. But they all have much larger brains.
The proof of crows’ intelligence is not confined to university campuses. In nature, crows are regularly found sitting on ant nests while ants douse them in formic acid. This is the nest’s defence mechanism, but it also kills the parasites that stick to crows’ legs.
The Lund findings prove that brain density is as important as size. It also goes one step further in conclusively proving what humans have known for a long time: crows are capable of all sorts of ingenuity.