Tool use comes naturally to crows
Certain crows appear to be born with an instinct to make and use tools.
You probably use tools all day long without even thinking about it. You pick up a pencil to write. You deliver food to your mouth with a fork or spoon. You use keys to open doors. And you probably learned most of these skills when you were little.
Crows, it seems, can learn to use tools without any help at all. A new study has found that the birds can use sticks to get food, even when nobody teaches them what to do. It’s the first clear example in vertebrates (animals with backbones) showing that tool use is an instinct that some animals are born with.
A hand-raised young crow uses a twig to poke food out of slot without ever having seen the trick before.
The researchers, who are from the University of Oxford in England, knew that certain birds, such as woodpecker finches, burrowing owls, and New Caledonian crows, often make and use tools. What they wanted to find out was whether a young bird learned to use tools by watching others, or if they were born with the skill.
Scientist Benjamin Kenward took on the project after some New Caledonian crows were brought to England to start a breeding colony. The crows had trouble incubating their eggs, so Kenward moved the eggs to an incubator—a machine that keeps them at the right temperature. After the eggs hatched, he became a surrogate parent to four of the little chicks.
Kenward gave up much of his normal life for months to take care of the birds. Several times a day, he gave two of the little crows twig lessons by showing them how to drag sticks through crevices to get food. Kenward did not give lessons to the other two crows, and they were not allowed to watch him work with the first two.
Nevertheless, all four crows figured out how to use tools. The birds that were not given lessons, for example, picked up sticks and poked them at food placed inside little slots.
One young crow even made a tool of his own. The researchers put long, strong leaves in the birds’ cages. This crow ripped a strip off a leaf and used the strip to poke food out of hard-to-reach places. Wild crows do the same sort of thing, but their strips tend to have fancier edges.
Still, even though tool use appears to be instinctive, scientists say, teaching might be important for learning better ways to do something. We may have an instinct to put things in our mouth, but we learn from Mom how to do it neatly with a fork or chopsticks.
Milius, Susan. 2005. Crow tools: Hatched to putter. Science News 167(Jan. 15):38. Available at http://www.sciencenews.org/articles/20050115/fob7.asp .
Sohn, Emily. 2003. Better tools for techno crows. Science News for Kids (March 26). Available at http://www.sciencenewsforkids.org/articles/20030326/Note3.asp .
For movies of tool use by crows, go to users.ox.ac.uk/~kgroup/tools/ontogeny.html (University of Oxford).
For more on New Caledonian crows in the wild, go to www.psych.auckland.ac.nz/Psych/research/Evolution/Gavin.htm (University of Auckland).