Smart Crows!

Some crows have learned that it's important to use the right tool for the job. For example: if you're hungry and want a tasty beetle larvae tucked inside a tree trunk, the right tool would be a stick. You hold the stick on your beak and poke it into the hole where there's a beetle grub. That irritates the beetle larvae which snaps its jaws tight on the stick. Then all a crow has to do is pull it out.

But what if food is in a small bucket with a handle? And it's stuck in a tube? A stick won't work - but a piece of wire might. In 2002 some scientists gave a female New Caledonian crow a bit of wire and that very problem She bent the wire into a hook that allowed her to grab the bucket handle and retrieve the food. She did it not once, but nine times in the subsequent ten trials.




Now, scientists in New Zealand have shown that crows can solve puzzles to get food. They offered crows food that was floating on top of water in tubes. The problem: the tubes were narrow, so only their beak fit in. And the water level was so low the crows couldn't reach the food. Fortunately, the scientists provided the crows with an assortment of blocks and other heavy items. The crows figured out that if they dropped the blocks in the tube they would displace the water, raising the food to a level where they could reach in and grab it with their beaks.




Crows aren't the only birds to use tools. The Woodpecker Finch (Galapagos Islands) uses a cactus spine to dig grubs out of holes. Egyptian vultures drop stones on ostrich eggs to break them. And some herons use breadcrumbs or insects as bait to lure fish into reach.

Are there any tool-using animals in your neighborhood? Drop by STEM Friday to see what other science books and resources bloggers are sharing.