This is a post from Guest Author Randall Johnson, who has contributed a number of guest posts and comments to this blog.
Reconnecting with nature may take some unexpected twists and turns along the way, but who would have thought Aesop’s Fables would turn out to one of them? That’s right. The ancient Greek story-teller credited with collecting such timeless fables as “The Tortoise and the Hare” and “The Boy Who Cried Wolf”, each with a moral lesson at the end, may also have been a keen observer of bird behavior.
In “The Crow and the Pitcher”, a thirsty crow comes across a pitcher with water at the bottom, beyond the reach of its beak. After failing to push the pitcher over, the crow drops in pebbles, one by one, until the water rises to the top, allowing the bird to drink. (The moral of the story: Necessity is the mother of invention.)
Well, it turns out that this is more than just an old fable. Researchers Christopher Bird of the University of Cambridge and Nathan Emery of Queen Mary University of London have reported in the current issue of Current Biology that rooks, another corvid and a relative of the crow, are able to use stones to raise the level of water in a plastic container to reach a floating worm.
Bird and Emery experimented on four rooks by presenting them with a clear tube partly filled with water and a worm floating on top, and a nearby pile of stones of varying sizes. The birds spontaneously dropped stones into the water and seemed to estimate how many stones would be needed. They also quickly learned bigger stones worked better than smaller ones.
Although some species of crows have been proven to use tools in the wild, rooks do not. They don’t have to as they have easy access to food, like carrion. But in an experimental situation like this one, they easily figured out how to use the stones to reach the worm.
Says Mr. Bird, “It was a remarkable combination of some understanding of the task with really rapid learning.” In the summary of their published paper, Bird and Emery state, “This behavior demonstrates a flexible ability to use tools, a finding with implications for the evolution of tool use and cognition in animals.”
The more we take time to watch animals, the better we see how much we share in common with them, including brain power, and how this common thread firmly and solidly connects us to the natural world that supports us all.
Now, I seem to recall Aesop also told a story about the goose that laid golden eggs. Well, if such a fabled fowl should also exist and find its way to my door, that’s one story you won’t read about in Current Biology. I’ll keep that one all to myself.