Caution: Ingenious animals at work
We used to think that humans were the only tool-users. But now chimps, crows - even dolphins - have been spotted using them.
How often do you use tools? Every day? If you're thinking of a hammer or saw, you might say you don't use tools very often. But a tool can be any object you use to get something done. A fork is a tool. So is a pencil. We use tools all the time. People used to think this was one way we humans were different from animals, because animals don't use tools. Then scientists began to discover animals using tools, sometimes in very clever ways.
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Because animals in captivity were easier to watch than those in the wild, people first observed tool use by zoo animals. They noticed that chimpanzees would pick up a stick and wave or throw it at another chimp to frighten or startle it. Sometimes they used sticks to play games such as tug of war. Scientists decided to study chimps' ability to use tools.
In the 1920s, German-American psychologist Wolfgang Kohler worked with four chimps named Chica, Grande, Konsul, and Sultan. He would place a bunch of bananas out of reach and leave items that could be used for tools, such as sticks and wooden boxes. Soon the chimps figured out how to use the sticks to pull the bananas into their cage, or stack up boxes to reach the bananas. As Dr. Kohler and other scientists observed animals learning to use tools, they wondered if this was something only done in captivity.
Jane Goodall, considered the world's expert on chimpanzees, discovered that the animals also use tools in the wild. She watched chimps at Lake Tanganyika in Tanzania, Africa. Dr. Goodall saw them pick blades of grass and carefully trim them, then stick them into a termite mound for a moment. Then they pulled out the blades covered with termites, one of their popular dinners. They were using the blades as tools to "fish" for their food.
Later observers learned that chimpanzees also clean themselves with wads of leaves, or use them like a sponge to soak up water for drinking. Recently scientists in the Republic of Congo placed cameras in an area frequented by chimpanzees, to observe them when no humans were around.
The cameras recorded the chimps using a tool kit, a combination of tools, to get their termite dinners out of underground nests. The chimps use their feet to poke a large stick into the earth, as you might push a shovel into the ground to dig a hole. Then they use a different stick as a fishing probe to bring out the termites. Sometimes they even use their teeth to fray the end of the probe, like a brush, to collect more insects.
The chimps seem to know that different types of sticks work best for different purposes. They use a specific plant for each tool. They gather the sticks from one area and carry them to places where termites are found.
Chimps aren't the only animals to use tools. Orangutans have been seen braiding vines together to make stronger rope. Capuchin monkeys use rocks to smash open palm nuts.
Even birds have uses for tools. Woodpecker finches and green jays also use a probe (a cactus spine or twig) to pull grubs and insects from holes in trees.
Another bird, the Egyptian vulture, likes to dine on ostrich eggs. The eggs are too hard to break open by pecking them with their beaks. Goodall also observed these birds in Tanzania. She found that the vultures throw rocks at the eggs to break them open.
Green herons have been seen to use bait when they go fishing. The heron drops a small object onto the surface of the water. Sometimes this brings fish to the surface. The fish think the object is food. Then the heron snatches the fish for its dinner.
Not all green herons do this. Scientists are still trying to understand how the birds learn this and why only some birds do it.
