On Michigan’s Isle Royale, scientists have a rare chance to study a simple food chain at work.

At the bottom of this food chain, there are several kinds of plants. They store energy from sunlight as food. Herbivores (plant eaters) are in the middle of the chain. They get their energy by eating the plants. These herbivores include 1,000 to 2,000 moose, which eat most of the plants.

At the top of the food chain are carnivores, which get their energy by eating meat. On Isle Royale, the only carnivores are 25 to 50 wolves. Their diet is mainly moose. In most wild habitats, the food chains are hard to understand. Usually, several chains are tangled together. In these food “webs,” two or three kinds of meat eaters may live off several types of plant eaters, which may feed on many kinds of plants. Compared to food webs, Isle Royale is a simple laboratory set up by nature.

For 25 years, Dr. Rolf Peterson has been studying this habitat. He is a wildlife ecologist at Michigan Tech University. By flying over the island in an airplane, he and other scientists watch and count the animals. Scientists hope to understand the complex systems of food chains called food webs. But first, they have to learn more about simple food chains, partly by studying the wolves, moose, and trees that live on Isle Royale.

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