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NGSS: Core Idea: ESS2.C

CCSS: Reading Informational Text: 7

TEKS: Science: 3.9A; 4.10A; 5.9A; 6.12E; ELA: 3.6B; 4.6B; 5.6B, 6.5B

Very Busy Beavers

 Why scientists are bringing these rodents back to the streams where they once lived

Page 4: Jeff Foott/Minden Pictures

A beaver uses its long, curved teeth to chew through a fallen tree in Grand Teton National Park in Wyoming.

As you read, think about how beavers affect the environment where they live.

Mike Sevigny hikes to the edge of a muddy pond north of Seattle, Washington. He and a team of scientists lower a metal cage smeared with beaver scent into the water. This smell attracts other beavers. If one of the curious critters swims inside the cage and its feet hit a wire, a door swings shut. 

Sevigny is the wildlife manager for the Tulalip Tribes, a group of Native American tribes in northwestern Washington. Over the past six years, he and his team have captured about 300 beavers and moved them to different streams. It’s part of an effort to restore wetlands in the area. Caring for nature is a part of the tribes’ cultural heritage.

Mike Sevigny is hiking with a team of scientists. They’re just north of Seattle, Washington. They stop at the edge of a muddy pond. Sevigny lowers a metal cage into the water. The cage is coated with beaver scent. This smell attracts other beavers. The critters are curious. One follows the scent into the cage. Its feet hit a wire. The cage’s door swings shut.  

Sevigny is a wildlife manager. He works for the Tulalip Tribes. It’s a group of Native American tribes. Their people live in northwestern Washington. Sevigny’s team has captured about 300 beavers over the past six years. Then the team moves the animals to different streams. It’s part of an effort to restore wetlands in the area. Caring for nature is important to the tribes. It is part of their cultural heritage.

Arterra/Universal Images Group via Getty Images (lodge & dam photo)

Beavers are the largest rodents in North America. An adult can weigh 30 kilograms (65 pounds)—about as much as a golden retriever! Beavers use long, curved teeth to gnaw on tree trunks and branches. They eat the bark, then use sticks and mud to build dams across streams or rivers. 

Beavers once lived all over North America. But in the 1700s, French and British colonists began trapping the rodents across Canada and the U.S. They used the animals’ pelts to make hats. By 1900, millions of beavers had been killed. 

Today, many people are trying to bring beavers back to places where they once lived. That’s because the presence of beavers can benefit a stream in many ways. “I don’t know what other animal can build up the ecosystem better than a beaver,” says Sevigny.

Beavers are rodents. They’re the largest ones in North America. An adult can weigh 30 kilograms (65 pounds). That’s about as much as a golden retriever! Beavers have long, curved teeth. They use them to gnaw on tree trunks and branches. The beavers eat the bark. They also use the wood along with mud to build dams. They’re built across streams or rivers. 

Beavers once lived all over North America. Then French and British colonists arrived in the 1700s. They began trapping the rodents. This happened across Canada and the U.S. Colonists used beaver fur to make hats. Millions of beavers had been killed by 1900.

Today, people are trying to bring the animals back. They want beavers to return to where they once lived. That’s because beavers can help streams in many ways. “I don’t know what other animal can build up the ecosystem better than a beaver,” says Sevigny.

Eager Engineers

A beaver dam is a marvel of engineering. The animals carefully arrange their materials to block almost every part of a stream (See Inside a Beaver Lodge). Soon, the nearby landscape changes. The flow of water slows to a trickle. Over time, the water builds up to form a pond. The pond helps beavers stay safe from predators. It also provides habitat for fish, frogs, and other animals. 

The beaver pond helps the environment in other ways too, says Ellen Wohl. She’s a geologist who studies rivers at Colorado State University. Water flows into the pond quickly but takes much longer to flow out through the dam. This filters pollution, making the water safer for people and animals downstream. Slowing the flow of the river can also reduce the risk of flooding when it rains. 

The sediment beneath the pond also soaks up water. “A beaver pond is like a big sponge,” says Wohl. This stored water seeps out and feeds the stream all year. Streams without beaver dams can go completely dry in the summer!

A beaver dam is an engineering feat. The animals carefully place their materials. They block almost every part of a stream (see Inside a Beaver Lodge). Soon, the area changes. The stream’s flow slows to a trickle. Its water builds up on one side of the dam. It forms a pond over time. The pond helps beavers stay safe from predators. It also creates habitat. Fish, frogs, and other animals make homes in the pond.

The beaver pond helps in other ways too, says Ellen Wohl. She’s a geologist. She studies rivers. She works at Colorado State University. Water flows into the pond quickly. But it takes much longer to flow out through the dam. This helps remove pollution. The filtered water is safer for people and animals downstream. The dam also helps when it rains. It slows the river’s flow. So, there’s less risk of flooding.

The bottom of the pond contains sediment. It soaks up water. “A beaver pond is like a big sponge,” says Wohl. This stored water slowly seeps out. It feeds the stream all year. Streams without beaver dams can go totally dry in the summer!

Living With Beavers

Over the past century, beavers have made a comeback. But many people consider them pests. That’s because beavers sometimes build dams across roadside drainage pipes, causing the water to spill into roads. Overflowing beaver ponds can damage farms and homes. 

When that happens, wildlife scientists often step in to help. They might put up fencing to keep beavers away or find other ways to control the water level in a beaver pond. But sometimes these efforts fail. That's when scientists like Sevigny move the rodents to a stream where they can do some good.

Beavers have made a comeback over the past century. But many people think they’re pests. Beavers sometimes build across roadside drainage pipes. Their dams cause the water to spill into roads. Overflowing beaver ponds can damage farms and homes. 

Wildlife scientists often step in to help when that happens. They might put up fencing around an area. It keeps beavers away. Scientists might also find ways to control a beaver pond’s water level. But sometimes these efforts fail. That’s when scientists like Sevigny move the rodents. They’re taken to a new stream. There, they can do some good.

On the Move

People started relocating beavers in the late 1940s. The first ones were flown over forests and dropped from planes with parachutes! Today, Sevigny’s team moves beaver families by car to streams where beavers haven’t lived in a long time. 

The beavers quickly get busy building their new homes. Over the next few years, Sevigny’s team checks on the animals using hidden cameras or drones. “We can see how what started out as a simple stream has been changed by the beavers,” says Sevigny. “They’re incredible critters, and they work for free.”

People started moving beavers in the late 1940s. The first ones were flown over forests. Then they were dropped from planes with parachutes! Today, Sevigny’s team moves beaver families by car. They’re driven to new streams. They’re ones where beavers haven’t lived in a long time. 

The beavers quickly get busy building new homes. Sevigny’s team checks on the animals for a few years. The team uses hidden cameras or drones. “We can see how what started out as a simple stream has been changed by the beavers,” says Sevigny. “They’re incredible critters, and they work for free.”

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