Nature's Engineers

Beavers are often viewed as nuisances. That’s because the bucktoothed rodents build dams in streams, causing water to back up. This can flood farmland, yards, and roads. But more and more people are realizing beaver dams aren’t necessarily a bad thing. They’re an important part of North America’s ecosystem—a community of organisms interacting with their environment.

Emily Fairfax is an ecohydrologist at California State University Channel Islands. She studies how beavers alter the flow of water and how that can affect ecosystems. “Beavers are a keystone species,” says Fairfax. “A lot of other species depend on them in order to survive. Without beavers, other species have a really hard time.” That’s because beaver ponds provide these animals with homes and food.

Fairfax has found that beaver dams also greatly reduce an ecosystem’s wildfire risk. By flooding an area, beavers make surrounding soil damp and fertile, causing vegetation to grow. These conditions make an area resistant to burning.

Beaver dams help the environment on a large scale too. Smoke from wildfires contains greenhouse gases. They trap heat in the atmosphere, leading to an increase in the average global temperature on Earth—worsening climate change. By lowering wildfire risk, beavers help fight climate change, explains Fairfax. The soil and plant life around beaver ponds further lessens warming by absorbing greenhouse gases.

Fairfax says that because beavers play such vital roles in ecosystems, people should find ways to coexist with the animals.

People often view beavers as a problem. The bucktoothed rodents build dams in streams, and that causes water to back up. This can flood farmland, yards, and roads. But more and more people are changing their minds about beavers. They realize that beaver dams aren’t necessarily a bad thing. These dams are an important part of North America’s ecosystem. That’s a community of organisms along with their environment.

Emily Fairfax is an ecohydrologist at California State University Channel Islands. Beavers change the flow of water, and that can affect ecosystems. Fairfax studies how this happens. “Beavers are a keystone species,” she says. “A lot of other species depend on them in order to survive. Without beavers, other species have a really hard time.” That’s because beaver ponds provide homes and food for these animals.

Fairfax has found another benefit of beaver dams. They greatly reduce an ecosystem’s wildfire risk. By flooding an area, beavers make surrounding soil damp and fertile. That causes vegetation to grow. As a result, the area is resistant to burning.

Beaver dams help the larger environment too. Smoke from wildfires contains greenhouse gases. They trap heat in the atmosphere. That increases the average global temperature on Earth and worsens climate change. But beavers lower wildfire risk. In that way, they help fight climate change, explains Fairfax. And the soil and plant life around beaver ponds absorb greenhouse gases. That also lessens warming. Because beavers are so important to ecosystems, people should find ways to coexist with them, says Fairfax.

To build a dam, beavers pile rocks, sticks, and mud across a stream. The flowing water backs up behind the dam to form a pond. Beavers monitor their dam walls for leaks and make repairs. The longest known dams stretch for thousands of feet.

To build a dam, beavers pile rocks, sticks, and mud across a stream. The flowing water backs up behind the dam to form a pond. Beavers monitor their dam walls for leaks and make repairs. The longest known dams stretch for thousands of feet.

A beaver pond can cover an area as small as 1 acre. The largest ponds can span 100 acres—about as big as eight football fields.

A beaver pond can cover an area as small as 1 acre. The largest ponds can span 100 acres—about as big as eight football fields.

Beaver ponds keep surrounding soils damp and fertile. Vast meadows often form near beaver dams. Large animals like moose graze there. These lush landscapes can help slow or even stop fast-moving wildfires.

Beaver ponds keep surrounding soils damp and fertile. Vast meadows often form near beaver dams. Large animals like moose graze there. These lush landscapes can help slow or even stop fast-moving wildfires.

The pond provides habitat for animals like fish, frogs, turtles, and insects. It also attracts birds and other animals looking for food.

The pond provides habitat for animals like fish, frogs, turtles, and insects. It also attracts birds and other animals looking for food.

Beavers construct a lodge within their pond. The home’s protective walls are insulated with mud to hold in heat. A small hole in the roof allows air inside. The floor is covered in wood shavings to absorb moisture. Entrances are underwater, which helps keep out unwanted visitors.

Beavers construct a lodge within their pond. The home’s protective walls are insulated with mud to hold in heat. A small hole in the roof allows air inside. The floor is covered in wood shavings to absorb moisture. Entrances are underwater, which helps keep out unwanted visitors.