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It’s no accident that both the  and the  claim the beaver (Castor canadensis) as their mascots. Renowned engineers, beavers seem able to dam any stream, building structures with logs and mud that can flood large areas. 

As climate change causes extreme storms in some areas and intense drought in others, scientists are finding that beavers’ small-scale natural interventions . In dry areas, beaver ponds restore moisture to the soil; in wet zones, their dams and ponds can help to slow floodwaters. These ecological services are so useful that land managers are translocating beavers  and  to help restore ecosystems and make them more resilient to climate change. 

Scientists estimate that  once dammed waterways across the Northern Hemisphere. They were  in the 18th and 19th centuries in Europe and North America but are  in many areas. As a , I think it’s important to understand how helpful beavers can be in the  and to find ways for humans to coexist with them in developed areas.

How beavers alter landscapes

Beavers , where they can construct their dome-shaped lodges in the water, keeping predators at a distance. When they create a pond, many other effects follow. 

Newly flooded trees die but remain standing as bare “snags” where birds nest. The diverted streams create complicated interwoven channels of slow-moving water, tangled with logs and plants that provide hiding places for fish. The messy complexity behind a beaver dam creates many different kinds of habitats for creatures such as fish, birds, frogs and insects. 

Human dams often  upstream and downstream, even when the dams . But  that fish have no trouble migrating upstream past beaver dams. One reason may be that the fish can rest in slow pools and cool pond complexes after navigating the tallest parts of the dams. 

The slow-moving water behind beaver dams is very effective at trapping sediment, which drops to the bottom of the pond. Studies measuring total organic carbon in active and abandoned beaver meadows suggest that before the 1800s, active and abandoned beaver ponds across North America  in sediment trapped behind them. This finding is relevant today as scientists look for ways to .

Beavers may persist in one location for decades if they aren’t threatened by bears, cougars or humans, but they will move on if food runs out near their pond. When abandoned beaver dams fail, the ponds drain and gradually become grassy meadows as plants from the surrounding land seed them. 

Dried meadows can serve as floodplains for nearby rivers, allowing waters to spill out and provide forage and spawning areas for fish during high flows. Floodplain meadows are  for ground-nesting birds and other species that depend on the river. 

The value of slowing the flow

As human settlements expand, people often wish to make use of every acre. That typically means that they want either land that is solid and dry enough to farm or waterways they can navigate by boat. To create those conditions, humans remove floating logs from streams and install drains to draw water off of fields and roads as quickly and efficiently as possible. 

But covering more and more land surface with barriers that don’t absorb water, such as pavement and rooftops, means that water flows into rivers and streams more quickly. Rainfall from an average storm can produce an intense river flow that . And as climate change , it will amplify this destructive impact.

Some developers limit this kind of damaging flow by using , such as “ponding” water to intercept it and slow it down; spreading flows out more widely to reduce the water’s speed; and designing swales, or sunken spots, that allow water to sink into the ground. Beaver wetlands do all of these things, only better. Research in the United Kingdom has documented that beaver activity can . 

Beaver meadows and wetlands also . Wet soil in these zones contains a lot of organic matter from buried and decayed plants, which holds onto moisture longer than soil formed only from rocks and minerals. In my , I have found that after a storm, water entering the ground passes through pure mineral sand in hours to days but can remain in soils that are 80%-90% organic matter for as long as a month. 

Cool, wet soil also serves as a buffer against wildfires. Recent studies in the western U.S. have found that vegetation in beaver-dammed river corridors is  than in areas without beavers because it is well watered and lush, so it doesn’t burn as easily. As a result, areas near beaver dams provide  when .

Making room for beavers

The ecological services that beavers provide are most valuable in zones where nobody minds if the landscape changes. But in the densely developed eastern U.S., where I work, it’s hard to find open areas where beaver ponds can spread out without flooding ditches or roads. Beavers also topple expensive landscaped trees and will feed on some cultivated crops, such as .

Beavers are frequently blamed for flooding in developed areas, even though . In such cases, removing the beavers doesn’t solve the problem. 

, fences and other exclusion devices can keep beavers a safe distance from infrastructure and maintain pond heights at a level that won’t flood adjoining areas. Road crossings over streams that are designed to  are beaver-friendly and will be resilient to climate change and extreme precipitation events. If these structures are large enough to let debris pass through, then beavers will build dams upstream instead, which can help catch floodwaters.

A growing body of research shows that setting aside pockets of land for beavers is good for wetland ecosystems, biodiversity and rivers. I believe we can learn from beavers’ water management skills, coexist with them in our landscapes and incorporate their natural engineering in response to weather and precipitation patterns disrupted by climate change.