What beaver dams can teach us about surviving a heat wave

What beaver dams can teach us about surviving a heat wave

During an intense heat wave, people have a number of tools to keep cool, such as air conditioning, swimming pools and ice. Wild animals, meanwhile, have beavers.

Yes, beavers. These thick-tailed web-footed amphibious rodents help countless other critters survive a heat wave. Not only do they soak certain landscapes in cold water, but they also help cool the air. They even ensure that forests and grasslands burn less quickly.

This is especially important now. In the past two weeks, a stifling heat wave has burned much of the US and Europe, endangering both people and wildlife. The UK had its hottest day on record. In parts of Oklahoma and Texas, temperatures rose to 115 degrees. And there are still two months of summer to go.

A beaver in Wyoming chews through a tree.
Troy Harrison/Getty Images

While beavers were once hunted to near extinction in North America and parts of Europe — and they are still considered pests by some — it’s becoming increasingly clear that these animals help protect ecosystems from the wrath of climate change. Beavers are true nature heroes in a warming world, and we would be wise to follow their lead.

Beaver dams help cool the water — and the air

The fact that most people know about beavers is that they build dams. But these structures are more than just a pile of sticks laid in a stream. They are hydrological wonders.

Dams form ponds, widen rivers and create wetlands, forming all kinds of aquatic habitats that many other animals such as birds and frogs rely on. This is why beavers are often referred to as ecosystem engineers.

A beaver dam in Wyoming’s Grand Teton National Park.
Moelyn Photos/Getty Images

More than just dispersing water, beavers also help cool it.

Dams can deepen streams and deeper water layers are usually cooler. As streams enter these structures, they can begin to dig into the riverbed, according to Emily Fairfax, an ecology and hydrology expert at California State University’s Channel Islands. So there could be, say, a two-meter-deep pool behind a three-meter-high beaver dam, she said.

Dams also help push cold groundwater to the surface. Dams, made of sticks, leaves and mud, block water as it flows downstream, forcing some of it to travel underground, where it mixes with colder groundwater before resurfacing.

“That’s very important for many temperature-sensitive species like salmon and trout,” says Fairfax.

In a recent study, scientists moved 69 beavers to a watershed in northwest Washington state, and found that their dams cooled streams by more than 4 degrees Fahrenheit (2.3 Celsius) on average during certain times of the year. Another study, published in 2017, saw similarly large drops in temperature after beavers built dams.

A beaver building dams in Denali National Park, Alaska.
George Lepp/Getty Images

Remarkably, beavers can also help cool the air.

“If you’re near a beaver pasture, pretty much anywhere, it’s going to be a lot cooler,” said Christine Hatch, an associate professor at the University of Massachusetts Amherst.

When all that water in a beaver habitat begins to evaporate, the air cools. That’s because converting water to vapor requires energy, and some of that energy comes from the heat in the air, Fairfax said. (This is how swamp coolers, or evaporative coolers, work; it’s also the same reason sweating cools the body.)

“It’s like an AC system sitting there in the landscape and keeping the air temperature, you know, 10 or 15 degrees cooler — which can make a big difference,” Fairfax said.

By flooding land with water, beavers can also create fire breaks

Intense heat waves can also fuel other problems such as drought and wildfires.

Beavers, again, can help.

There is one distinct advantage of beaver dams flooding the landscape with water: wet things don’t burn as easily. “The plants are effectively irrigated year-round,” said Fairfax, who led a study published in 2020 that found areas full of beaver dams are “relatively unaffected by wildfires,” compared to similar but damless habitats.

By drenching the soil and plants with water, beaver dams can help prevent vegetation from burning during a wildfire.
Fairfax and Whittle, 2020/Ecological applications

“Beaver dams play an important role in protecting riparian states [i.e., river-adjacent] vegetation during wildfires,” Fairfax and her co-author wrote in the study, titled “Smokey the Beaver.”

During wildfires, areas of beaver dams can essentially act as “a haven for absolutely any critter that can get in there,” Hatch said.

And it’s not just fires. Beavers also provide drought insurance, by helping to replenish the groundwater that people rely on, Hatch said. Their dams generally slow water flowing downstream, allowing it to seep deep underground, where it’s less likely to dry up.

(By slowing the flow of water, beavers also help reduce the severity of flooding — yet another natural disaster that can exacerbate climate change.)

What a beaver can teach us about resilience

So beavers are damn awesome. Simply living their best lives – damming streams with their cute little hands and powerful buck teeth – they help so many critters around them. We should all be more like beavers really.

A beaver in the Canadian Rocky Mountains.
Jillian Cooper/Getty Images

We can also learn from them. As the ongoing heatwaves have shown, our built environment cannot withstand the effects of climate change. Roads and railways literally nod. We need to make our cities and towns much more resilient, not unlike a habitat full of beaver dams.

And these animals can help as we try to adapt to a warmer world, Fairfax said. “We’re not alone on this planet,” she said. “We don’t have to engineer solutions ourselves.”

Rather than relying solely on man-made technologies and infrastructure, we can also restore species such as beavers to the landscape. “They’re there and we can definitely take advantage of that,” Fairfax said, although it “requires working with nature — rather than constantly working against it.”

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