National Geographic Magazine July 2024

First, they were pelts, then pests. But now they are emerging as something else: climate heroes.

Could beavers be the secret to winning the fight against wildfires?

By Ben Goldfarb

Photographs by Ronan Donovan and Kholood Eid

PUBLISHED 13 MAY 2025

The East Troublesome fire erupted on October 21, 2020, whipped by strong winds and fueled by drought-parched forests. The fire roared through northern Colorado’s spruce and fir woods; it leaped roads and rivers and the Continental Divide, scaling mountain passes above tree line. It incinerated historic buildings in Rocky Mountain National Park and homes in Grand County, killing two people. Ultimately, it torched nearly 200,000 acres, making it the second largest fire in Colorado’s history.

In the end, just about the only thing the East Troublesome didn’t consume was beaver ponds.

(How wildfires can grow deadly overnight.)

This was not entirely surprising. Beavers, of course, build dams that store water—and water, as you may know, doesn’t burn. But the benefit the semiaquatic rodents provide goes further than that. In a study published weeks before the East Troublesome blew up, Emily Fairfax, an ecohydrologist now at the University of Minnesota, found that beaver ponds and canals irrigate the landscape so thoroughly that they turn crisp, flammable plants into lush, fireproof ones, forming green refuges in which wildlife and livestock can retreat. In a nod to another firefighting icon, Fairfax and her co-author titled their paper “Smokey the Beaver.”

| On Northern California’s Yellow Creek, a nonprofit works with watershed restoration engineers and a member of the Mountain Maidu tribe to build artificial replicas of beaver dams—so-called beaver dam analogs— which create habitat for other animals and saturate the landscape with water.

Photograph by KHOLOOD EID

Fairfax studied five fires between 2000 and 2018 to reach her conclusions. But the East Troublesome was far bigger than most of those blazes—and a harbinger of the kind of conflagration we’re seeing more and more. Although fire has long been a natural force of regeneration on North American landscapes, the so-called megafires that plague the ever drier West are a different matter, stoked by climate change into explosive infernos that burn so big and hot that ecosystems don’t always readily recover. Fairfax doubted whether beavers could still fireproof large tracts of the landscape under those conditions. But when she visited the charred forests left behind by the East Troublesome and one other megafire, she discovered that the oases beavers created with their ponds had endured. “There are entire rivers that are basically unaffected by the fire, because it’s just beaver dams the whole way,” she said. “Everything is full of life: The reeds are growing; the pine needles are still on the trees.” The ponds aren’t merely helpful before a fire—they can also protect ecosystems from the effects that come right after a blaze, capturing the ash and debris that run off hillslopes and shielding downstream fish and drinking water. In a 2024 paper describing their findings, Fairfax and her collaborators concluded that beavers “can be part of a comprehensive fire-mitigation strategy.”

Once hunted to near extinction for their pelts and later villainized as a nuisance, beavers have rebounded. There are now 10 to 15 million swimming and waddling across most of North America, and they’re ready for their third act, cast in an improbable role: ecological saviors to a climate change–ravaged world. And fire mitigation is just the start. By building dams that slow streamflow, they create reservoirs that help combat drought; by sculpting wetlands, they furnish habitat for other animals.

Nowhere is their return more necessary than in the climate-stressed American West, where beaver restoration is unfolding, to some extent, in every state. But beavers, tireless meddlers with a penchant for running afoul of human infrastructure, aren’t yet universally welcome.

(These eager beavers saved the Czech government $1.2 million.)

| A beaver swims back to its lodge underneath the frozen surface of a creek in Bozeman, Montana. Beavers don’t hibernate, so they spend the entire fall stockpiling wood underwater to feed on through the winter.

Photograph by RONAN DONOVAN

The San Pedro River snakes across Arizona’s border with Mexico through the sunblasted Sonoran Desert. Though the arid land seems better suited for rattlesnakes than for semiaquatic rodents, frontiersmen once knew the San Pedro as the Beaver River—before 19th-century trappers stripped it clean. “Anywhere there were perennial waters, there were probably beavers,” Lisa Shipek, the director of a nonprofit called the Watershed Management Group, told me one fall day along the San Pedro’s cobble-strewn banks.

In 1999, in hopes of enhancing the area’s wildlife habitat, the federal Bureau of Land Management restocked the San Pedro with 16 beavers, whose offspring dispersed throughout the river, including into Mexico. Since 2020, Shipek, along with Mexican biologists and legions of volunteers, has been scouring the river to estimate their population. I joined her team for a day of surveying the San Pedro’s shady cottonwood galleries for beavers’ chew marks, tracks, and lodges. Along the trunk of one downed cottonwood, beavers had chiseled away the bark to expose cream-colored heartwood and whittled limbs to blunt points. Pale chips littered the bank. “They were probably here within the last few weeks,” Shipek half-whispered.

It’s easy to empathize with beavers. Like many of us, they live in nuclear families: A typical colony consists of a breeding pair and their offspring, which stick around until the age of two. On land, beavers are clumsy morsels for cougars, wolves, and bears, but they’re balletic swimmers, endowed with transparent eyelids and webbed hind feet. Their keratin-scaled tails serve as fat-storage units and rudders; their iron-reinforced teeth scrape away the inner bark that provides the bulk of their herbivorous diet. By building dams and filling ponds around their woody lodges, beavers expand and defend their aquatic domains, like feudal lords with moats around castles.

Like humans, too, beavers are survivors. Just as Homo sapiens are the last in a long line of hominins, the world’s two beaver species—Castor canadensis, the North American beaver, and Castor fiber, its Eurasian cousin—are vestiges of a diverse family. Their now extinct relatives include Castoroides ohioensis, which grew nearly as large as black bears. Although it’s tempting to imagine Castoroides constructing Hoover Dam–size walls, the species likely didn’t dam at all and died out during drier conditions. Modern beavers may have endured precisely because they could modify nature on a warming planet.

| Beavers on Montana’s Crazy D Ranch harvest a large cottonwood tree to construct dams and lodges.

Photographs by RONAN DONOVAN

As beavers proliferated, they shaped the land. At one time, as many as 400 million of them roamed North America and constructed up to 250 million ponds. Those beaver-built bodies of water bolstered amphibian and salmon populations, supported mammals from muskrat to moose, and aided songbirds, which perch in coppiced willows and eat aquatic insects. Indigenous peoples have long understood beavers’ importance: The Blackfeet environmental historian Rosalyn LaPier notes that the tribe believes beavers are divine animals that can talk with humans and venerates them for the ecological oases they create. But colonists didn’t share that respect. In the 1500s, beaver pelts came into vogue in Europe. They were used for elegant hats, which milliners felted from beavers’ Velcro-like underfur. To meet the demand, fur trappers and traders purged beavers from practically every waterway on the continent. As the animal vanished, wetlands dried up and streams eroded, a cataclysm akin to an aquatic dust bowl.

(Beavers on the coast are helping salmon bounce back. Here’s how.)

Yet beavers weren’t finished. In the early 1900s, many states enacted trapping restrictions and reintroduced beavers from places like Canada and Yellowstone National Park. Some land managers got creative: In 1948 the Idaho Department of Fish & Game packed beavers into crates and dropped them by parachute into the wilderness. Two years later, the Journal of Wildlife Management reported that “beavers had built dams, constructed houses, stored up food, and were well on their way to producing colonies.”

As beavers have slowly returned to the West over the past several decades, their helpfulness has grown more appreciated—just as our climate woes have multiplied. Their ponds store and gradually release rainfall and snowmelt, compensating for dwindling snowpack. By allowing water to seep into floodplains, they also hydrate soils and recharge aquifers. One 2022 study that tracked relocated beavers in Washington State found that the average pond stored more than a quarter million gallons of surface water and over 600,000 gallons of groundwater. “Beavers are slowing the flow, holding on to water longer, and mimicking the function of the depleted snowpack,” said Joe Wheaton, a geomorphologist at Utah State University. “If that isn’t serving a societal need, I don’t know what is.”

In the San Pedro River, Shipek estimates that up to 21 beavers now live on the Arizona side of the border and perhaps 17 more in Mexico—though the populations are divided by a metal floodgate that is part of the border wall. During our survey, we saw ample chew and a few lodges but no dams. Still, Shipek hopes that beavers could someday restore the bountiful wetlands that long ago prevailed in many desert watercourses—and help the Southwest address its water woes.

“I can only imagine how different it would have looked,” Shipek said wistfully as we waded through the shin-deep flow of the former Beaver River, envisioning the ponds and marshes that once shimmered here. “It just seems so important to bring back this critical species. It’s the evolution of restoration in this area.”

| A beaver lodge is part of a neighborhood in Fairfield, California.

Photograph by KHOLOOD EID

| The New Mexico Trappers Association’s Tom Fisher, often called to remove problem beavers from people’s land, checks beaver traps in Rio Arriba County

Photograph by KHOLOOD EID