Pictured: A mother beaver with two kits in Sugar Creek, Scott Valley, California. California Department of Fish and Wildlife, photo by Charnna Gilmore. 

by Kimberly Rivers

Maybe Smokey the Bear should have been a beaver. 

People may have coined the phrase “Slow It, Spread It, Sink It,” but beavers, with design consulting from Mother Nature, are the original developers of the concept and engineers of how it works. Scientists now digging into the skills of these large rodents are seeing a way to help communities further harden their built environments from wildfire. 

Communities across California, as well as many Western states, are searching for ways to fire harden urban interface zones and buffer areas. One emerging concept — that seems new but is actually rooted in millions of years of habitat and wildlife evolution — is that encouraging the North American beaver to return or to be reintroduced to historic habitat areas may have a positive impact in terms of fire resistance.  

A lodge built by a North American Beaver.

All of Ventura County is part of the historical habitat of beavers. Tsǝ’ pǝk is the Chumash word for beaver, and there are at least two places in Ventura County named after the animal. Beaver Campground and Beaver Camp are approximately northwest of the Ventura River where it nears the Pacific Ocean. 

“I’d be pretty shocked if there was actually zero in Ventura County, but the population is very small if it is here,” said Dr. Emily Fairfax Ph.D., assistant professor of Environmental Science and Resource Management at California State University Channel Islands (CSUCI). She holds a double-major bachelor’s degree in chemistry and physics, and a PhD in geological sciences from University of Colorado, Boulder. Her research combines high-tech remote sensing methods along with tried-and-true ground truthing work in the field. 

Dr. Emily Fairfax groundtruthing beavers. Photo submitted.

There are confirmed beavers populations today in Santa Barbara, San Luis Opispo and Kern counties. Fairfax thinks it’s likely that at least a few make Ventura County their home as well. 

“They are probably here somewhere; the county is half forest land by area and I’ve absolutely not explored every single stream.” 

The native beaver population was hunted to extinction and then reintroduced in the 1940s to the area. “They dropped [approximately] 40 in the Sespe Wilderness. I’ve talked to people in Ventura County, in Ojai that say, ‘Yah, there are beavers’” in the Sespe, but that was up until about 2000. “They stopped seeing them. I’ve gone looking, but haven’t seen any live beavers.” She did, however, find “old beaver-chewed sticks” in Ventura County.

Nature’s engineers

Fairfax has published two studies so far regarding the busy beaver with another in the works. 

“I always liked wetlands even as a kid growing up,” she said. She remembers elementary school field trips to local wetlands, and she was somewhat aware of beavers, “but hadn’t really thought about them in a serious way.” She noticed elaborate beaver complexes in the boundary waters of Minnesota when she was leading kayak trips. She had a mild interest at that point but, “I didn’t know there were jobs” related to beavers. 

A pond behind a beaver dam in Atascadero. Photo by Dr. Emily Fairfax, used with permission.

She was working as an engineer after college and found that she was inexplicably drawn to the habitat of this watershed engineer. 

“I kept trying to go to wetlands, to get outdoors, go fishing, and I couldn’t really shake that I wasn’t on the right job path.” 

The epiphany came when she was watching a Public Broadcasting Station (PBS) documentary called Leave It to Beavers. The show aired in 2014 and explained some of what was known about beavers at the time.  

Fairfax saw beaver complexes in the desert. “It was bright green, the areas around the beaver complexes were dry and in a horrible degraded state, except for where there were beaver dams. I was hooked.” 

On the show they interviewed geomorphologists, who study how the earth is shaped and changes due to the elements. “They said there is so much we still don’t know about beavers, that it’s an open area of research. Is it really?” she wondered. “And it was. I quit my job to study beavers and haven’t looked back.” 

The first study she published on beavers was focused on the beaver complexes highlighted in that PBS documentary and showed how beavers returning to a watershed in Nevada helped the local ecosystem around the creeks, called a riparian habitat, during a drought. 

A North American Beaver.

“In Nevada, the Susie and Maggie Creeks, it’s a famous restoration story now. They were very, very degraded. The ranchers teamed up with the land managers. They weren’t thinking about beavers. They were just managing grazing a little better, trying to make the riparian [area] better. Then the beavers came back.” The restoration went faster with the beavers’ help and when a major drought hit, “The only places with any greenery or any water was around the beaver complexes. It was actually greener than everything else. It was pretty cool.” 

Beaver complexes are made up of dams, ponds and dens called “lodges” as well as streams and canals the beavers dig out and use as a roadway.

“From the ponds they dig out into the landscape,” building a kind of beaver freeway system of “canals used to swim around in to get to trees, building materials . . . A big web of water on the landscape.” 

Smokey the Beaver

Fairfax explained that beavers are pretty clumsy on land and vulnerable to predators, but in the water they are fairly safe. Their need for protection from predators has evolved over millions of years into the behavior of building major networks of water management infrastructure parts that effectively slow the flow of water, then spread the water over a wider area, causing the riparian habitat to widen around the waterway — not just above the ground, but under the surface as well. 

Image from “Smokey the Beaver” study.

“Smokey the Beaver came after that [initial research]. If beaver activity can help keep plants lush and green in a drought . . . the next logical step is that greener vegetation is harder to burn, and it was,” said Fairfax explaining the impetus for her recent research work titled “Smokey the Beaver.” The published, peer-reviewed paper demonstrates how beaver complexes create an area protected from fire for not only the beaver, but other wildfire and vegetation. (1) The beaver complex areas can be seen from satellites. 

Her Smokey the Beaver study found that “overall, riparian zones with beaver activity were three times less affected by wildfires compared to riparian zones without beaver activity.” 

The beaver complexes were green refuges among the dry, charred surrounding landscape. Fairfax’s research found that this is because the beaver is an expert at the concept of “Slow It, Spread It, Sink It,” a concept some humans in flood management and drought response are working to incorporate into stormwater runoff management. Instead of designing gutters, washes, 

downspouts and drains to push water out and away as fast as possible, the water is slowed down, spread out and allowed to sink.  

Fairfax’s research continues. “I’m currently looking at fire refugia that beavers are creating.” 

She described fire refugia as “a patch within a fire perimeter that doesn’t burn, or it burns with low intensity, a pocket of preserved habitat . . . I’m looking at mega fires in Colorado, they’ve been really huge and explosive. There are tons of beavers in the fire perimeters. Preliminary data is showing that these beavers had no issue even during these extreme fire events.” The areas that the beavers are working in “are better equipped to handle that disturbance.” 

Busy builders

“They eat plants; just plants. It’s a common myth that they eat fish. Beavers do not eat fish. Their preferred food is the sugary layer between the bark and the wood…the cambium layer.” Generally they like willow, birch and aspen. “They will scrape the bark to eat and use the wood for working with. If it’s a small twig, they’ll eat the whole thing.” They also eat cattails, pond weed and any other leafy aquatic or semi-aquatic plant. 

Some may worry about beavers doing damage to trees and taking too many down for their complexes. Fairfax pointed out that “the trees that they prefer to eat are trees that have been living in the same habitat [with the beavers] for millions of years.”  Willows and cottonwoods are their preferred tree. When a beaver takes a branch of a willow, “almost immediately 10 new shoots” will grow. A certain location in fall might look like a beaver has chewed a lot of wood, but the same place in spring will reveal abundant fresh growth. “In spring you can’t see what the beaver has chewed.”  

Beavers “will use whatever they can get their paws on when they’re building. I’ve seen them use [orange roadway] cones and styrofoam coolers.” 

While beavers are apt to use any wood lying around on the ground, potentially clearing out dry fire fuel, Fairfax said that in the areas around where beavers live researchers don’t see a lot of dry wood. “They keep the area around their homes so wet . . . wood on the ground just doesn’t dry out, and doesn’t become fire fuel.” It’s likely to be damp, and just rot. 

Beavers are a bit opportunistic and generally only choose branches or smaller trees to chew and use for construction. If there is a huge downed tree, they’re unlikely to use it; dead trees don’t have the cambium layer. They are capable, nevertheless, of chewing through large trees, and may wait for them to fall and use any that are the right size. 

Life in the lodge

Fairfax explained that beavers mate for life and are monogamous. They give birth once a year, every year. Their litters, called kits, are generally one to three babies. “The maximum I’ve heard of is six.” The babies live with mom and dad in the lodge for two to three years. “Mom and dad kick out the yearlings [at 2 or 3 years old] to make room for the next batch of kids. A full family unit is made up of the parents, two babies, two to three yearlings. Five to seven beavers is pretty normal.” 

Adult beavers range in size from 40 to 100 pounds. Mountain lions, wolves and bears are their main predators. 

“They have more predators when they are babies,” Fairfax continued. “At that point bobcats, coyotes, hawks, anything that can grab a small rodent.” Thus, parent beavers strive to keep the babies in the lodge until large enough to be safe from these common threats. 

Fairfax discounted the idea that beaver populations would explode if reintroduced. “That is not realistic.” They only have a couple of offspring each year and it takes a long time for beavers to establish a large population. 

Reckoning with re-beavering

Is it possible to reintroduce beavers?

“It is realistic. It’s something that people are already doing in other states like Colorado,” Fairfax said. “It’s common in Washington, you can do it in Oregon.” 

But not in California currently. 

“It’s illegal here. You can’t move a live beaver for that purpose.” 

The California Fish and Wildlife code prohibits the relocation of a live beaver. Ironically, the law allows people to trap a beaver only with the intention to kill it. For some homeowners, this becomes the only option available to them when a beaver finds itself in a place where their engineering skills cause more problems for people than benefits. 

For example, beavers can set up shop near a freeway and build a dam that leads to highway flooding. In other cases beavers can start chewing agricultural areas like orchards. But Fairfax said there are alternatives and, thankfully, more people are informed about those options. Trees can be wrapped and special fencing is designed to keep out beavers. She said most of the people she’s spoken with who have received the lethal trapping permits for beavers express dismay at having to go that route: They’d much rather the beaver be relocated to a suitable habitat. 

Trees in an orchard are wrapped with hard plastic to prevent chewing from beavers.

“If you’re one of those beavers,” living in the wrong place, “a beaver on death row, the options are limited. You can only lethally trap them. I’d love to see this policy change.” According to Fairfax, 1,000 beavers were lethally trapped in California last year. Many of them were trapped in the Sacramento area, the Sierra Nevadas and the Central Valley. Reasons given for the application of permits are frequently that the beavers are chewing someone’s favorite trees on their property, or taking agricultural products, or that the beaver is causing flooding. 

“Of those, if they were relocated and if only half survived, that is not only a better outlook for those animals, the parts of California where the beaver would be would not be conflicting with people.” She said that while other counties on the Central Coast are seeing a re-beavering through beavers naturally moving back, much of California’s natural historical habitat for beavers is “not fully re-beavered. Relocation should be available in this state.” 

There are a number of options for dealing with undesirable beavers. Trees can be painted with paint laced with sand. “The beavers don’t like how it feels on their teeth,” Fairfax explained. If a beaver is managing a pond and causing floods, there is a mechanism for managing the pond depth rather than the beaver. This allows the beaver to stay in place where the other water spreading benefits are desired. 

Fairfax also said there are steps humans can take to improve local riparian habitats, such as fake beaver dams called BDAs or Beaver Dam Analogs, which are considered low-tech, process-based restoration, designed to “nudge the river back to a state where it can sustain itself.” In her opinion, BDAs are perfect for Ventura County, particularly in the Ventura River Watershed. 

BDAs and similar steps would aim to mimic what a resident beaver would do and also create an area that could lure a beaver browsing for a new abode to set up shop and start putting her engineering skills to work, benefiting the watershed and supporting local fire prevention efforts. 

Beavers among us?

Fairfax has given a presentation to participants in the California Certified Naturalist program about how to identify whether beavers are in the area. 

“Look for those sticks that they chew. No other animal chews sticks that way. Find a dam; no other animals build dams, except for people.”

She asks the public to make sure to report any findings and encourages the use of the online program iNaturalist, which includes both a smartphone app and website. This allows citizen scientists all over the world to document sightings of both common and rare flora and fauna, documenting biodiversity and changes to habitats. She regularly checks for beaver sightings on iNaturalist in Ventura County and other places where they are rare or haven’t been seen recently, but where she’d expect them to be seen. 

“They are in nearby counties. If nearby, they can move in one direction and it’s possible they’ll start coming to this county.”      

  1. Smokey the Beaver: Beaver–Dammed Riparian Corridors Stay Green During Wildfire Throughout the Western USA, Emily Fairfax, Andrew Whittle, Ecological Applications, Vol. 30, Issue 8, Dec. 2020. https://esajournals.onlinelibrary.wiley.com/doi/10.1002/eap.2225

  2. https://www.pbs.org/wnet/nature/leave-it-to-beavers-production-credits/8860/