“…beavers are landscape miracle drugs. Need to enhance salmon runs? There’s a beaver for that. Want to recharge groundwater? Add a beaver. Hoping to adapt to climate change? Take two beavers and check back in a year.” Kent Woodruff in “The Beaver Whisperer,” High Country News

two beaver kits
Source: Cheryl Reynolds, 2013 (Worth a Dam, www.martinezbeavers.org)

At one time, there were beavers living in west coast streams from Canada to Mexico. By the 1830’s a mania for top hats and fur coats had devastated their numbers, along with those of fur seals and sea otters. Beaver are still on both U.S. Wildlife Services and California Fish & Wildlife’s list of ‘vermin’ because they can be destructive and cause flooding. As designated vermin, they generally can’t be moved to another site, so the main option to get rid of them has been extermination.

In 1833 General Vallejo observed that there were huge numbers of beavers living in the Laguna de Santa Rosa. Many historical records also confirm beaver population in Sonoma County, although it is not officially considered beaver habitat by the state. A 2013 study published by California Fish and Game’s journal collected the historical evidence and showed that most of California was and is potential beaver habitat. New understanding of the benefits that beaver can bring to a landscape, particularly to salmon habitat, has a number of dedicated beaver lovers in the North Bay working to bring them back. In Sonoma County, the Occidental Arts & Ecology Center (OAEC) has just published an extensive report called Beaver in California: Creating a Culture of Stewardship.

The life of a beaver

The American beaver, Castor canadensis, is a very large rodent that lives in the riparian zone of streams. Beavers are herbivorous, using their large front teeth to chew the inner bank of young trees and to eat grasses, bulbs and other plant material. Beavers make mud and log dams on streams in order to create a pond to keep themselves safe. The beaver family either digs a burrow in a bank, or builds a ‘lodge’ from sticks and mud in the middle of the pond that has an underwater entryway and an above-water inner chamber. The lodge keeps the family secure from predators like coyotes, mountain lions and even hawks.

Video: “2 kits and parent,” Napa Beavers, June 17, 2014.

Environmental improvements to the landscape

By felling trees and making ponds, beavers create diverse micro-habitats, adding wetlands and deep pools. According to the OAEC report, fish, insects, birds and amphibians and river otters proliferate in beaver-influenced landscapes. Beaver dams slow down streams, reduce erosion, and allow water to sink into the ground. The ponds they make are deep, cool places where young fish, like coho salmon smolt, can survive through the summer.

Beaver increase diversity in plant life as well. Shallow parts of the beaver pond become wetlands and eventually meadows where unusual plant species can flourish. Beaver ponds and marshes help to filter out sediment and pollutants, making the downstream water cleaner. Wetlands support greater plant growth and also wet decomposition of plants which removes 5 to 40% of nitrogen pollution from stream water.

Beaver activity even sequesters carbon. Recent research shows that meadows and wetlands created by beavers capture more carbon than the grassland or forest that they replaced. One estimate by geologist Ellen Wohl is that a beaver meadow contains 10 to 30 times the carbon of a dry grassland, depending on its size and age.

Compare the natural improvements that beaver make to a stream to the restoration currently taking place on Dry Creek (tributary of the Russian River) in order to make the creek more hospitable to steelhead and coho salmon. This restoration project, forecast to cost about $50 million, involves slowing down the stream with woody debris and creating ponds and side channels. Wouldn’t it be cheaper to get beavers to do the job? In the Fish & Game article, one scientific study showed that beaver ponds harbored 80 times more coho smelt than a pool made artificially with large woody debris, while another showed that three times the number of juvenile Chinook salmon lived in areas where beaver dams were present in the Skagit River wetlands. Since salmon and beaver evolved to live together, migrating coho have no trouble jumping over beaver dams on their way upstream to spawn.

Learning to live with the urban beaver

Beaver seem to be slowly moving back to the North Bay. A nonprofit in Martinez called Worth a Dam just held its 9th annual Beaver Festival, celebrating the more or less continuous occupation of a pond on Alhambra Creek since 2007. When beaver first moved into Alhambra Creek, in downtown Martinez, the city made plans to have them trapped and killed. A group of residents persuaded the city council to try an intervention that would keep the pond from flooding and it was successful. Beaver also appeared in downtown Napa in 2014 and are still there.

beaver dam on Sonoma Creek
Source: Cheryl Reynolds, 2009, beaver dam on Sonoma Creek. (Wikipedia)

In Sonoma County there is only one verified beaver pond, on Sonoma Creek in Maxwell Farms Regional Park just outside the city of Sonoma. This is the second recent attempt by beavers to repopulate Sonoma Creek. According to an article in the Bohemian, a beaver family moved up Sonoma Creek to Glen Ellen in the 1990s, but was caught eating grapevines and exterminated. Left to themselves though, they will slowly re-populate our streams. Young beavers naturally disperse to find their own territory as adults and move from one watershed to another, either overland or by water.

The most common complaints about beavers have to do with flooding, tree-killing, or chewing through infrastructure, but these problems have solutions. Both the OAEC report and CDFW recommend low-tech fixes for living in harmony with beavers, such as protecting special trees with beaver-proof paint or tree guards, or overflow pipes for beaver ponds to keep them at a certain level. Also necessary is a change of human attitude, regarding beaver as environmental friends rather than enemies.









Why we need beavers
Tagged on: