Video of a beaver living on Los Gatos Creek could be evidence of an ecological comeback for a keystone species in the Bay Area.
by Eric Johnson
Feb. 5, 2014—I watched a blurry, blown-out black-and-white video yesterday — it was the best thing I’ve seen in a while. Taken last Tuesday night, it depicts a medium-sized beaver at the foot of a pine tree along Los Gatos Creek over in Campbell. It’s the first beaver seen there in 150 years.
Steve Holmes, founder of Friends of Los Gatos Creek, captured the footage with a camera trap he’d set up for that purpose. He’s been tracking beaver there for months, ever since he and a colleague started finding beaver signs in various spots between Los Gatos and Campbell.
After Holmes posted the video on Facebook, another colleague, Greg Kerekes, suggested that the beaver might be a yearling related to a family of beavers found last summer on the Guadalupe River in the heart of downtown San Jose.
“I am finding evidence of Beaver in most of the watershed, from above Lexington [Reservoir] to Alviso,” he writes. “Old chewed trees I've found makes me suspect these beavers have been working the [Lower Guadalupe / Los Gatos Creek] system for at least two years.”
Why is this such good news to nature geeks? Because the famously industrious beaver is hard-wired to create a thriving ecosystem. Genetically programmed to gnaw down big old trees and dam up streams, beavers create wetland oasis. In the language of conservation biology, the beaver is a “keystone species” — a critter that modifies its territory so dramatically that it profoundly influences the surrounding environment.
Beavers, Wetlands and Wildlife, one of many sites set up to celebrate the buck-toothed wonders, list some of the benefits to having beavers in the neighborhood:
“Beavers reliably and economically maintain wetlands that sponge up floodwaters, alleviate droughts and floods (because their dams keep water on the land longer), lesson erosion, raise the water table and act as the ‘earth's kidneys’ to purify water. The latter occurs because several feet of silt collect upstream of older beaver dams, and toxics, such as pesticides, are broken down by microbes in the wetlands that beavers create. Thus, water downstream of dams is cleaner and requires less treatment for human use.”
In addition to doing all of this good work that benefits humans directly—referred to nowadays as “ecosystem services”—beavers also shape the community of flora and fauna in big ways. Big fish, which around here could include steelhead trout and Chinook salmon, move into the ponds. They’re followed by predator birds—perhaps great blue herons and osprey—while smaller birds nest in the dense coppices of cottonwood, aspen and other shoreline trees. Bigger mammals, from deer and coyote to mountain lions, also love beaver ponds.
Before the population was practically eliminated, there was no land animal that had a more profound effect on the environment than the North American beaver.
When we think of pristine, untrammeled nature, we might picture herds of buffalo, soaring eagles, leaping salmon. We should think beavers.
The discovery of beavers in Los Gatos Creek and the Guadalupe River is part of a bigger story about the comeback of surface waterways in the San Francisco Bay Area. A family of beavers found in Martinez in 2006 made national news—it’s not impossible that the South Bay clan is related.
And Friends of Los Gatos Creek, which has been conducting cleanups every other month since it was founded last summer, has documented Chinook salmon breeding and nesting.
I’ve reached out to some local wildlife biologists to get the history about beavers in Santa Cruz County, and see if there’s any news. Will let you know what I find.