Beavers are again: Pictures show Los Altos resident’s concept that rodents reside in county | Group

Courtesy of Rick Lanman

A Los Altos resident has solved the mystery of the missing beaver population.

A Beavers were sighted in Palo Alto last April for the first time in 160 years, captured by Bill Litaken’s black-and-white trail cameras at Matadero Creek. Then, in September, another of Litaken’s cameras caught a beaver there – this time in color.

The photos confirmed what Los Altos resident Dr. Rick Lanman has believed for years – that beavers are native to Santa Clara County. While saying that many naturalists assumed the aquatic rodents never lived here, Lanman built a case that paralleled it. After years of research, he presented a scientific study this fall showing that there were beavers in the county as early as the 19th century.

A retired physician and biotech executive with a hobby in historical ecology, Lanman lives in a house near Adobe Creek. His curiosity as to whether steelhead trout had ever lived in the stream led him to suspect that beavers also used the waterway in the past. He said the home’s previous owner told him he liked to go fly-fishing in the creek up until the 1950s.

“That got me curious,” Lanman said. “I asked the water district if there was any evidence of trout and they said, ‘No, there was never any trout in the creek.’ Well, I hiked up the creek… and under El Camino (Real) there’s a 10 or 15 foot fish ladder. Why would they build a fish ladder when there are never any trout in the creek?”

Lanman ventured into the Hidden Villa Conservation Area in Los Altos Hills, where people who have lived in the area for many years told him there was once a trout in the creek. Lanman concluded that the fish were no longer there because a rectangular concrete canal had been built.

“A concrete channel probably eliminated the steelhead trout’s ability to surface,” he said. “When you turn a stream into a rectangular or trapezoidal canal, the bottom is perfectly flat. It’s raining, but you get an inch of water flowing at 30 miles per hour. No fish can swim against it.”

That solved the mystery of the missing trout. However, there was still the problem that the stream ran dry. Lanman suspected the reason was beaver ponds.

“Beaver ponds raise the water table,” he said. “They are like seepage basins. Water seeps into the ground and the groundwater level rises. In the dry season, the high groundwater level feeds the stream and keeps it flowing.”

However, when Lanman went to the California Department of Fish and Wildlife (CDFW) to confirm his hypothesis, he said they told him there had never been beavers in California. Furthermore, in the 1937 novel Fur-bearing Mammals of California by Joseph Grinnell, the first director of the Museum of Vertebrate Zoology at UC Berkeley, the author writes that beavers only existed in the Central Valley of California and none in coastal watersheds like that bay area.

Unconvinced, Lanman began looking elsewhere.

He first searched the California Academy of Sciences, where he found physical evidence of steelhead trout, using the older names for the location and specimen.

“I looked for references to beaver and steelhead and thought there wasn’t any until I realized Adobe Creek used to be called San Antonio Creek,” Lanman said. “It also struck me that steelhead trout has a different scientific name today than it did before 1900. When I searched the terms ‘San Antonio Creek’ and the old Latin name for steelhead trout, I found three specimens collected from the California Academy of Sciences 1890s from our creek just behind my house.”

Although Lanman had evidence of trout, he still required evidence of beavers. Because many museum specimens in California were destroyed by the 1906 San Francisco earthquake and fires, Lanman looked out of state at the Smithsonian Institution.

“I found a beaver skull in the Smithsonian that was collected in Santa Clara County at Quito Creek, which is the old name for Saratoga Creek,” he said. “This was the first physical evidence that beavers actually used a coastal watershed, namely a tributary of Santa Clara County or San Francisco Bay.”

Through further investigation, Lanman discovered a beaver fang at an archeological dig in Del Norte County, more beaver remains at an archeological site in Alameda County, and finally a beaver skull in the Museum of Vertebrate Zoology at UC Berkeley.

“Another physician, naturalist, who was with the Los Angeles County Museum of Natural History had collected the skull after 1900 and given it to Berkeley, but Grinnell ignored it in his 1937 book,” Lanman said. “He just couldn’t believe it. His thoughts were focused on what we call ‘shifting baseline syndrome,’ that is, when biologists believe that the animals that live here, and their abundance and distribution, are historically still what they were when the biologist was born.”

Through communication with CDFW biologists, Lanman learned that the next beaver sighting was in 1980 in upper Los Gatos Creek above Lexington Reservoir after some beavers clogged a channel in the Central Valley. The beavers didn’t stop there; they continued to move down.

“In the 1990s, there were reports of beavers below the dam, in lower Los Gatos Creek, and in Los Gatos and Saratoga,” Lanman said. “Los Gatos Creek empties into the Guadalupe River, which empties into the bay. In the 2010s there were reports of beavers building dams in downtown San Jose, and now there are beaver dams in a creek on the east side of San Jose.”

Then there were beaver tracks at the end of San Antonio Road, north of Shoreline, and beaver in ponds at the Sunnyvale Water Pollution Control Plant. The beaver sighted in Palo Alto is the most recent sighting, according to Lanman.

“They’re gradually coming up the bay, starting in Los Gatos Creek above Lexington Reservoir,” he said. “The same thing is happening in the North Bay. Beavers move. They moved from Contra Costa County to Napa County to Sonoma County and now I think they’re almost there. … They use the bay as a highway to gradually expand their territory.”

However, it appears that the beavers cannot cross Adobe Creek into the Los Altos area because of the cement concrete flood control channels leading from El Camino to the bay.

“No beaver, no fox, no bobcat, no animal can walk up the concrete,” Lanman said. “They are totally exposed to predators: hawks, hawks, owls, coyotes. Therefore, beavers are unlikely to use these means to get through our cities to the highlands.”

The return of beavers to the Bay Area brings both positive and negative changes, Lanman noted. He cited three positive aspects: beavers are key species that support many other species, they perpetuate streams by raising water tables, and beaver ponds can act as shelters from wildfires. The Cons: Beavers cut down trees and could potentially cause flooding. However, both of these problems can be mitigated, Lanman explained.

“There is a very simple solution. You just mix sand into gray latex paint and paint the bottom of the log and they won’t gnaw it; You can’t stand the feeling of sand on the trunk,” he said. “There are also ways to manage (floods). They simply put a pipe through the dam at the desired height and a wire cage around the upstream part where the beaver pond is so they can’t clog it with sticks. It is called a “beaver scammer”. These things are well established on the east coast.”

Lanman hopes that finding beavers in the Bay Area will help with recovery and future scientific research in the area.

“I hope all of this serves as a guide to the restoration and understanding of what was actually here,” he said. “So much of this is misunderstood because we basically took the state from Mexico in the mid-19th century and no museums were built. Then when we finally build museums, it was the late 19th century and they were destroyed in 1906. And then we have shifting baseline syndrome, where everyone has these wrong assumptions. Do you know that there used to be moose here? Can you imagine?”