The swallows may not be flocking back to Capistrano these days, but the beavers have returned to San Jose.
Even when they're not receiving guests, curled wood shavings and girdled willow trees give the critters away. It started when a lone beaver was spotted in the Guadalupe River, just across the street from HP Pavilion in downtown San Jose.
Thrilled, the Guadalupe River Park Conservancy set up a trail camera to monitor its activity.
Then another beaver appeared.
“I jumped up out of my chair and high-fived my wife and hugged her when I saw the second beaver,” said Greg Kerekes of the conservancy, after going through the camera footage.
Soon, he discovered that three beavers, a pregnant mother and her two yearlings, were keeping house at the confluence of the Guadalupe River and Los Gatos Creek. A family indicates they will likely settle, said conservancy executive director Leslee Hamilton.
Environmental educators hope the beavers will stay because they benefit wildlife and can help teach children about watersheds.
“Eyes get really wide when children hear about salmon in the river,” Hamilton said. “The beavers will enrich our program and show kids what an ecosystem is.”
The Santa Clara Valley Water District has decided that the beavers do not pose a threat to flood protection efforts. Located near a water intake, Hamilton says the beavers could not have picked a better spot. If water rises to a certain point, it pours into an underground concrete channel bypass that leads to a flood control plain.
In 2007, a family of beavers also colonized Alhambra Creek in downtown Martinez.
“You could sit at Starbucks, drink your morning coffee and watch kits (young beavers) play,” said Heidi Perryman, president of Worth a Dam, a beaver advocacy organization.
Since the beavers have settled in Martinez, the ecosystem has flourished, seeing at least 13 new species.
“The next year, the river otter returned, no doubt to hunt the now plentiful fish in the beaver ponds. Then the year after, the mink returned,” said Rick Lanman of the Institute of Historical Ecology in Los Altos. “All manner of birds and fish have returned, and we don't even know how many species of dragonflies and damselflies.”
Beaver supporters praise the benefits that beavers bestow on the environment. The “ecosystem engineers” are a keystone species, and they raise water tables, create wetlands, clean water, slow water down and restore topsoil.
Lanman called beaver-created ponds “factories” for producing insects and fish, and “cafeterias” for birds and salmonids, such as trout and salmon.
Federally endangered species also benefit, such as the California red-legged frog and the southwest willow flycatcher. Beavers will cut down some trees and widen the amount of riverbank that gets watered, resulting in a net increase of trees, according to Lanman.
Armed with two industrial-grade incisors, beavers are often considered a nuisance. They cause problems with agriculture, damming irrigation canals and chewing trees. They also wreak havoc in urban areas, gnawing landscaping and flooding fields.
Beavers, North America’s largest rodents, are native to the Bay Area, but their numbers dwindled because of fur trading. In 1997, they were reintroduced to the Lexington Reservoir in Los Gatos, and the Guadalupe beavers arrived by swimming down Los Gatos Creek.
“A lost species has found its way back,” Kerekes said.
The beavers are starting to spread in the South Bay, a sign that the ecosystem may be able to support larger mammals again and that restoration efforts have been successful.
Norma Camacho, the water district’s chief operating officer for watersheds, said she is thrilled that efforts to improve the Guadalupe ecosystem are working.
Last year, a beaver was spotted in the Guadalupe River near Hedding Street in San Jose and another at the Sunnyvale Water Pollution Control Plant. In 2008, beaver tracks were also spotted in Charleston Slough near the Palo Alto-Mountain View border.
“They have been cruising the South Bay for awhile,” Lanman said. “The conversion of the South Bay salt ponds back to tidal marsh may be providing the beaver with a means to access the South Bay rivers. Beaver can cross salt water easily and even live in it if it's brackish.”
Perryman said people could see the beavers as a good sign for the river and its good fortune, adding that beavers revitalize ecosystems for free, unlike cities.
“A small investment in restoration continues to yield dividends,” Lanman said.