One among many inhabitants struggling to cope in a changing landscape, Mountain View's fragile burrowing owl population appears to be slumping, raising concern among environmentalists that the species could make an exit from Shoreline Park.
The predatory birds, which are listed as a California species of special concern, inhabit the 750 acres of open space just beyond the North Bayshore tech corridor that's marked for rapid expansion. Tech companies looking to grow, including Google, are required to follow a set of city guidelines meant to protect the owl habitat. But even with those safeguards, bird advocates fear that the presence of thousands more workers and residents in the area will end up harming the bird population.
Shoreline Park's burrowing owl population has hit a new low, said Shani Kleinhaus, an ecologist with the Santa Clara Valley Audubon Society. She points to the Mountain View's latest report, which showed only one successful breeding pair of nesting owls, the smallest number in the last 18 years.
"That's really at the verge of extinction," Kleinhaus said. "We're seeing a lot of disturbance and we think that might be a reason for the decline."
While the owls did have four chicks, there were problems. The breeding pair was a mother and son, a bad sign for the population's future.
There are many factors that could explain the low numbers. The owls are ground-nesting, living in holes hollowed out by squirrels. That can leave them vulnerable to a long list of predators, including foxes, skunks and raccoons. Feral cats are considered the worst of the lot, preying on owls as well as the small birds and rodents that make up the owls' main food supply. In fact, a released cat last year ended up mauling one prolific male owl, Kleinhaus said.
Humans can also be a big nuisance for the owls. City parks staffers have installed signs and fencing to cordon off sensitive areas, but hikers sometimes go trailblazing. Shoreline Park prohibits dogs except in an off-leash zone near the entrance, yet some people still untether their canines in other parts of the park.
By the city's count, Shoreline Park has a total of five burrowing owls, although other migratory owls come from the north to spend the colder months there, said Recreation Manager John Marchant. City workers have tried their best to create a suitable habitat for the owls by building artificial owl holes and mowing down the nearby grasses to prevent predators from catching the birds off-guard. In an effort to encourage more natural owl habitat, parks staff sometimes set up squirrel traps around the nearby golf course. The squirrels are later released in areas more suitable for owls, with the idea that they will dig new holes that owls can use.
"We're doing everything in our power to make sure we're not disturbing the owls," Marchant said. "We're putting a lot of time, effort and resources into protecting these species in hopes it'll expand the population within the park."
The burrowing owl is native to a wide area stretching from northern Mexico up to western Canada, yet the population in the South Bay has been declining for decades. The local owl population numbered in the hundreds in the 1990s, but in recent years that number has dropped to around 70 birds.
Why did the population plummet so dramatically? In short, Kleinhaus points to the long history of office development on the bay landfills from Milpitas to Mountain View. She admits she is in a conflicted position in discussing this topic she works as a consultant for Google, advising the company on how to minimize its impacts on the species.
Some public speakers criticized Google's newest planned expansion of its Charleston East campus for setting a dangerous precedent since the project's northwest corner would encroach on the buffer zone of the owl habitat. Yet city officials and Kleinhaus both say the move won't impact the owls since the construction area will be separated from the bird habitat by the four-lane Amphitheatre Parkway.
Overall, Kleinhaus described the push to dramatically expand offices and residences in North Bayshore as "a cause for concern," potentially bringing tens of thousands more humans near the struggling owl population. But she insisted that risks could be counterbalanced.
"Google is looking to mitigate and build habitat for the owl to create places where the population can increase," she said. "If the conditions are right, we think the owls will come back."