While at its peak, Santa Clara County supported hundreds of adult owl pairs, the Santa Clara Valley Habitat Agency recorded just 52 to 53 adults in its 2019 annual report. The Valley Habitat Agency was formed in 2013 by local governing bodies to protect endangered and threatened species from the impacts of development.
Sunnyvale and Fremont have all but lost their owl populations, but Mountain View remains one of the few places in the county that the ground-nesting birds still call home.
In June, the Valley Habitat Agency launched its latest owl conservation effort, a pilot program to remove the smallest and weakest owlets from several nests and raise them in captivity. The Peninsula Humane Society is rearing the 14 chicks — 10 removed from nests and four orphans — in its Burlingame nursery over the next nine months. Two of the chicks came from Mountain View's Shoreline Park.
The birds' temporary home comes equipped with artificial grass, burrows, rocks and secure walls and overhead netting to protect them from predators. According to PHS spokesperson Buffy Tarbox, the owls have extremely limited interaction with humans and other animals to keep them wild and help them assimilate back into their natural habitats.
In the spring, scientists will release the birds into artificial burrows in pairs to encourage breeding, according to Edmund Sullivan, director of the Valley Habitat Agency. Shoreline Park, the Don Edwards Wildlife Preserve in Fremont and the San Jose-Santa Clara Regional Wastewater Facility are likely release sites, he said.
Nearly 70% of burrowing owl chicks die in their first year in the wild, often from predators, harsh conditions or lack of food. Tarbox said the program will allow mothers to concentrate on a smaller nest of young, while ensuring that the handful of captive owls can grow to be strong and healthy adults.
"It's a lot of human intervention in recovering species, but it does increase the chances that (they) will survive," Sullivan said.
A two-year supplemental feeding program that concluded last year produced all-time high birth rates among nests, with one pair at Moffett Airfield delivering nine chicks. With a high-protein meal of dead mice, healthier adult owls expended less energy on foraging, breeding more chicks and dramatically reducing the likelihood of young owls fighting over food.
A "longshot" idea proposed by the Valley Habitat Agency would involve encouraging migratory burrowing owls that winter in the Bay Area to live here year-round, Sullivan said.
Overwintering owls from Canada and the northwest far outnumber year-round breeding owls in California. While the notion of changing a bird's instinctive migratory behavior is largely experimental, "if we can encourage some of the birds from North America to stay, it'll increase the robustness of our local population, from a gene pool standpoint and a sheer numbers standpoint," Sullivan said.
To Shani Kleinhaus, environmental advocate with the Audubon Society, captive breeding may be what's next for a species where mating in the wild poses a significant challenge if no nearby nests exist.
"We're at a place where the population is too small," Kleinhaus said.
The steep decline of burrowing owls could have unknown consequences on the area's ecosystem. The owls control rodents and insects and serve as prey for larger birds and mammals like coyotes, cats and raccoons.
For environmental organizations like the Valley Habitat Agency, the protection of wildlife is paramount from an ethical standpoint.
"Not allowing any species to go extinct ... is a stewardship responsibility of humans," Sullivan said.
Kleinhaus said she remains hopeful that Mountain View can recover its burrowing owl population and called the city a leader in tackling the problem, from its hiring of full-time biologist Phil Higgins to its adoption of the Burrowing Owl Preservation Plan in 2012 and preservation of the Shoreline Regional Wildlife Area.
Sullivan said he feels encouraged by the Bay Area's preservation of rural areas and a heightened focus on denser and transit-oriented development. He pointed to a San Jose infrastructure bond passed in November that included $50 million for protection of Coyote Valley.
NASA has also committed to maintaining the Moffett Airfield as burrowing owl habitat, and Google has contributed to the agency's efforts by installing fencing, constructing state-of-the-art artificial burrows and monitoring the preserves year-round, according to Google.
"There's a lot of momentum now, and we have an array of partners to help us succeed," Sullivan said. "The time is now. We have to try."
This story contains 803 words.
Stories older than 90 days are available only to subscribing members. Please help sustain quality local journalism by becoming a subscribing member today.
If you are already a subscriber, please log in so you can continue to enjoy unlimited access to stories and archives. Subscriptions start at $5 per month and may be cancelled at any time.