Alviso: 'Charismatic' burrowing owl protected by special habitat

A burrowing owl stands watch atop a post in the buffer lands near the San Jose-Santa Clara waste water treatment facility on April 19, 2014. (Courtesy of the City of San Jose Environmental Services Department)

SAN JOSE -- As a crow perches on a mound of earth, a pint-size chestnut-feathered owl emerges in front of it. The crow sits still, but the owl leaps forward, collides with the crow head-on and knocks it backward. The owl swoops away.

The confrontation in Alviso was captured on a motion-sensor camera that is documenting the rising population of burrowing owls at a South Bay preserve -- a trend that runs counter to an overall decline in the species.

And the photos and videos are providing a look at how the owls live.

"We get a look at the secret lives of burrowing owls," said Stephanie Ellis, executive director of the Santa Clara Valley Audubon Society (SCVAS).

Josh McCluskey, burrowing owls project manager for SCVAS, is among those who have been reviewing the footage of the western burrowing owl since the March installation of motion-sensor cameras that monitor a 180-acre owl habitat near the San Jose-Santa Clara Regional Wastewater Facility in Alviso.

Since 2012, a partnership between the Audubon Society and San Jose's Environmental Services Department, with the help of environmental studies experts and students from San Jose State and De Anza College, has created ideal conditions for the burrowing owl habitat.

That year very few owls lived on the Alviso site. Now there are 14 adults and 29 chicks.

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"This is the one place where their population can be built up to repopulate other areas, to be able to create habitats for them elsewhere," said Shani Kleinhaus, burrowing owl environmental advocate with the Audubon Society. "This is the one place where the population is increasing in the Bay Area."

The burrowing owls -- who are on average 9 inches tall and weigh a quarter of a pound -- are the only species of owl that lives in underground burrows. They are found in various places in California, such as the Bay Area and Imperial Valley, and also some locations in Mexico and Canada.

They are unusual among owls, according to Philip Higgins, biologist for the city of Mountain View, because they don't have ear tufts, are awake during the day as well as at night and do not hoot.

The Bay Area's burrowing owl population in the mid-1980s was estimated to be around 560 to 640 adult owls, three-fourths of them in the South Bay. By the 1990s the population had decreased by about 50 percent, and in 2009 there were only an estimated 70 adults left in the South Bay.

Two years ago, Higgins warned the burrowing owl -- listed by the state and U.S. Fish and Wildlife Service as a "species of conservation concern" but not yet endangered -- could become extinct by 2032.

A plan to create buffer zones to protect the owls was drawn up that same year by Higgins and Lynne Trulio, professor of environmental studies at San Jose State. They blamed the decline on habitat loss and lack of sufficient prey.

When the then-San Jose-Santa Clara Water Pollution Control Plant (now the San Jose-Santa Clara Regional Wastewater Facility) filed an environmental impact report in 2009 for future development of 2,600 acres of mostly barren land around the plant, the Audubon Society sought a dedicated space for the owls, and the city allocated 180 acres for the habitat.

Volunteers from the Audubon Society and city staff members began building artificial burrows and dirt mounds on the Alviso site for the owls, who make a mess in the burrows and then leave. The mounds attract squirrels, which create tunnels that owls can move into later.

Owls "can move to the next burrow, then the ground squirrels will move back in and the ground squirrels are very clean and they'll clean it all out and make it nice and neat," said McCluskey. "And then the owls will move right back in."

Volunteers also mowed the grass for the owls, which need grass to be shorter than 5 inches to scan the area for predators and prey, and put in perches to make scanning easier.

A year later, they saw more owls in the area, six adult pairs and 10 chicks.

"I like to call it a recipe and the recipe was really basic, like pound cake," said Ken Davies, the city's environmental services department compliance officer. "Put three things in there and you get this nice thing."

In addition to the Alviso site, owls are still present and protected at Shoreline Park in Mountain View, Moffett Field, and Mineta San Jose International Airport. But the Alviso habitat is considered ideal because it is restricted from the public and can be controlled.

"The only way to save them is to use existing sites," said Higgins. "If you lose one of (the sites), you're just increasing the chances of the bird becoming extinct in the area."

Installing motion-sensor cameras in March of this year made it easier to keep track of the owls, and gave observers insight into owls' lives.

Much of the city staff and Audubon Society's work involves the grind of separating photos of windswept brush from owl photos. But there have also been photos of young owls divebombing into each other to practice their hunting skills, and a video of an owl chasing a squirrel out of its burrow.

"They're a very charismatic bird," said Kleinhaus —... They come out during the day. ... They're real acrobats, they can hover, they can flip, they can do very amazing stuff."