Burrowing owl population making unlikely comeback

The owls are unique in that they are reliant on other animals, particularly ground squirrels and badgers, for shelter.

“It’s important that there is a healthy ground squirrel population for the owls to be able to survive because they're the only owl globally that has their nest in the ground versus a tree or cactus so they’re very unique, and they are dependent on other animals to dig the burrow,” said Edmund Sullivan, executive officer of the Santa Clara Valley Habitat Agency.

However, with increased development and efforts to minimize squirrel populations, the owls haven’t been able to access the habitats they need as reliably.

“Many times ground squirrels are viewed as pests species so they've been eradicated both by farmers and public agencies that are concerned about levies and infrastructure being undermined,” Sullivan said.

The owls are also dependent on short grass, and if the area’s invasive plants are not well-maintained, the birds are in even greater danger.

To boost the species’ population and long-term chances of survival, the Peninsula Open Space Trust — which works to protect land in the South Bay and Peninsula — started working with Santa Clara Valley Open Space Authority.

“We’ve created artificial burrow complexes to substitute for what nature would normally do,” Sullivan said.

Perhaps even more effective is the effort to raise some of the owls in captivity as a way to strengthen the population in certain areas, including near a wastewater facility, as about 70% of the birds would perish in the wild within the first so many months of their lives.

Statewide, the population is still declining, and the process of whether to list it as a threatened or endangered species is still ongoing. However, initial efforts seem to be working in the Bay Area. There were more than 100 adults counted in 2014 and, 11 years later, wildlife experts have been able to prevent the population from declining further, keeping it around the same number.

“These efforts show that when there's a regional collaborative effort between all levels of government, this is an example of government working — in this case to help a species,” Sullivan said. “Without funding, the birds would have disappeared.”