Over the last few decades, the population of breeding western burrowing owls has declined in Santa Clara County. Burrowing owls have been documented spending the winter in our parks and open space preserves, but these winter migrants do not stay into the summer to breed. Local researchers are testing a new conservation strategy – building burrows for these owls that might attract them to stay year-round.
As part of the 2012 Santa Clara County Habitat Conservation Plan, local agencies are committed to protecting habitat and implementing other strategies to attract and retain a healthy population of breeding burrowing owls. Protection and restoration of habitat for native species is one of the Authority’s top conservation priorities. One strategy is to entice wintering owls to stay and breed by creating artificial burrows, custom-built to include all the features that the owls are known to be drawn to in the breeding season. This artificial burrow strategy has never been tried with wintering western burrowing owls, though some similar studies have shown promise in attracting other species of birds.
This past September, researchers worked with the Open Space Authority to create burrows and manage habitat at Sierra Vista Open Space Preserve. The research team was led by Dr. Lynne Trulio, Professor of Environmental Studies and Department Chair at San Jose State University.
“In our previous surveys of Santa Clara County, we were surprised at how many burrowing owls we found wintering here in these higher elevation areas,” Trulio said. “Unfortunately, when summer came, we didn’t see any of these birds staying to breed.”
Local agencies have come together to support this initiative. “What has become clear through our partnership with Lynne Trulio and the Habitat Agency, for burrowing owl conservation to work, restoration needs to occur on permanently protected lands,” says Galli Basson, Resource Management Specialist with the Open Space Authority. “We are in a unique position to have lands that meet the criteria for breeding habitat. As an agency that works to preserve natural resources in this county, we feel we can support efforts to try to save a species in peril through our lands.”
Previous research on burrowing owl behavior informed the construction of these habitats. Burrowing owls like short grass habitat. Grazing is a good way to achieve this and the Open Space Authority is keeping the site actively grazed. The Authority is also working to maintain good ground squirrel numbers, another feature attractive to the owls. Habitat management and other artificial burrows will be set up along the San Francisco Bay at Shoreline, in Mountain View. The burrows will be monitored through the winter and into the spring to document usage and watch for locally-identified banded birds.
“We know that the work to restore owl populations is experimental and may not be successful, but we must at least try. If the project is successful, we are in a position to share information about this unique and charismatic species with our public, connecting people with nature,” said Basson.
In June 2019, Coriolis Films LLC released a short documentary following this study and its successes so far in using methods that will hopefully increase the survival of burrowing owls around the Bay Area. Check it out!