Cover photo: © Nathan Rupert, 2010, Flickr Photo Album, some rights reserved.

Quick Facts

  • The western burrowing owl is a small species of diurnal owl, meaning that it’s active primarily during the day.
  • The burrowing owl used to be common in the Bay Area, but habitat loss has caused a steep decline in their populations over the last 30 years.
  • Local conservation groups are working to improve habitats to make them more attractive to owls, and are working on monitoring sites known to have owls.

 

Nestled on the edge of a corporate development next to the entrance to a local wildlife preserve lies a small, fenced-off lot of short grass. Here, after minutes of scanning small mounds of dirt, Dan and I encountered our first burrowing owls. An adult sat hunkered down, directly next to a young owl that was curiously peering back at me with large, yellow eyes. With this developed backdrop, it is difficult not to question the fate of this charismatic species.

A Bay Area Species in Peril

The western burrowing owl is a diurnal owl, meaning that it’s active during the day. It’s fairly small, standing at about 10 inches high. True to their name, they nest and reside in burrows in the ground – relying on sites that have already been excavated by burrowing mammals such as the California ground squirrel. They can often be found standing vigilant outside of their burrows during the day.

This endearing bird was once a common bird in the South San Francisco Bay Area. In the mid-1980’s their population was estimated to be about 640 individual birds – with three-quarters of the population residing in the South Bay alone. Today, their population has been reduced to isolated breeding and overwintering populations (overwintering populations migrate to the Bay Area during the winter to escape cold temperatures in their other homes). In 2017, the South Bay reported just 64 adults at 5 breeding sites.

Burrowing Owls Logo

An adult and juvenile western burrowing owl in the South Bay.

Habitat Loss and Evictions

Habitat loss is the main threat that these owls face. The South Bay was once host to native grassland habitats; however, housing and other commercial developments to address a booming human population have outcompeted the owls for space. The East Bay is facing similar problems – areas that overwintering owls need to be successful have rapidly disappeared, putting stress on their populations.

Even at sites where the owls reside, the active removal of burrowing owls takes place. Developers that are initiating projects at known burrowing owl sites will hire contractors to install one-way doors at burrowing owl sites – allowing the owls to leave their burrow, but not to re-enter.

These “evictions” are rendered legal because individuals or nests are not harmed. However, many groups criticize the practice since there is no monitoring of the evicted birds after the traps are installed. Burrowing owls have high nest site fidelitymeaning that they have high rates of returning to the same breeding site, and even specific burrow, year after year. With the evictions taking place without long-term monitoring of the displaced owls, the effects of practices such as these are unknown and the evictors are not held accountable.

Bay Area Organizations Band Together for Owls

Efforts to increase the population of breeding burrowing owls in the South Bay are currently being implemented. A number of South Bay organizations have banded together to increase the population of breeding owls at Warm Springs in Fremont. Based on the outcome of their efforts, they will apply what they’ve learned at this site to the management of other sites in the South Bay. Similarly, the Santa Clara Valley Audubon Society is working in Alviso, a neighborhood in San Jose, to provide suitable habitats for the owls. The group works to install artificial burrows and mow the area to keep vegetation short.

In the East Bay, the Golden Gate Audubon Society, the City of Berkeley Marina and the Shorebird Nature Center have joined forces to create the Golden Gate Audubon Burrowing Owl Docent Program. The program focuses on raising public awareness about keeping dogs on-leash to help protect the overwintering owls that use the areas in the East Bay. Docents also keep track of the burrowing owl numbers in their area – allowing for long-term population data.

Efforts such as these provide hope for burrowing owl populations, yet their fate is still undecided in the face of the rapidly expanding Silicon Valley.

For more information on how to volunteer for the Golden Gate Audubon Society’s Owl Docent Program, please visit this page and scroll to “Train to Become a Docent” towards the bottom of the page. For more information on volunteering with the Santa Clara Valley Audubon Society doing habitat restoration at Alviso, please visit this page.

Resources

Posted by Taylor Crisologo

Taylor studied biology at Cornell University, where she worked with the Cornell Lab of Ornithology on projects ranging from breeding herring gulls off the coast of Maine to dancing lyrebirds in Australia’s Blue Mountains. When she’s not researching great places to experience Bay Area nature, you can find her birding or reading a book at home with her husband and their two indoor cats (Max and Penelope).

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