Collisions with buildings are killing millions of birds nationwide. A dark-sky movement to save them is sweeping the Bay Area.

Collisions with buildings are killing millions of birds nationwide. A dark-sky movement to save them is sweeping the Bay Area.

Shani Kleinhaus can quickly recognize a window that kills birds.

“Often, I can see the pattern of the collision on the window, like the bird’s outline and wing shape,” she says.

Where she doesn’t see such evidence is at the Environmental Education Center on McClellan Ranch Preserve in Cupertino — right next to the offices of the Santa Clara Valley Audubon Society. Kleinhaus, who serves as the chapter’s environmental advocate, points to thin vertical black lines that streak the building’s windows.

“The important thing is to make the glass visible to birds with some kind of visual cue,” Kleinhaus explains. “In this case, they used this ceramic pattern of dark lines in the glass, but there are all kinds of patterns you can use.”

The center’s outdoor lights, too, have been designed with migrating birds in mind.

“You can see it’s very targeted,” says Kleinhaus. “It only highlights the pathway that goes to the door. If you step a few feet away, you can’t see the bulbs because they’re shielded downward.”

Nobody knows exactly how many birds are killed each year by crashing into buildings, but in 2014, Smithsonian researchers estimated the number at between 365 million and 1 billion birds annually in the United States alone.

Thanks largely to the efforts of Kleinhaus and the Santa Clara Valley Audubon Society, working with the Loma Prieta Sierra Club chapter, a movement is taking root across the Bay Area to stem these avian deaths through local regulations.

Environmental advocate Shani Kleinhaus of the Santa Clara Valley Audubon Society looks over bird-friendly windows at the McClellan Ranch Preserve on Monday, Dec. 4, 2023, in Cupertino, Calif. Vertical lines embedded in the window glass are used to reduce bird strikes. (Aric Crabb/Bay Area News Group) 

Pioneered in Cupertino in 2021, this effort has two prongs: dark-sky ordinances, which limit and modify the lighting allowed on private premises; and bird-friendly design ordinances, which require new buildings to make windows more visible to migrating birds.

With multiple cities in the region considering the measures, the Bay Area is becoming a national leader on the issue.

For more than a century, ornithologists have known that buildings with bright lights pose a danger to birds. In 1917, Walter Albion Squires and Harold E. Hanson of the Audubon Society of the Pacific in San Francisco surveyed the keepers of 36 lighthouses across California. Most reported no bird deaths, but the keeper of the Point Arena lighthouse in Mendocino County told them that up to 30 birds could perish on calm, dark nights.

“The larger birds are killed by flying violently against the glass or other portions of the lighthouse structure; small birds are also sometimes killed in this way, but sometimes also they become confused, and fly about and against the lantern until they fall from exhaustion,” Squires and Hanson wrote.

Today, birds can be tracked by radar, allowing scientists to understand the broader impact of bright lights on their annual movements — especially the fall migration, which occurs mostly at night.

“Migrating birds are attracted to lights, so instead of going where they might have gone historically, they’re using slightly different routes,” says Travis Longcore, an environmental scientist at UCLA and science director of the Urban Wildlands Group.

These detours through populated areas are far more perilous. “The birds are much more likely to end up dead on the ground in a city or a town than they are where they probably should be, out in some undeveloped area,” Longcore says.

The most gruesome reports of bird deaths come from skyscrapers in eastern cities, where thousands of migrating birds have died in a single night. But this is probably just the tip of the iceberg, according to Longcore. “Probably the majority of this is happening at low-rise buildings, not the high-rises that are in the news from Philadelphia or New York,” he says.

It took several years of persistent advocacy for Kleinhaus to put the issue on the political agenda across the Bay Area.

“I met Shani in 2017 when I began volunteering for the Silicon Valley Audubon Society,” says Dashiell Leeds, now a Sierra Club advocate. “One of the first things she had me do was write an article in their monthly newsletter about dark-sky measures.”

In 2021, Kleinhaus and Leeds had their first major success when Cupertino’s City Council passed a combined bird-friendly design and dark-sky ordinance.

The measure requires new building developments in the city to comply with requirements on outdoor lighting that mitigate harm to birds. Beyond reducing overall nighttime lighting, it requires lights to be shielded from above so they point downwards and don’t flood onto neighboring properties. It also requires lights with warmer hues, since blue-heavy LEDs are particularly disruptive to flight. The ordinance also requires larger new buildings to make windows visible to birds, usually by printing a faint but regular pattern of opaque markings on the glass.

After Cupertino took action, Brisbane adopted a dark-sky ordinance and rules are now in various stages of development in Los Altos, Palo Alto, Mountain View and Sunnyvale, in addition to a broader ordinance covering the whole of Santa Clara County’s unincorporated areas.

On Oct. 24, the Los Altos City Council discussed the dangers of a brightly lit night sky. Planning Director Nick Zornes presented the proposed ordinance to limit nighttime lighting and require warmer-colored LEDs.

Environmental advocate Shani Kleinhaus of the Santa Clara Valley Audubon Society looks over bird-friendly windows at the McClellan Ranch Preserve on Monday, Dec. 4, 2023, in Cupertino, Calif. Vertical lines embedded in the window glass are used to reduce bird strikes. (Aric Crabb/Bay Area News Group) 

The birders were out in full force at the meeting, with several speakers in favor of the drafted ordinance, or pushing for it to go further. Leeds and others urged the council to add bird-friendly design to their plans. The council unanimously decided to forward the ordinance to the city’s Environmental Commission to work out the details and return with a proposal.

“Every city counts,” Leeds said after the meeting. “Each jurisdiction that does this can inspire a neighboring jurisdiction.”

On Nov. 16, the Brisbane City Council voted unanimously to adopt its dark-sky ordinance, which restricts light pollution, but not window design. “I, too, look out my front windows, and I see some apartment buildings on the other side of the hillside that are lit up like it’s Christmas,” said Mayor Pro Tempore Terry O’Connell, speaking in favor of adoption.

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To this point, there doesn’t seem to be any locally organized opposition to the ordinances. In the Los Altos and Brisbane meetings, the only public comments favored the protections. The activists argue that the measures are low-hanging fruit for conservation because there are limited drawbacks.

“It’s much easier to solve than climate change. You just have to turn the lights off. So why don’t we?” Kleinhaus asks.

Cupertino has so far had no pushback from developers, says Mayor Hung Wei. But it’s still too early to know for sure.

“We haven’t had much new development yet,” Wei says. “I think practically speaking, we will know more when things are really being built over the next eight to 10 years.”

Leeds says that he was drawn into the dark-sky movement by the opportunity to make a real difference at the local level.

“This is how I personally cope with having these big imminent issues hanging over my head all the time, like climate change and destruction of the biosphere,” he says. “The more you zoom out, the more powerless you feel. So I think the best way for me to engage in life as an activist is just to influence things within the sphere of my control.”