April 3, 2026
San Mateo County Board of Supervisors
500 County Center
Redwood City, CA
Re: Item 7, April 7 Agenda: Design Review Regulations – Bird Friendly Design Standards
Dear President Corzo and Members of the Board of Supervisors,
The undersigned organizations support the bird-friendly glazing standards proposed by staff in the Design Review Ordinance Update (Item 7 on April 7, 2026 Board agenda).
The San Mateo County Bird Alliance, Green Foothills, the Sierra Club Loma Prieta Chapter, the Santa Clara Valley Bird Alliance, and the American Bird Conservancy work to protect birds, biodiversity, and natural resources through science, policy, and community engagement.
Scientific research consistently shows that bird collisions with glass are a major source of human-caused mortality. In North America alone, hundreds of millions of birds are killed each year due to collisions with buildings. Collisions occur wherever birds are active, not only in dense urban cores but also in suburban areas with trees, landscaping, and nearby open space. In these environments, most collisions occur at tree-canopy height, generally from ground level to about 60 feet, where birds are actively foraging and moving through habitat. Transparent and reflective glass creates the illusion of open sky or vegetation, leading birds to attempt to fly through or into these surfaces. As a result, even relatively small buildings and common features such as glass railings, corners, and fly-through designs can pose significant risks. These risks are especially pronounced near waterways, the coastline, open water, open space, and hillside areas, where bird activity is concentrated and collisions are more likely.
The proposed standards are reasonable, feasible, and consistent with both regional practice and emerging national building standards. They provide clear, objective design criteria that can be readily implemented.
Bird-friendly design standards similar to those proposed by staff are already widely adopted across the Bay Area. San Francisco, Mountain View, Berkeley, Alameda, San José, Palo Alto, and Cupertino have all adopted or incorporated bird-safe design requirements in their codes or policies. Together, these jurisdictions demonstrate a clear regional trend toward practical, implementable standards that reduce bird collisions without impeding development.
The proposed standards are also aligned with national green building guidance. In January 2026, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) adopted Addendum “o” to Standard 189.1, introducing bird-friendly glazing as part of high-performance building design. That standard applies broadly to new construction, additions, and alterations, and addresses key risk features such as glazed corners, fly-through conditions, and areas adjacent to vegetation or water.
In key respects, the staff proposal is more moderate than the ASHRAE framework. It applies at a higher 50% glazing replacement threshold, includes reasonable exemptions, and relies on well-established treatment methods such as exterior-applied patterns, low-reflectance materials, and screens or shading devices.
These are standard, widely used solutions. The staff proposal reflects a growing consensus among cities, scientists, and the building industry, and provides a clear, workable path to reduce bird collisions without adding undue burden.
We respectfully urge the Board to adopt the bird-friendly glazing standards as proposed by staff as part of the Design Review Ordinance Update.
Thank you for your leadership.
Sincerely,
Lennie Roberts
Legislative Advocate
Green Foothills
Chris MacIntosh
Chair, Conservation Committee
San Mateo County Bird Alliance
Dashiell Leeds
Conservation Coordinator
Sierra Club Loma Prieta Chapter
Shani Kleinhaus
Environmental Advocate
Santa Clara Valley Bird Alliance
Kaitlyn Parkins
Glass Collisions Program Coordinator
American Bird Conservancy