Safe for Us, Safe for Them: Glass for Birds, Turtles and Other Wildlife

Safe for Us, Safe for Them: Glass for Birds, Turtles and Other Wildlife

June 26, 2024

Learn how today’s windows and doors can show care for animals through specialized designs and features—including bird glass and turtle glass.

Homes, offices, schools and other buildings are human “habitats” that reflect peoples’ needs, behaviors and culture. But what about the living things beyond humans? Now more than ever, design professionals consider how to better honor the habitats and lifestyles of other species like birds and turtles.

Maintaining a connection to the natural environment and the animals that reside there is not just a thoughtful, eco-friendly sentiment—it also provides physical and mental health benefits. Even from inside, people with views and access to the great outdoors—animals and all—experience uplifting effects.

Today, homeowners, architects and other professionals have glass options for their windows and doors to help protect the birds, turtles and other creatures that define and maintain the surroundings outside the walls of built spaces.

ceiling transom windows


Birds and Beyond

When considering the wildlife that is most directly affected by the glass in windows and doors, birds are likely the first to come to mind.

Everyday encounters with birds make lasting improvements to people’s mental well-being. Many homeowners encourage avian activity by adding birdhouses, birdfeeders and water features to their yards. Just hearing a bird’s song, even when the bird cannot be observed, has been proven to lower anxiety and reduce the effects of other mental health issues.

Birds that live and nest locally often become accustomed to both their natural and built environment. On the other hand, migrating birds are less familiar with the new and expanding structures that interrupt their flight paths.

Along with birds, there are sea turtles, bats, pollinators and other nocturnal animals that are affected by light pollution at night. Reflective and clear glass surfaces can also pose an additional, invisible threat. Thankfully, there are proven glass products and other thoughtful design choices that offer methods to create healthier outcomes for animals and humans alike.

ceiling transom windows


Bird-friendly Solutions

Modern architecture’s beauty is often illustrated by expansive, all-glass exteriors. Whether a home design tends toward contemporary or traditional, homeowners today frequently prefer grand windows and doors.

Sadly, bird-window collisions kill up to 1 billion birds in the U.S. each year. It is second only to domestic cats as a human-caused source of bird mortality. It is also easily preventable.

While there may be a tendency to blame skyscrapers, high-rise buildings account for less than 1% of bird-window collisions. In fact, 44% of collisions occur with homes and buildings standing only one to three stories tall, where the birds are most active. Collisions can occur at any time of the year or day with any type of bird, but the majority are during songbirds’ migration seasons.

When birds see outdoor foliage reflected in the glass or observe plants on the room-side of the glass, they often don’t perceive the glass itself; they only see habitat. To avoid reflections that cause collisions, visual markers are needed on the exterior surface of the glass. To make sure the birds see the warning, these markers need to be high contrast and appropriately sized. They must also be properly spaced so birds do not simply try to fly between them.

The American Bird Conservancy recommends that bird-friendly glass has lines that are at least 1/8-inch wide and dots that have at least a 1/4-inch diameter, spaced no more than 2 inches apart. This “2x2” rule helps protect bird species of all sizes, from the small hummingbirds and kinglets to the large robins and ravens.

ceiling transom windows

Glass manufacturers offer bird-safe patterns for windows and doors. These patterns range in visibility to humans so the view is not obstructed when looking outside. Techniques for creating bird-safe patterns include using a silk-screened ceramic frit on the inner surface of the glass, or digitally printing or etching onto the outside surface of the glass. For existing windows and doors, patterned film may be applied to the exterior surface.

Other design options for muting glass reflections include awnings and other overhangs, screens, shutters, and decorative grillwork or other applied elements that divide a large opening into smaller sections.

Nighttime Neighbors

After sunset, bright electric lights shining through windows and doors attract and disorient migrating birds, sea turtles, bats and pollinating insects. Humans’ natural sleep-wake cycles—often called “circadian” cycles—are also disrupted by artificial light sources at night. Excessive or misdirected outdoor lighting and visible indoor light emitting outside are both labeled as light pollution. Reflective surfaces like glass increase the illumination and can contribute to the issue.

To minimize collisions and confusion during migration, some communities have voluntarily adopted practices to reduce unnecessary lighting. Properties in areas with “Lights Out” policies turn off or dim decorative outdoor lights, rely on motion-sensitive exterior lighting, and close blinds or draw curtains. The International Dark Sky Places program certifies and helps conserve areas that take additional steps toward light pollution reduction.

Dozens of U.S. municipalities have adopted mandatory bird-friendly ordinances. While many follow the American Bird Conservancy’s recommendations, the codes are locally implemented, and additional community guidelines may apply. The U.S. Green Building Council’s guidelines for LEED (Leadership in Energy and Environmental Design) offer a credit recognizing projects that take steps to avoid bird collisions.

expansive multi-slide door

Designated coastal areas also have strict limits on lighting to preserve turtles’ nesting and migration areas. Newborn turtles use the light of the moon reflecting off the ocean to guide their travels back to the sea after hatching on shore. The Model Lighting Ordinance for Marine Turtle Protection not only lists requirements regarding illumination and light fixtures but also details light transmittance for architectural glass. For example, Florida’s model ordinance requires tinted glass on windows, walls, railings and doors facing the sea or perpendicular to the shore where marine turtles nest. The tinted glass must not transmit more than 45% of interior light. Research continues regarding optimal tinting to protect individual species of turtles in their local habitats.

Controlling light through glass ensures multiple different species can safely travel even as cities develop and morph.

expansive multi-slide door


Bountiful Benefits

There is no need to compromise one benefit for another in selecting glass for windows and doors. Many glass types can now meet bird and sea turtle protection ordinances while complying with wind-borne impact ratings, energy efficiency goals and other climate-specific requirements.

Kolbe Windows & Doors individually crafts each order to suit, so every opening can be fine-tuned for optimal performance and an overall harmonious home design. With readily available glass options and thoughtful practices in mind, everyone can have the opportunity to enjoy the beauty and benefits of views and sounds from the outdoor environment while keeping birds, turtles and other wildlife safe.

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