Simple design choices can save a billion birds from deadly collisions.
By Rose Morrison, managing editor of Renovated and The Landscape Guide.
Birds migrate using starlight and magnetic cues as their guides. When these guides meet urban landscapes and backyard fences, the results are often deadly. Avian collisions with man-made structures greatly affect bird populations and erode biodiversity. However, most impacts stem from design choices that can be addressed without sacrificing security. Fortunately, there are practical and research-backed animal and bird-friendly fence solutions for property owners, designers and policymakers seeking safer spaces for both wildlife and people.
Bird Collisions and Their Consequences
A 2024 study in PLOS ONE found that building strikes alone kill more than 1 billion birds every year in the U.S. — far exceeding earlier estimates of between 365 million and 988 million.
Roadways compound the damage — driver-reported data from 2020 to 2022 suggest roughly 96 million birds die annually in vehicle collisions across the continental U.S. Urban lights intensify the threat. Surveys in Dallas and other major flyways link excessive night lighting to soaring collision counts during migration.
Species that migrate long distances, hunt insects in woodlands or travel at low altitudes suffer disproportionate losses. Their disappearance could eventually weaken climate-resilient ecosystems worldwide.
Many of these fatalities occur around low-rise commercial blocks and single-family homes — about 56% and 44% respectively — while downtown skyscrapers account for less than 1%. Collision monitoring in the 2024 Lights Out Philly program showed a 70% drop in strikes at one participating building once nonessential night lighting was switched off.
Beyond biodiversity, the avian deaths also carry a price tag, as birds that pollinate and control pests support U.S. crops worth around $34 billion per year. That means each collision chips away at ecological balance and food security.
The Science Behind Bird Collisions
Bird eyes evolved to read horizon lines and vegetation, not reflective glass or tightly spaced wires. Windows mirror the sky and trees, and shiny metal or monofilament fence strands disappear at flight speed. Artificial light further disorients nocturnal migrants, drawing them toward buildings where transparent corners create the illusion of open air. Even drifting cloud reflections on glass can distort depth perception and lure birds to misjudge distance and collide at full speed.
What Makes a Bird-Friendly Design?
Effective collision prevention starts with visibility, permeability and context. Care must be taken to maintain territorial security for people without introducing lethal barriers for wildlife. Around the world, the most successful designs share four traits:
- Contrast and pattern: Visual cues — such as fritted glass dots or bright fence markers — alert birds early enough to veer away.
- Safe passing space: Gaps under bottom wires allow fawns to crawl, while vertical spacing helps cranes and grouse fly through.
- Strategic landscaping: Native plants and trees provide feeding stations that steer birds away from reflective walls.
- Adaptive lighting: Motion-activated or downward-pointing fixtures help reduce nocturnal disorientation.
Case studies from Toronto’s retrofit of bus shelter glass and Germany’s low-contrast power line markers confirm that small pattern changes can cut mortalities by half or more without diminishing security or aesthetics.
Developers also gain a financial benefit when bird-friendly features are planned early. Columbia University’s Sustainable Investing Research Initiative found in 2024 that projects incorporating avian impact assessments at the concept stage sidestepped costly permitting delays and rework, while delivering asset value boosts and community goodwill.
Best Practices and Innovations for Bird-Friendly Fencing
Before sinking a single post, property owners should confirm legal boundaries. A property line map or plat — an official drawing that shows length, angles and shared lines — is the easiest way to locate true limits. Copies are available from local assessors.
Many traditional fences rise too high for deer and pronghorn to clear and bristle with barbs or razor wire that may harm owls, hawks and low-flying songbirds. In addition to fences being too high for animals to clear, it’s also important to check local regulations regarding maximum fence heights to ensure compliance. Rethinking height, material and visibility by using the following innovations can help mitigate common hazards:
- High-visibility flags, reflective tags or a white polyvinyl chloride (PVC) sleeve on the top wire can reduce sage-grouse collisions by over 80%.
- A smooth top wire set one meter high, a 12 cm gap to the next strand and a 40 cm wildlife gap under the lowest wire allow pronghorn to glide beneath and elk to hop over with minimal injury.
- Mesh avoidance panels, wood rails or powder-coated aluminum outlast barbed steel and remain visible under varied light.
- Passive infrared sensors tied to perimeter lights or alarms activate only when large mammals approach — providing privacy while protecting birds.
- Thorny shrubs or hedges planted at fence bases discourage climbers, while offering a natural barrier. In wildfire-prone areas, planting fire-resistant native plants like red osier dogwood also helps reduce ignition risks.
Bird-Safe Home and Building Design
Bird-friendly glazing and design details can help reduce avian collisions. Options include:
- Fritted or etched glass: Ceramic patterns baked into the surface break reflections for birds while preserving daylight for human occupants.
- Ultraviolet (UV) reflective coatings: Birds detect UV spectra more vividly than humans, so patterned UV stripes appear solid to them yet transparent to residents.
- External screens or films: Retrofitted adhesive dots with 5 cm x 5 cm spacing block flight paths for small warblers.
- Architectural overhangs: Awnings and louvers cut sky reflections that typically appear at dangerous angles.
Standards are improving. The U.S. Green Building Council’s Leadership in Energy and Environmental Design program made its Bird-Collision Deterrence credit permanent in 2022 and doubled its value to two points in 2025 drafts. Many municipalities now require bird-safe glass. Middleton, Wisconsin, embedded such rules in its 2024 zoning overhaul, while the U.S. Congress is debating the Federal Bird-Safe Buildings Act of 2023.
Mike Quigley, Illinois representative and co-sponsor of the Federal Bird-Safe Buildings Act, says, “Every year, 1 billion birds are killed by collisions with buildings in the United States. To make matters worse, these deaths are preventable. Our bill is a cost-neutral, common-sense solution to this crisis. By incorporating bird-safe features into public buildings, the federal government can lead the effort to save these animals from further endangerment.”
Retrofitting older facades can be quick — polycarbonate exterior panels, anti-collision tape or micro-louver films adhere without major renovation. When paired with smart lighting controls that dim during spring and fall migrations, resident comfort improves and energy costs drop.
Native Landscape Upkeep
Plants can do much of the heavy lifting once they are established, but a few scheduling habits keep habitat and security features in sync. Native shrubs need only light pruning to stay within sight-line limits along fences, and many thrive without extra fertilizer or pesticides, conserving water and labor.
Early-spring thinning prevents dense thickets from obscuring fence markers, while late-summer editing removes aggressive plants that might invite climbing intruders. Fallen berries and seed heads should be left until winter’s end, then composted to avoid attracting rodents.
Policy, Equity and Community Action
Safer skies start at the street level, especially in communities that already carry heavier environmental burdens. In Illinois, roughly two million people live within half a mile of logistics hubs that bring constant diesel traffic and stadium-style lighting.
Neighbors are turning that frustration into action. Cornell University researchers who analyzed 70,000 volunteer collision reports in 2023 confirmed that cities with active citizen-science networks adopt bird-safe ordinances almost 18 months sooner than those without.
Policymakers are listening. During the 2024 spring migration, New York State dimmed nonessential lights on more than 200 government buildings. The Lights Out Texas campaign also urges Dallas-Fort Worth homes and businesses to go dark for 10 critical weeks each year. Combined with tree planting grants, these light reduction policies make neighborhoods far safer for birds.
What Homeowners, Builders and Policymakers Can Do
Bird-friendly designs start with targeted actions that fit into routine maintenance and location planning. These practical steps can help protect property and wildlife in one coordinated effort:
- Audit existing hazards: Walk the property at dawn when reflections are sharp. Note clear glass corners, taut wires and bright fixtures.
- Check the plat: Verify boundaries on the property line map to prevent disputes before installing new fencing.
- Retrofit high-risk surfaces: Apply UV-pattern film or dot decals and add PVC marker sleeves to fence tops.
- Plant native: Choose region-specific shrubs to lure birds away from windows while enhancing security hedges.
- Install smart lighting: Timers and motion sensors balance safety with dark-sky goals.
Free, crowd-sourced platforms make it simple to log every strike and see patterns emerge. The Global Bird Collision Mapper offers a building-level heat map. Its 2023 overhaul added easier edits and group dashboards, making it possible for facility teams to pinpoint trouble facades before the next migration window.
Forward Flight
Imagine schoolchildren tracking returning swallows, architects trading low-cost solutions across countries and scientists feeding open-source collision data into smart city dashboards. Every marker installed or sapling planted becomes a micro-pledge to biodiversity. A design that respects avian flight paths does not need to compromise human safety — it strengthens it.
Visible fences, patterned glass and native plant buffers deter intruders and let birds continue their journeys. By adopting these measures today, communities place themselves at the forefront of climate-resilient living, proving that a safe home can give wildlife room to fly.
About the Author
Rose is the managing editor of Renovated and has been writing in the construction, landscaping and sustainable building sectors for over six years. She’s most passionate about improving environments, reducing carbon footprints and incorporating resourceful methods to promote well-being in the planet. For more from Rose, you can follow her on Twitter and connect on LinkedIn.