Birds face many threats in urban environments, from collisions with glass windows and buildings to predation by cats. Making buildings bird safe can help reduce these threats and protect local bird populations. This article will explore key considerations for bird safe building design and how to make existing structures more bird friendly.
Why make buildings bird safe?
Up to 1 billion birds die each year in the United States from building collisions, according to the U.S. Fish and Wildlife Service. Birds cannot perceive glass as a solid barrier and often fly directly into windows or become entangled in reflective surfaces. Bright lights and unusual reflections can also disorient birds and cause deadly crashes. Beyond direct collisions, artificial night lighting can disrupt bird migration patterns and increase vulnerability to predation. Making buildings bird safe helps reduce these unintended threats to birds.
Key threats that buildings pose to birds
The three main hazards that buildings create for birds are:
- Glass windows and walls – Birds see the reflection of sky and trees and try to fly straight through. Transparent or reflective glass is especially dangerous.
- Artificial lighting – Bright lights disrupt natural migratory behaviors and circadian rhythms, increasing night-time collisions.
- Building and antenna height – Tall structures interfere with flight paths and migration routes, especially around coasts and wetlands.
These 3 factors result in millions of bird deaths annually and must be addressed in bird friendly design.
Design considerations for bird safe buildings
Here are some key design strategies to minimize bird collisions and fatalities:
Use bird friendly glass treatments
Treat glass to make it more visible to birds. Options include:
- Etching, frosting, or fritted glass – Small dots or lines are etched/printed onto glass. This helps make the surface visible while maintaining transparency.
- Films and decals – Apply patterns like dots, stripes, or abstract shapes onto glass surfaces. Avoid transparent decals that could still give the illusion of clear passage.
- Ultraviolet patterns – Birds see UV light, so UV-reflective films can create patterns humans can’t see but birds can.
Minimize transparent building corners
Glass corners and passageways are especially dangerous areas. Strategies to reduce collisions include:
- Angled glass – Slope glass panes towards the ground or sky so there is no illusion of a clear flight path.
- Opaque facades – Use stone, metal, wood, etc to break up reflective surfaces.
- Interior buffers – Move indoor plants, screens, or netting away from glass to prevent collisions.
Downshield exterior lighting
Prevent light pollution and glow. Use downward-facing, shielded fixtures to direct lighting to where it is needed on the ground. Choose warmer color lights like amber or yellow when possible.
Turn off unnecessary lighting
Reduce overall night-time light usage by turning off decorative and interior lighting when not needed. Use motion detectors and timers. City-wide lights out initiatives during migration periods can also help.
Avoid up-lighting and spotlights
Spotlights, floodlights, and up-lighting can illuminate buildings in ways that attract and disorient birds. Avoid lighting facades, rooftops, and other elevated features unless necessary for safety/security reasons.
Minimize rooftop antennas and decorative spires
Communication towers, antenna arrays, and similar rooftop structures can interfere with bird flight paths and navigation. Consolidate these features when possible and avoid brightly illuminating them.
Making existing buildings more bird friendly
For existing buildings, there are retrofits and upgrades that can reduce bird collisions:
Apply window films
Install bird deterrent films on exterior glass. Many types visually mark the window without reducing light or visibility. Films can reduce collisions by up to 80%, according to Audubon Society estimates.
Add exterior screens
Vertical mesh screens and netting provide a physical barrier between birds and glass while allowing transparency. Screens can reduce collisions by 95% or more.
Install UV patterns
UV-reflective films applied to window glass create patterns only birds can see. This alerts birds to the barrier while maintaining a clear view for building occupants.
Place decals on windows
Decals (like bird silhouettes or abstract shapes) spaced closely across glass help mark windows as solid surfaces. Place decals on the exterior for maximum effectiveness.
Use angled shades/awnings
Shading devices like sunshades, awnings, or louvers positioned at an outward angle can help prevent reflection of sky/vegetation that attracts birds.
Reduce lighting at night
Evaluate evening and night-time lighting usage in and around the building. Dim unnecessary lighting, use motion sensors, and implement a curfew on decorative lighting.
Landscape for birds
Plant native species that provide food, shelter, and resting places for birds. Avoid attracting birds close to building facades with lots of glass.
Monitoring effectiveness
To evaluate the success of bird friendly building modifications, conduct periodic monitoring:
- Document bird collisions – Note locations, dates, and conditions when collisions occur.
- Survey intersection areas – Watch dawn/dusk activity at building corners and high collision areas.
- Compare before/after – Estimate collision rates before and after modifying problem facades.
Ongoing monitoring helps identify where additional improvements may be needed.
Special considerations for high-risk buildings
Certain buildings pose greater collision risks and may warrant additional safeguards like:
Migration corridors
Buildings along coastlines or wetland areas require bird friendly treatments since these are primary migration routes.
Urban areas
Downtown office towers, convention centers, and similar urban structures pose collision threats given their size, glass facades, and lighting.
Low-rise buildings
1-3 story buildings with large expanses of glass also result in high rates of bird impacts.
Green buildings
“Green” buildings meeting sustainability standards like LEED sometimes feature more glass and exterior lighting, requiring bird friendly remedies.
Policies and regulations for bird safe design
To promote bird friendly best practices, some jurisdictions have enacted the following:
- Bird safe building guidelines – Voluntary design guidelines for public and private projects to reduce bird collisions.
- Lighting ordinances – Regulations on acceptable lighting types, illumination levels, fixture angles, and times of operation.
- “Lights out” initiatives – Voluntary programs encouraging buildings to reduce night lighting during spring and fall migration periods.
- Legislation – Laws requiring all new construction and building retrofits over a certain size to incorporate bird collision deterrents.
Architects, builders, and facility managers should be aware of any local bird friendly building requirements.
Bird collision deterrent systems
For large existing buildings where window treatments are not feasible, specialized bird deterrent products are available, such as:
| Technology | How it works |
|---|---|
| Bird deterrent wire | Thin metal wires suspended in front of glass create a physical barrier birds can see. |
| Motorized grids | Motor-controlled wires form dynamic patterns to startle birds in flight. |
| Active visual deterrents | Moving lights or projections create illusions of habitat or predators to frighten birds. |
| Acoustic systems | Speakers broadcast predator calls and other alarming sounds audible to birds. |
These systems are expensive but can reduce collisions without altering building design. Effectiveness varies based on proper coverage and operation.
Conclusion
Protecting birds from building collisions requires a multi-faceted approach. Bird friendly design strategies should be incorporated from the start for new construction. For existing buildings, affordable retrofits like films, screens, and lighting changes can significantly reduce hazards. Ongoing monitoring, high-risk building identification, and regulations and guidelines enable broader adoption of bird safe best practices. Implementing bird collision deterrents demonstrates environmental leadership while saving countless birds from unnecessary tragedy.
