Why Birds Fly into Windows and How to Prevent It

Each year, billions of birds worldwide die, after flying into glass windows (or greenhouses). Modern buildings use more glass, so this has increased risks. Glass reflects the sky, trees and gardens. Many birds get confused, and think they are flying into open space or vegetation.

Bright lights at night also confuse birds, making collisions more of a risk. You can also make neighbourhoods more bird-friendly by planting hedges, shrubs and trees. Natural habitats encourage birds to stay in safer areas, instead of busy urban environments.

Check garden-facing windows and conservatories

• Audubon’s guidance on glass collisions highlights reflective surfaces, indoor plants and glass corners as hazards. These features can occur in ordinary homes as well as large buildings.
• Look closely at windows facing trees, hedges or feeding areas. Conservatories, greenhouses and glazed extensions deserve attention because they combine large panes with views of vegetation.
• Glass balustrades and transparent screens can also obstruct routes that appear open. Meanwhile, corner windows may offer a misleading view straight through a building.
• Walk around outside at different times of day. Reflections change with sunlight, so a window that looks harmless in the morning may mirror a tree later.

Turn off lights when not in use

Turning off lights won’t stop all bird strikes. But it does help:

• Turn off indoor and outdoor lights when not needed.
• Close curtains or blinds at night.
• Use desk lamps instead of lighting whole rooms.

Use Feather Friendly visual markers

• Feather Friendly (sold in the UK at Etsy) makes excellent visual markers, which you tape onto windows, so birds can see them, but makes not much difference in view to humans.
• Outside treatments are generally more visible to birds than objects behind reflective glass. Cover the full hazardous pane, including corners and edges.
• The Cornell Lab’s window-treatment advice recommends spacing painted or film patterns about 5 cm apart across the whole surface. Follow each product’s spacing and placement requirements.

Place feeders where birds can’t build up speed

• Birds Canada recommends placing feeders within 1 m/3 ft of a window, so birds cannot build up enough momentum to fly into windows.
• Environment Canada notes that the evidence for ‘farther than 10m/30ft’ is not as firm as people often claim. Cornell says the feeder-distance rule should not replace making glass bird-friendly.
• Avoid landscaping walkways which could funnel birds towards glass.
• Place feeders at least 5/6 feet above ground (away from cats) and sheltered from strong wind/sun, with a 360-degree view to spot predators.
• The American Bird Conservancy’s collision-prevention guidance puts making glass visible at the centre of prevention. Feeder positioning should support that work.

Choose bird-friendly glass

Bird-friendly glass is one part of bird-safe design, especially new builds. BirdDivert is a UV-based bird collision deterrent treatment applied to glass. It’s like an UV-based alternative to Feather Friendly visual markers (so birds can see it, but it does not affect light for humans).

Other solutions are films, markers, screens, and other treatments. For more info on ‘bird-friendly glass’ visit Pilkington and Guardian Glass.

Share practical guidance with decision-makers

• Daniel Klem Jr’s Solid Air draws on more than 40 years of research into bird-window collisions. It’s useful reading for people responsible for buildings.
• Timothy Beatley’s The Bird-Friendly City looks at practical ways towns and cities can support birds, including changes to buildings and public spaces.
• For shared sites, the Bird-Friendly Campus Toolkit provides guidance that schools, workplaces and community organisations can discuss.
• Bring clear photographs and a proposed solution to conversations with landlords or councils. Show which surface needs treatment.

What to do if a bird hits a glass window

If you find a stunned bird:

1. Gently place it in a ventilated cardboard box or a clean paper bag with air holes. Line with a soft cloth (no tassels). If you have no box, a clean paper bag with ventilation holes will do.
2. Keep the container somewhere dark, quiet and warm.
3. Do not give the bird food or water.
4. As stunned birds may still have internal injuries if they fly away, a safer recommendation is to place the bird in a dark ventilated container and contact a licensed wildlife rehabiliator or local wildlife rescue as soon as possible. Find more info at FLAP.

Start a local FLAP program

FLAP (fatal light awareness programs are started by local communities to reduce bird deaths. They encourage local people to turn off lights when not in use, and promote safer window treatments like above.

You can order a starter pack and take a local survey. Then get people on board to share information and solutions to help. With neighbours, schools and businesses.