Songbirds and Killer Windows

Glass lets the sun in and keeps out the cold — and the heat. It also makes a near-perfect mirror when conditions are right. To a songbird, a patch of reflected sky or foliage in a wall can mean a broken neck and death.

According to the American Bird Conservancy, approximately one billion birds die each year from window strikes in North America alone. In Canada, estimates put the toll at around 25 million birds per year — and 90% of those collisions happen at single-family homes, not skyscrapers. Our homes and buildings are using more and more glass to create bright, open living spaces, but resident and migrating songbirds pay dearly for our comforts.

Why Can’t Birds See Glass?

Birds have very different vision from humans and can detect ultraviolet light. The problem with glass is that a reflective window shows birds a convincing mirror image of the sky and surrounding vegetation — indistinguishable from the real thing. Some of the most effective modern solutions exploit this: they apply UV-reflective patterns to the glass that are nearly invisible to humans but clearly visible to birds.

Who Is Most at Risk?

Small, quick birds — mainly songbirds and thrushes — are the most susceptible to window strikes. Lighter birds sometimes bounce off and survive the impact, but larger birds such as the American Robin are more likely to suffer severe injury. In many cases, it is not the impact itself that kills a bird but the onset of shock and its complications. A stunned warbler may freeze where it fell — in a snowdrift, on the ground within reach of the neighbourhood cat — unable to respond normally. Shock leaves a bird vulnerable to its environment, and in our urban and suburban settings, the odds are rarely in its favour.

The Most Important Rule: Spacing

Whatever treatment you choose, one rule overrides everything else: leave no gap larger than 5 cm (2 inches) in any direction between markers. Birds will attempt to fly through any space they think they can fit through. A single decal or silhouette in the middle of a window doesn’t reduce strikes — it may not even slow them down. Coverage is everything.

What Doesn’t Work: The Hawk Silhouette

The hawk or Merlin silhouette has been used for decades as a window deterrent — including on this site. Research has shown it is not effective. Birds do not avoid glass because they see a predator; they avoid it when they can see it is a solid barrier. Safe Wings Ottawa reports that finding a hawk silhouette on a window is a reliable predictor that bird strikes are happening there. A few decals in the centre of a pane give the homeowner false confidence while doing little for the birds.

The Merlin silhouette printable that appeared in the original version of this article has been retired.

What Works: Proven Products

DIY Solutions

Don’t want to buy anything? Several effective treatments can be made at home for next to nothing. The same spacing rule applies: no gaps larger than 5 cm (2 inches) between markers.

• Tempera paint — paint a pattern of dots or stripes directly on the outside of the glass using a brush or sponge. Tempera washes off easily with water, making it ideal for renters or for seasonal use. Any colour works; high-contrast colours are most visible to birds.
• Stencil and paint pen — cut a 5 cm × 5 cm stencil from cardboard and use an exterior paint pen or chalk marker to apply a repeating pattern across the pane. More precise than freehand, and the result can look quite tidy.
• Dot foam roller — cut notches into a foam paint roller at regular intervals and roll a dotted pattern across the glass. Use exterior paint for a permanent result, or chalk marker or tempera paint for a removable one. Covers a large window quickly.
• Paracord curtain — hang lengths of 1/8” paracord vertically in front of the window, spaced no more than 10 cm (4 inches) apart. The cords hang loose, so birds see and avoid them without impact. No tools needed and easily removed. This is the same principle as the commercial Acopian BirdSavers.

Stop Bird Collisions has video tutorials and step-by-step instructions for all of these.

Other Things You Can Do

• Move feeders close or far: Place feeders and bird baths either within 1 metre of a window (so birds cannot build dangerous momentum) or more than 10 metres away (so they approach from a direction away from the glass).
• Pull the blinds: Leaving interior blinds or curtains partially closed on problem windows reduces the mirror effect as seen from outside.
• Skip a window wash: A light film on the outside of the glass breaks up the reflection enough to give birds a visual cue. It is not a solution on its own, but every little bit helps on a problem window.
• Lights out at night: During spring and fall migration, turn off or dim exterior lights and indoor lights visible from outside. Artificial light at night disorients migrating birds and draws them into built-up areas.

Learn More

I am not an ornithologist or a building safety expert — the information in this article draws on the work of organisations that have studied this issue closely. If you want to go deeper, these are the best resources I know of:

• FLAP Canada — Fatal Light Awareness Program, Canada’s leading organisation on bird-safe buildings. Excellent practical guides and product information.
• Birds Canada — Canadian-specific guidance, including product recommendations and a Feather Friendly discount code.
• American Bird Conservancy — the most comprehensive resource available, with a searchable database of products and treatments for both homes and commercial buildings.
• Stop Bird Collisions — an excellent practical guide covering both purchased and DIY solutions, with video tutorials for making your own treatments at home.

So the next time you wash your windows, remember you are also making it harder for birds to see them. “Perhaps that is why seagulls and pigeons paint them for us.”

Last updated: May 2026

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