How to stop birds hitting your windows.
Birds don't understand glass. They see reflected sky and trees, or a clear path through to more garden. The fix is to make the glass look like a barrier, and the details of how you do that matter more than what you use.
Why birds hit windows
The US Geological Survey lists three causes: reflection (the glass mirrors vegetation or sky), transparency (a bird sees habitat through a corner or a run of windows and tries to fly through) and territorial behaviour, where a bird attacks its own reflection, often in breeding season.
The rule that matters: spacing, outside
Every major source agrees on two points:
- Put markers on the outside of the glass. Reflections form on the outside surface, so markers on the inside can disappear behind them.
- Cover the whole pane in a tight pattern. The US Fish & Wildlife Service and American Bird Conservancy recommend markers no more than about 5 cm (2 in) apart. Audubon describes a "2×4" rule: about 5 cm apart horizontally and 10 cm (4 in) vertically. A single sticker in the middle won't work.
What works
- Dense decals or dots on the outside, following the spacing rule.
- Tempera paint or soap patterns: cheap, temporary and easy to wash off.
- Hanging cords outside the window, no more than about 10 cm (4 in) apart (Audubon).
- Insect screens or netting fixed a little way out from the glass.
- External film designed for bird safety.
- Blinds or curtains help most where the problem is see-through glass.
Our Leaf Window Decals are a light-touch option for breaking up a reflection near a feeder. To meet the spacing rule across a large pane you'll need several sets, or combine them with one of the options above.
Feeders and window strikes
Audubon suggests feeders either very close to the glass (within about 50 cm, 1.5 ft) or well away. Birds leaving a feeder that's right on the window can't build up enough speed to be badly hurt. That's one reason window feeders like our Classic Window Feeder sit directly on the glass. Our earlier piece on window feeders and strikes goes deeper.
If a bird hits your window
If it's stunned, keep pets inside and leave it somewhere quiet and safe to recover. If it's injured or doesn't recover, contact a local wildlife rescue (in Australia, your state's wildlife carer network; in the US, a licensed wildlife rehabilitator).
Frequently asked questions
Do window decals stop bird strikes?
Yes, if they go on the outside of the glass and cover the whole pane in a tight pattern, about 5 cm (2 in) apart. One or two decals won't help much.
Should decals go inside or outside the window?
Outside. Reflections form on the outer surface and can hide markers placed inside.
Why does a bird keep attacking my window?
Usually it's defending its territory against its own reflection, often in breeding season. Cover the outside of that pane to break up the reflection.
Do window feeders cause bird strikes?
Feeders very close to the glass are considered lower risk, because birds leaving them can't build up much speed.
Sources
- USGS: How can I stop birds from repeatedly hitting my windows?
- US Fish & Wildlife Service: Bird-friendly window dimensions
- American Bird Conservancy: Solutions for homes
- Audubon: What does 'bird-safe glass' even mean?
Written by the Perchwild team. Questions? Write to us.
