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How to Stop Birds Attacking Windows (Why Do Robins Knock on Glass?)

I have "green-fingers," and love my garden. I enjoy watching wildlife and being outdoors.

A White Wagtail attacks its own reflection in a car's wing mirror.

A White Wagtail attacks its own reflection in a car's wing mirror.

Unusual, Aggressive Bird-Pecking Behavior

Have you ever been sitting quietly at home or in your car when a bird starts to attack the window? A robin recently used my living room window as a target and flew repeatedly at the glass. These aggressive attacks on a windowpane or car wing-mirror can last from 10 to 20 minutes. The same bird may repeat this action several times a day, and this strange behavior can last for several weeks.

To prevent a bird from attacking your window you need to break up the reflection of its image, so it doesn't think it's seeing a competitor. Some of the best ways to do this are given below.

Ways to Stop a Bird From Attacking or Pecking at Your Window

  1. Use highlighters to draw a grid on your window: This is a great method. It works immediately and is recommended by the Texas Parks and Wildlife Service. Birds can see the highlighting, but it is barely visible to humans.
  2. Cover up the window: You could break up reflections by leaving the window dirty, or by soaping it over, or by using decals. This doesn't really work and stops light from entering the room.
  3. Use stick-on deflectors or shiny objects (old CDs) to break up reflection and distract: Shiny hanging objects aren't very effective, but stick-on deflectors can work and are easy to apply.
  4. Close exterior shades and blinds: This is not really an effective solution as you are sacrificing daylight and views for the sake of preventing birds pecking at the windows.
  5. Shade the window with an awning: This may work as it breaks up reflections, but can be an expensive option.
  6. Install wind-chimes or water-fountain as a distraction: These are fun to have but are not an effective bird deterrent.

Draw Gridlines on Your Window Using Highlighters

The best solution I’ve found to this problem is one recommended by Texas Parks and Wildlife Service. It involves drawing grid lines on your windows using fluorescent marker pens (highlighters). It’s cheap and easy to do. It can be done from inside your property so there’s no need to worry about climbing ladders. Best of all, it works!

How It Works:

The pigment in the highlighters can be seen by birds but is difficult for humans to see, so it doesn’t interfere with your view out of the window too much. Drawing a grid of lines with a fluorescent marker breaks up a bird’s reflection, so the repetitive pecking behavior stops. The effect is virtually instant. I use Sharpie Tank Highlighter Marker Pens. Their tanks contain enough ink to draw a grid over the whole window, and their quick-drying ink means that smudging is minimized.

Summary of Texas Parks and Wildlife Service Method

  1. Clean the inside of your windows using a propriety glass cleaner.
  2. Next, use a highlighter to draw a grid of lines on the inside of the affected window. (This is the one that the bird is using for its target practice.)
  3. The horizontal lines should be less than 2” (5 cm) apart. The vertical lines need to be no more than 4” (10cm) apart.
  4. You will need to reapply the grid every week or so as daylight will gradually fade the florescent ink.
  5. That’s it. The job is done. Problem Solved!
  6. Now you can sit back and enjoy birdwatching without the head-banging tactics.

How to Keep Birds From Hitting Your Windows

Stop Pecking by Removing Reflections

You can try to prevent birds attacking panes of glass by covering the outside of targeted windows with non-reflective cellophane. The problem with this is that wind and rain will quickly make the cellophane come adrift and ineffective. A better alternative is to use a decal or an internal window deflector. I find that an opaque bamboo decorative cling film works well.

It can be cut to size and attaches to the glass with no glue. It breaks up the clear view of the window for the birds and stops them striking at their own reflection. At the same time it can be cut small enough not to obstruct your view of the outside. As it clings to the glass by static alone, it's easy to remove if you should want to.

Why Do Birds Fly Into Windows?

Birds fly into windows for three reasons:

  1. They fly into a reflection of a tree or plant thinking its real. When birds see reflection of vegetation or they see through the glass to indoor plants, they fly straight for it at full speed.
  2. Male birds attack their own reflections to defend their territory. These attacks take place most often in spring (the breeding season) and in the fall (when birds are newly arrived on migration from another country). Scientists believe that birds attack their reflection in the glass thinking it's a rival bird.
  3. Night-migrating birds become disoriented by lighted windows. Because these birds navigate by starlight, artificial building lights can confuse them and divert their migration patters. Birds either collide with the windows or they hover around lighted windows until they get exhausted. A single lit city building can kill thousands of migrating birds in just one night.

How to Stop Birds From Attacking Windows

Why Do Birds Peck at Window Putty?

This behavior is commonly carried out by members of the tit family in the autumn and wintertime. Window putty acts as a seal between the frame and house wall, so damage to it can cause rain to enter your home. Birds get linseed or fish oils from the putty to replace a mineral deficiency in their diet. They may also be searching for insects trapped beneath the seal.

The best way to deter birds from attacking your window putty is to apply several coats of gloss paint over it. You can also brush aluminium ammonium sulphate over the frame and seal as birds don't like its taste. Alternatively you can try using a synthetic putty that is made without natural oils.

Is a Bird Hitting a Window an Omen?

There are many superstitions involving birds. Some people believe that a bird hitting a window brings bad luck. They believe that an avian attack is a warning that there are difficult days ahead, even a death in the family. Other folk have a more positive view of the event. They say that a bird flying into your window will bring good fortune and happier times.

Personally, I don't believe in either of these theories. A bird pecking at your glass or car mirror is a natural event, not an omen, and it happens for the reasons outlined above.

A young Gray Jay repeatedly attacks its own image thinking it is a potential rival.

A young Gray Jay repeatedly attacks its own image thinking it is a potential rival.

Territorial Birds That Attack Windows

American goldfinch

American robin

California towhee

Chipping sparrow

Eastern bluebird

Eastern towhee

European robin

Gray jay

Gray wagtail

Laughing kookaburra


Northern cardinal

Northern mockingbird

Ruffed grouse

Song sparrow

Wild turkey

Yellow-rumped warbler


Why is a Robin Attacking Our Window?

It's not just robins that bang into your glass or car wing mirrors. Male songbirds are keen to defend their territory, especially at nesting time. A bird is not accidentally hitting your window, he is attacking it. He thinks he has seen a rival, but it is actually his own reflection.

You can be patient and wait a few weeks until the bird's eggs have hatched and left the nest. At that stage the robin will no longer feel the need to defend its territory. Or, if the bird attacking its reflection is too annoying, you can remove the “intruder” by blocking the reflection using one of the methods described above.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.