All birders are familiar with the occasional window strike when a bird inadvertently hits a window, and it is easy to prevent these accidental collisions. When a bird deliberately attacks a window, mirror, or other reflective surface over and over, however, unique steps may be needed to protect the bird from itself.
Why Birds Attack Windows
Some bird species are naturally very aggressive and territorial.
When they notice their reflection in a window, mirror, chrome bumper, gazing ball, or similar shiny surface, they assume it is a rival bird and will attack the reflection to try and drive the intruder away. They may fly against the reflection, peck at it, rake it with their talons, or beat it with their wings. They may also strike up aggressive poses and threat postures in front of the reflection between actual attacks. While these actions do not generally cause severe injuries, they can lead to exhaustion that will make the bird more vulnerable to disease, malnutrition, and predators.
While any bird may show a bit of aggression towards a competitor, species that are especially known to attack themselves as reflections include:
- American goldfinch
- American robin
- California towhee
- Chipping sparrow
- Eastern bluebird
- Eastern towhee
- European robin
- Gray jay
- Gray wagtail
- Laughing Kookaburra
- Northern cardinal
The degree of aggression and duration of the attacks will vary for each bird species and even for individual birds. Attacks are most common during the breeding season when birds' competitive drive is highest, and may begin as early as February or March as birds start to claim territory.
Depending on the species, attacks could last just a week or two or may continue until late summer if the species raises multiple broods. Only after the breeding season has ended will the aggression wane unless birders take steps to discourage these confused birds.
How to Stop Bird Window Attacks
Many of the best ways to stop birds from attacking windows are the same methods used to prevent bird window collisions. The key is to break up the reflection the bird sees so it does not feel threatened by a non-existent competitor. Options include:
- Decals or paper shapes placed inside or outside the window
- Strips of tape, plastic, or paper arranged in an irregular pattern
- Soaping the outside of the windows either fully or in a pattern
- Placing a non-reflective screen outside the window 2-3 inches from the glass
- Adding one-way transparent film or opaque plastic to windows
- Repositioning an outdoor plant or flower basket to block the window view
- Closing outside shades or blinds if possible
- Shading the window with an exterior awning to minimize reflections
For the best results, the reflective area should be covered as thoroughly as possible, and using several techniques at once can minimize a bird's agitation.
If there are still mirrored surfaces several inches in size where the bird could spot most of its reflection, it may still feel threatened.
If the bird is attacking a vehicle reflection such as a car mirror or chrome bumper, moving the vehicle to a different area may solve the problem because it will be outside the bird's territory. If necessary, an opaque plastic bag can be wrapped over the reflective surface while the car is parked to keep the bird away. Watching birds carefully can also help create solutions. For example, perhaps a bird only spots its reflection from a particular perch, and removing that perch may keep it from noticing the reflection and feeling threatened.
Another temporary solution to stop a bird pecking windows is to make the area less bird-friendly to encourage the bird to find a less apparently hostile territory for nesting.
Removing birdhouses or several bird feeders, for example, may encourage aggressive birds to find a different area for raising their families. While birders may miss their company, the birds will feel safer in an area away from harassing reflections.
NOTE: It is a violation of the Migratory Bird Treaty Act and similar legislation in many countries to capture or harm a bird, its nest, or its eggs, even with the best intentions. The bird should never be harmed in order to stop it attacking its own reflection.
Watching a bird fruitlessly attack its own reflection over and over can be distressing for a birder, and doing so is exhausting and stressful for the bird. Knowing why birds attack windows and how to stop them can help birders provide a safe, hospitable environment for backyard birds to enjoy.