Why Do Cardinals Keep Attacking My Window?

Many territorial birds become highly aggressive when they spot individuals of the same species within their domain. As a result, they often attack reflections in windows or car mirrors, mistaking them for intruders. The Northern Cardinal and the American Robin are among the most frequent offenders, and males are usually the ones most likely to display this behavior. Occasionally, female Northern Cardinals may engage in this type of attack as well.

The spring and summer months are the breeding season for cardinals, and their defensive behaviors are particularly intense during this time. This type of aggression is more common in these months. In the wild, when a male cardinal spots another cardinal in its territory, it will first issue a warning call, fly to a branch to sing, or even lower its crest and emit a "pee-too" or "chuck" sound. If the intruder does not leave, the male cardinal will lower its body, open its beak, flap its wings, and make various sounds. If the intruder still doesn’t leave, the cardinal will advance to chase the intruder away, often causing it to flee before a physical confrontation.

While wild cardinals typically exclude neighbors and display territorial behavior, direct physical fights are uncommon. The confrontations usually last about 30 minutes, but actual physical combat lasts only a few seconds. However, reflections in windows don’t leave and don’t respond with calls. To chase away the reflection, the cardinal goes into full combat mode, striking the glass. But since the reflection doesn’t fly away or engage like another bird would, it only mimics the cardinal’s actions. Each time the cardinal attacks, the reflection remains steadfast. The cardinal, determined to drive the reflection away, can continue attacking the window for weeks.

If the cardinal targets one window, solving the issue isn’t too difficult. Here are a few strategies:

Reduce Window Reflection: You can decrease the reflection by applying frosted stickers or dark cloth on the outside of the window. Alternatively, you can use static window decals, shading nets, or bird-specific window stickers (such as those with a grid pattern) to prevent the cardinal from seeing its reflection.

Distract the Bird: Hang wind chimes, ribbons, or other items that move with the wind on the window to distract the bird. You could also place a bird feeder or other attractants nearby to draw the cardinal’s attention away from the window.

Interesting Fact:
Some birds, especially those in the Crow family, can recognize that the image in a mirror is just a reflection and not a real bird. An experiment showed that when a 

magpie's throat was painted with bright yellow or red paint and then shown a mirror, it scratched at the areas on its body where the paint had been applied. However, when the same bird was painted with black paint that matched its natural throat color, it didn’t react to the reflection. Currently, the ability to recognize one's reflection is known to exist only in primates, dolphins, and elephants. Unfortunately, Northern Cardinals and American Robins lack this ability.

To help keep cardinals safe and redirect their energy, consider using the Smart Bird Feeder. This innovative feeder provides a safe feeding space and can draw cardinals away from windows, while allowing you to monitor their activity through a convenient mobile app.