Birds frequently flying into windows is a common and often upsetting occurrence, particularly noticeable with cardinals. Understanding why these birds repeatedly strike glass surfaces is important for finding effective solutions that protect them.
Understanding the Primary Causes
One primary reason cardinals, especially males, repeatedly fly into windows stems from mirror-like reflections and their strong territorial instincts. Windows often act as highly reflective surfaces, mirroring the surrounding environment. Birds perceive these reflections as a continuation of their habitat or an open pathway, rather than an impenetrable barrier.
Male cardinals are particularly territorial, especially during the spring breeding season. When a male cardinal sees its own reflection in a window, it perceives this image as an invading rival. This triggers an aggressive response, as the cardinal instinctively tries to chase away the perceived intruder. The bird will repeatedly attack its own reflection, leading to repeated strikes against the glass. This behavior is a natural instinct misdirected by the artificial environment of a window.
Other Contributing Factors to Collisions
Beyond territorial aggression, other environmental factors can lead to window collisions for various bird species. The transparency of glass can create a “fly-through” illusion, especially when windows are on opposite sides of a building. Birds may attempt to fly directly through, mistaking the transparent glass for an unobstructed path.
Artificial lights, particularly at night, pose another risk for migrating birds. Disoriented by urban light pollution, birds can be drawn off their migratory paths, making them vulnerable to collisions. Windows located near bird feeders or bird baths can also lead to collisions when birds are startled. Additionally, reflections of dense vegetation in windows can give the illusion of a safe landing spot, enticing birds to fly directly into the glass.
Preventing Window Strikes
Several practical strategies can help reduce bird window strikes. The primary goal is to make the glass visible to birds or to break up misleading reflections. Applying visual markers to the outside of windows is one effective approach; these can include decals, patterned films, or DIY solutions like tempera paint or soap. For maximum effectiveness, these markings need to be spaced closely, typically no more than two to four inches apart, to ensure birds perceive the window as a solid barrier.
Installing external screens or netting a few inches away from the window surface can provide a physical barrier, cushioning any impact. Internal window treatments, such as closing blinds or curtains, or using external awnings, can also help by reducing reflections and the transparency effect of the glass. Adjusting the placement of bird feeders is another useful measure; positioning them either very close (within three feet) or far away (more than 30 feet) from windows can minimize high-speed impacts. During periods of increased activity, like breeding season, temporary solutions such as hanging streamers or covering windows with newspaper can deter persistent birds.
What to Do After a Collision
If a bird strikes a window, immediate and gentle action can help. First, observe the bird from a distance to assess its condition for signs of injury, such as a dazed appearance, bleeding, or an inability to fly. If the bird appears stunned but otherwise unharmed, approach it cautiously. Gently pick up the bird using gloves or a towel to minimize stress.
Place the bird in a small, well-ventilated cardboard box or paper bag, ensuring it has enough space to sit comfortably. Keep the container in a dark, quiet, and warm location, away from pets and children, allowing the bird time to recover from shock, typically for an hour or two. After this period, take the container to a safe, open outdoor area and release the bird. If the bird does not fly away or appears severely injured, contact a local wildlife rehabilitator or veterinarian. Avoid attempting to feed the bird or give it water, as this can cause further harm.