Each year, hundreds of millions of birds die due to collisions with windows, a stark reminder of human impact on wildlife. Birds of all kinds, flying at considerable speeds, often find window impacts fatal. Even those that initially survive are frequently left stunned and vulnerable, falling prey to predators like domestic cats shortly after.
Understanding Bird Window Collisions
The core reason birds fly into windows is deceptively simple: they don’t perceive glass as a solid barrier. Instead, they see reflections of the sky, trees, and surrounding greenery, mistaking these reflections for open flyways. This is particularly true for windows reflecting natural habitats, creating an illusion of continuous landscape.
Migration patterns also play a significant role. Many bird species migrate at night, using stars for navigation. Urban lights can disorient them, drawing them into cities along their migratory routes. Light pollution becomes especially problematic on foggy or stormy nights when city outlines and light sources are obscured. This disorientation can lead birds to land in urban environments, collide with buildings, and in extreme cases, succumb to exhaustion. When these grounded birds attempt to take flight again in the morning, they often head directly towards reflections in windows, resulting in collisions.
Window strikes are not limited to large buildings or specific times of day. Research indicates that birds can hit windows of all sizes, from ground-level windows in houses to those in high-rise buildings, and at any time, day or night. Factors like the placement of bird feeders and birdbaths can also inadvertently increase the risk if they are located in areas that encourage birds to fly towards reflective windows.
Effective Strategies to Prevent Bird Window Strikes
Fortunately, there are several effective measures homeowners and building managers can take to significantly reduce bird window collisions.
Observe Collision Patterns
Often, window strikes are not random events but follow recognizable patterns. You might notice dead or injured birds repeatedly beneath the same window, possibly at specific times of the day. To understand what the birds are seeing, stand directly in front of the glass. Observe the reflection, paying attention to how it changes under different lighting conditions throughout the day.
If you have bird feeders or birdbaths, monitor whether birds are colliding with windows after taking flight from these locations. If collisions are occurring, a widely accepted recommendation is to move feeders closer to the window. Birds launching from feeders only 2 or 3 feet away from a window rarely achieve enough speed to cause serious injury upon impact.
Provide an Impact-Absorbing Barrier
Simple window screens are surprisingly effective in preventing window strikes. They not only disrupt reflections but also provide a cushioned, impact-absorbing surface for birds that might fly towards the window.
Consider installing screens on windows, securing them with hooks or suction cups. This reduces reflection and softens any potential impact, minimizing injury to birds. Furthermore, screens can deter territorial birds from attacking their own reflections in the glass, a behavior sometimes mistaken for window collisions.
Break Up Reflections
Decals and stickers are another useful tool. To be effective, they should be at least 6 inches in diameter and applied to the exterior of the window. Space them no more than one foot apart, both horizontally and vertically, to create a visual signal that birds can recognize as an obstacle.
For a less visually intrusive option, consider ultraviolet (UV) decals. These decals are nearly invisible to the human eye but contain components that reflect ultraviolet sunlight, creating a bright, glowing pattern that is highly visible to birds. While slightly more expensive, they offer a less disruptive alternative to traditional, opaque decals.
Outdoor string curtains offer another excellent solution. Commercially available options like Acopian Bird Savers are popular, but you can also create your own DIY versions. These hanging strands effectively disrupt reflections and create a safer environment for birds.
Helping Birds Injured from Window Collisions
When a bird strikes a window, it may suffer temporary incapacitation due to brain swelling. If you find an injured bird, the first priority is to protect it from immediate dangers, particularly cats or other predators. Gently place the bird in a covered box or under a ventilated container like a colander to ensure its safety.
Minimize handling the bird and resist the urge to offer food or water. As the swelling decreases and the bird becomes more active, it may be ready for release. Choose a safe, sheltered outdoor location, away from immediate hazards. If the bird does not recover within a reasonable time or appears to have sustained more serious injuries, it’s essential to seek assistance from a local wildlife rehabilitation center or veterinarian experienced with birds.
By understanding why birds fly into windows and implementing preventative measures, we can significantly reduce bird window collisions and contribute to the safety and conservation of these vital creatures.
