The sudden thud of a bird striking a window is a common and often distressing event for homeowners. This phenomenon, which can result in injury or death for the bird, occurs frequently. Understanding the reasons behind these collisions and knowing how to respond can help protect local bird populations.
Understanding Why Birds Hit Windows
Birds frequently collide with windows because glass can be invisible or misleading to them. They often perceive reflections in glass as a continuation of their natural habitat, such as open sky or surrounding trees. This visual illusion leads them to attempt to fly through what appears to be clear space, causing an impact.
The transparency of glass also contributes to collisions, especially when birds see through a window to plants or other attractive elements inside a building, or to an exit on the other side. They may mistakenly believe there is a clear flight path through the structure. This “fly-through” effect can also occur with glass railings or other structures where birds anticipate an unobstructed passage.
Beyond visual misinterpretations, other factors can increase the risk of collisions. Birds might become disoriented or startled by predators or loud noises, causing them to fly erratically into windows. During migration, particularly at night, artificial lights from buildings can attract and disorient birds, increasing their vulnerability to daytime collisions. Weather conditions like fog, low clouds, or strong winds can also amplify this disorientation, making it harder for birds to perceive glass barriers.
Some birds may also strike windows due to territorial behavior. They might see their own reflection in the glass and perceive it as a rival, leading them to attack the window. While this can cause bill injuries, it is generally less fatal than collisions from misinterpreting reflections or transparency.
Preventing Future Bird Collisions
Making windows visible to birds is the primary strategy for preventing collisions. Applying visual deterrents to the exterior surface of the glass can break up misleading reflections. These can include decals, tape strips, or patterns that are spaced closely together, typically no more than two to four inches apart, to ensure even smaller birds recognize the barrier. Products like Feather Friendly tape, which use small dots, have shown to be effective by making the glass visible to birds.
Exterior window screens are another effective solution, as they obscure reflections and provide a physical barrier. These screens can cushion an impact if a bird does hit, reducing the severity of potential injuries. Netting installed a few inches from the glass can also serve a similar purpose, allowing a bird to bounce off safely.
Adjustments to indoor and outdoor environments can also help. Closing blinds or curtains can reduce the transparency and reflections that attract birds. Relocating indoor plants away from windows can prevent birds from attempting to fly through the glass to reach perceived foliage.
Consider the placement of bird feeders and birdbaths; placing them either very close (within three feet) or far away (more than 30 feet) from windows can reduce collision risk. When feeders are very close, birds cannot build up enough speed for a fatal impact. Conversely, keeping them far away minimizes the chance of a bird being startled from the feeder and flying directly into a window.
Responding to a Window Collision
If a bird strikes your window, approach it cautiously to assess its condition. The bird may be stunned, injured, or deceased. If it appears stunned but otherwise uninjured, it may recover within a few minutes to an hour or two.
For a stunned bird, gently place it in a small, dark, and quiet container, such as a shoebox, with a lid and air holes. Line the bottom with a soft cloth, avoiding materials with loops that could entangle the bird’s feet. Place the box in a safe, warm location away from pets and human activity. Do not attempt to force-feed the bird or give it water, as this can cause aspiration.
Check on the bird periodically, but avoid excessive handling or interaction, which can increase stress. Once the bird appears alert and ready, take the box outside to a safe, open area, away from structures, and gently open the lid to allow it to fly away. If the bird does not recover and fly away within a few hours, or if it shows signs of obvious injury like a broken wing, bleeding, or unresponsiveness, it needs professional help.
Contact a local wildlife rehabilitator or animal control for guidance. These professionals are equipped to provide specialized care for injured wild birds. You can find a rehabilitator online. If the bird is deceased, it is generally recommended to bury it or leave it in place, and avoid direct contact.