Birds frequently collide with windows, a common and distressing event. This widespread problem contributes to significant avian fatalities annually. Understanding the reasons for these collisions is the first step toward mitigation. This article explores why birds strike windows, offers prevention strategies, and outlines actions to take if a collision occurs.
Understanding Why Birds Collide
Birds often strike windows because they cannot perceive glass as a solid barrier. Instead, windows frequently act as mirrors, reflecting the surrounding environment such as trees, sky, or clouds, leading birds to believe they are flying into open space or continuous habitat. This reflection confusion is a primary cause of collisions, particularly during daylight hours when birds are actively foraging or seeking shelter.
In other instances, birds may attempt to fly through transparent glass, mistaking it for an unobstructed path. They might see vegetation or an exit point on the opposite side, failing to recognize the clear pane as an obstacle.
Certain male birds, especially during breeding season, attack their own reflection, perceiving it as a rival. This behavior can be exhausting. Birds possess excellent visual acuity and can perceive ultraviolet light, but they lack the ability to understand their own reflection or to see in 3D, contributing to this misperception.
Artificial lighting also plays a role, particularly at night during migration periods. Birds often navigate using natural celestial cues, and artificial lights can disorient them, drawing them off course towards urban areas and structures. Once drawn in, they become more vulnerable to collisions with illuminated buildings.
Additionally, birds might be drawn to indoor elements visible through a window, such as houseplants or food sources, attempting to reach them. Lastly, birds fleeing from predators may fly erratically and at high speeds, making it difficult for them to perceive glass as an obstruction.
Effective Prevention Strategies
Making windows visible to birds is a primary prevention method. Applying decals, tapes, or films to the exterior glass can break up reflections and transparency, signaling an obstruction. Products like Feather Friendly tape, which creates a grid of small squares, make the window apparent to birds. Markers should be spaced closely, no more than two to four inches apart, to be effective for various bird sizes.
External screens provide a physical barrier that absorbs impact and eliminates reflections. Adjusting bird feeder placement also reduces collision risk; place feeders either very close (within three feet) or far away (more than 30 feet) from windows. When feeders are very close, birds cannot gain sufficient speed to cause serious injury. Moving indoor plants away from windows can prevent birds from attempting to fly through the glass.
Modifying lighting, especially during peak migration seasons (roughly March 1 to June 15 and August 15 to November 30), significantly aids nocturnal migrants. Turning off non-essential interior and exterior lights from 11:00 p.m. to 6:00 a.m. can reduce disorientation and attraction to buildings. Simple DIY solutions, such as hanging strings or ribbons no more than four inches apart across the outside of the window, can also create a visual deterrent.
Responding to a Window Strike
If a bird strikes your window, the immediate action involves observing the bird from a distance to assess its condition. If the bird appears stunned but otherwise uninjured, it may recover within a few minutes to a couple of hours. It is advisable to secure any pets and ensure the area around the bird is quiet and safe from predators.
Should the bird remain stunned or unable to fly after a short period, gently contain it by placing it in a small, dark, well-ventilated cardboard box or paper bag lined with a soft cloth. The darkness and quiet environment can help calm the bird and reduce stress, aiding its recovery. Do not attempt to give the bird food or water, as this can cause further harm.
If the bird shows signs of visible injury, such as bleeding, a drooping wing, inability to stand, or prolonged disorientation, it requires professional assistance. Contact a local wildlife rehabilitator; they possess the expertise to treat internal injuries and provide appropriate care. Handle a bird with care to prevent injury to both yourself and the bird. Many birds that appear to recover and fly away may still suffer from internal injuries, such as concussions or internal bleeding, which can lead to delayed mortality.