It’s a startling sound, the thud that occurs when a bird mistakes a window for clear flight space and strikes glass instead. Your heart sinks to think about the possible outcomes—at worst, the loss of life, at best, a temporarily stunned and disabled bird that could use all the help it can get until it recovers enough to enable flight.

With spring migration underway, chances for such collisions increase, as birds sometimes see the reflections of tree branches or landscapes with open sky in our glass windows. Night collisions also occur, when nocturnal migrants like thrushes and warblers are haplessly diverted from their migration paths by lighted windows, although it remains unclear why. 

There are a variety of strategies for making windows safer for birds, such as relocating feeders, or covering glass with screening or a one-way transparent film that makes windows appear opaque from the outside. Visit the Fatal Light Awareness Program’s (FLAP) website at flap.org to learn more. FLAP also maintains a global bird collision database where citizen scientists can report collisions near their homes to help determine the scope of this unfortunate problem.