Two recent scientific studies estimate that more than 1 billion birds – and as many as 5.19 billion – die from collisions with sheet glass each year in the United States alone, sometimes immediately but often from their injuries.

In fact, window collisions are now considered the top human cause of bird deaths. Due to window collisions and other causes, bird populations across North America have declined more than 29% from their 1970 levels, likely with major consequences for the world’s ecosystems.