Bird–window collisions

Bird–window collisions (also known as bird strikes after the aviation term or as window strikes) are a problem in both low- and high-density areas worldwide. Birds strike glass because reflective or transparent glass is often invisible to them. It is estimated that between 100 million and 1 billion birds are killed by collisions in the United States annually, and an estimated 16 to 42 million birds are likewise killed each year in Canada.