Up to one billion birds die annually from window strikes in North America alone. Simple modifications to windows can save millions of bird lives every year.
Birds that strike windows and survive often die hours or days later from internal hemorrhage or concussion. The suffering of billions of birds annually makes this one of the largest preventable sources of bird mortality from human infrastructure. Glass that appears transparent to humans shows sky and vegetation reflections to birds, making them fly toward apparent open space. Even partial measures like window bird feeders placed very close to glass dramatically reduce fatal strike forces.