While urban parks are safe havens for birds, parks are often surrounded by condos and hotels and office buildings with floor-to-ceiling windows. And these all-glass building facades are the absolute worst for migrating birds. Because unlike people, birds don’t really understand glass.

It’s believed that building collisions are one of the biggest causes of bird death. Birds crash into buildings during the day because they don’t see the glass, and they run into buildings at night because they are lured in by artificial lighting. Most of these collisions happen below 100 feet, because that’s where birds are used to landing in trees.

Murder Most Fowl