Because birds don't have depth perception like humans do, and can confuse the reflections in buildings with more sky, many are killed after colliding with glass windows and curtain walls - to the tune of 100 million to one billion (!) every year in North America by one estimate.
In recognition of the increasing problem, ornithologists and architects are working to devise solutions such as special glass coatings and frits to break up reflections and make buildings more visible to birds.
Additionally, "Several cities in the U.S. and Canada either have or are considering new building codes that require bird-friendly materials. And there are some quick fixes for windows - decals or sheets of patterned plastic that attach to glass."
"But ideally," writes Joyce, "biologists and architects want solutions that people can't see and that will be standard products in buildings - and that won't cost an arm and a leg."
Thanks to Daniel Lippman