This video from the Cornell Lab of Ornithology in the USA says about itself:
Bird Mortality From Collisions With Glass: What we’ve learned, what we need to know, what you can do
1 May 2017
Over half a billion birds are killed every year in North America after colliding with windows. Birds can’t see glass-nor do they come to understand that it is an invisible barrier or reflective illusion-which means they don’t put on the brakes and usually hit windows at full force. In the last decade, many scientists have contributed pieces to the puzzle of how birds really see the world. This has established a basis for developing new solutions for existing glass, as well as materials and design strategies for creating new, bird-friendly buildings. Dr. Christine Sheppard discusses the tools we have to solve the birds and windows problem, and how we can get solutions implemented. This is one conservation issue where individuals can take immediate action and see immediate results.