The building that will save birds in Chicago

How many birds die every year after hitting the windows of tall buildings? Billions. In the US and Canada alone, what's known as "architectural glass" kills 34 million birds a year during their spring and autumn migrations. Because Chicago is the middle of a big migration route, city officials are making bird safety a priority.

When the Aqua Tower at Lakeshore East near Lake Michigan is finished, it will resemble cliffs more than a skyscraper. The architects, Studio Gang, say that the organically shaped balconies and a new type of glass visible to birds will save many little lives.

Birds generally do not see glass as a solid. But, unlike humans, they see ultraviolet light as a separate colour, so UV-reflective glass could help save bird lives. It is very expensive, though, and companies won't make bird-safe glass until there is a big market for it.

"There has to be a way to solve this problem," Jeanne Gang of Studio Gang told the Financial Times. She would like the US government to force skyscrapers to use bird-safe glass, but Glenn Phillips of the Audubon Society says, "Until we have an array of solutions to the problem, it's not viable to try to prohibit bird-unfriendly buildings."