Every year, between 365 million and one billion birds (11)  __________ thought to be killed in building collisions in the US. More than half of those crashes are actually with low-rise buildings, such as people's homes. Birds may collide with them in small numbers per building, but it adds up, as houses are so widespread. However, big lit-up buildings such as skyscrapers may kill hundreds of birds at once. (12) __________ October 2023, nearly 1000 birds (13) ___________ in a single night during their autumn migration from hitting a skyscraper in Chicago.

Many birds migrate by night, and use the (14) _________ to find their way. During their night migration, they are often seen gathering around or crashing into lit-up windows and structures. One explanation is that they may usually (15) ___________ towards light sources, but unfortunately, the artificial light confuses and traps them.

(Adapted from www.bbc.com)

Every year, between 365 million and one billion birds (11)  __________ thought to be killed in building collisions in the US