However, these deaths represent just a fraction of the true impact humans have on birdlife.
"There are many human-related causes of bird mortality including buildings, outdoor cats, pesticides, communication towers, automobiles, wind farms, and lead poisoning from spent ammunition and lost fishing tackle." said American Bird Conservancy Vice President, Mike Parr. "But because most of the deaths from those sources often occur in ones or twos, they often go unnoticed or unreported."
In total, says Parr, studies have estimated that up to one billion birds may be killed annually due to collisions with buildings. Another billion fall prey to domestic cats. Up to 50 million birds are killed each year after hitting communications towers, and pesticide poisoning has been linked to the deaths of up to 15 million birds each year.
In addition to all these hazards, the increasing presence of wind turbines is a threat to many birds, especially when they're built in the path of migration routes.
"When you look at the totality of human-caused threats to birds, it has got to give cause for serious concern about our cumulative effects on their populations," Parr said.
Read more at mongabay