http://www.nytimes.com/2011/01/18/science/18birds.html?hp

“Five billion birds die in the U.S. every year,” said Melanie Driscoll, a
biologist and director of bird conservation for the Gulf of Mexico and
Mississippi Flyway for the National Audubon Society.

That means that on average, 13.7 million birds die in this country every day.
This number, while large, needs to be put into context. The federal
Fish and Wildlife Service estimates that a minimum of 10 billion birds breed
in the United States every year and that as many as 20 billion may be in the
country during the fall migratory season.