Washington • North America’s skies are lonelier and quieter as nearly 3 billion fewer wild birds soar in the air than in 1970, a comprehensive study shows.
The new study focuses on the drop in sheer numbers of birds, not extinctions. The bird population in the United States and Canada was probably around 10.1 billion nearly half a century ago and has fallen 29% to about 7.2 billion birds, according to a study in Thursday's journal Science .
"People need to pay attention to the birds around them because they are slowly disappearing," said study lead author Kenneth Rosenberg, a Cornell University conservation scientist.