The Audubon Society has published a worrying study about the decline among America's most common birds. According to their findings based on a 40-years analysis, since 1967 the average population of the common birds in steepest decline has fallen by 68 percent; some individual species nose-dived as much as 80 percent.

“These are not rare or exotic birds we’re talking about—these are the birds that visit our feeders and congregate at nearby lakes and seashores and yet they are disappearing day by day,” said Audubon Chairperson and former Environmental Protection Agency administrator, Carol Browner

Twenty common birds - including the northern bobwhite, the field sparrow and the boreal chickadee - have lost more than half their populations in the past 40 years, according to the society's research.

Meadowlarks and other farmland birds declined because of suburban sprawl, industrial development and the intensification of farming, the society said.

"These populations are not yet on the endangered species list, but it is noteworthy, and we need to take steps to protect their habitat," added Carol Browner.

To read the entire report,  Audubon’s Common Birds in Decline, click here.