More than 30% of North America's bird populations are in "significant decline" according to conservationists.
The American Kestrel can hover like a hummingbird
The National Audubon Society's State of the Birds report draws on data collected between 1966 and 2003 for 654 American bird species.
The report looked at birds inhabiting grasslands, shrublands, forests, waterways and urban settings.
The report says the declines are abnormal and not part of the cyclical rise and fall in bird populations.
Most disturbing was the finding that 70% of bird species living in grasslands - such as the eastern meadowlark, bobolink, short-eared owl and greater prairie-chicken - are doing poorly.
The report found that for shrubland birds - including the northern bobwhite, painted bunting and Florida scrub-jay - 36% of species are declining significantly.
Smaller declines were noted in bird species living in forests, wetlands and urban areas.
Instead, they may be caused by the loss of native grasslands, overgrazing of grassland and shrubland, development of wetlands, bad forest management, invasive species, pollution and poor land use decisions.
DECLINES IN NORTH AMERICAN BIRDS
70% of grassland species declining significantly
36% of shrubland species declining significantly
25% of forest species declining significantly
13% of wetland species declining significantly
25% of urban birds declining significantly
"Like the canary in the coal mine warning the miner of danger ahead, birds are an indicator of environmental and human health," said Audubon president John Flicker.
"People created these problems and people can solve them if we act now."
The data contained in the report comes from the national Breeding Bird Survey counts from 1966 to 2003. The survey is coordinated and analysed by the US Geological Survey.
The report calls for more protection for the birds' habitats and increased conservation efforts by private landowners and homeowners.