Conservation efforts are helping stem dwindling numbers of some bird species, according to report based on 40 years of data analysed by official US agencies.
The report shows such efforts have protected 30 million acres of wetlands and contributed to thriving populations of hunted waterfowl, herons, egrets and other birds, according to the US State of the Birds report.
On the whole, 39 species of hunted waterfowl have increased by more than 100 percent during the past 40 years. Successful waterfowl conservation is a model for widespread habitat protection.
"By bringing together the data, the analytical expertise and the combined voices of government and non-governmental organisations, this... report brings new power to the essential message the birds are conveying,"said John Flicker, President, National Audubon (BirdLife in the USA) Society.
On the flip side, the report also reveals sobering declines of bird populations during the past 40 years - a warning signal of the failing health of ecosystems.
Threatened by habitat destruction, invasive species, and disease, nearly all native Hawaiian bird species are in danger of extinction if urgent conservation measures are not implemented immediately.
Since humans colonised the islands in 300 AD, 71 Hawaiian bird species have gone extinct; 10 others have not been seen in as long as 40 years.
At least 39 percent of US bird species restricted to ocean habitats are declining and almost half are of conservation concern, indicating deteriorating ocean conditions.
Management policies and sustainable fishing regulations are essential to ensure the health of oceans, said a US Geological Survey release.
Mr. Flicker concluded that "birds are sending us a wake-up call that the habitat destruction, climate change and shortsighted environmental policies of the past are combining to take a serious toll.