The bald eagle, the national symbol of the United States, has bounced back from near-extinction and numbers have quadrupled in the country since 2009, according to a new study.

The eagle's population crashed to an all-time low of 417 known nesting pairs in 1963 - not counting Alaska and Hawaii - but has since soared to more than 71,400 nesting pairs, the US Fish and Wildlife Service said.

Decades of protection efforts including banning of DDT pesticides have resulted in the bird flourishing, with the latest survey confirming a rapid, long-term growth of numbers.

"The recovery of the bald eagle is one of the most well-known conservation success stories of all time," said Service Principal Deputy Director Martha Williams.

She credited work between official agencies, tribes, non-government organisations and private landowners for the successful recovery.

Secretary of the Interior Deb Haaland hailed the "historic conservation success story," saying "announcements like ours today give me hope."