American bald eagle
© Bruce Bennett/Getty Images
An American bald eagle sits on a branch at Mill Pond on July 21, 2018 in Centerport, New York.

The population of bald eagles in the lower 48 states of the US has quadrupled to more than 316,000 federal wildlife officials say.

The population was once on the verge of extinction but a new survey by the US Fish and Wildlife Service found more than 70,000 breeding pairs of the iconic bird.

Experts say that in the late 1960s there were less than 500.

The success of the raptor, which is the national symbol of the United States, is a "historic conservation success story," said newly confirmed Interior Secretary Deb Haaland.

"The bald eagle has always been considered a sacred species to American Indian people, and similarly it's sacred to our nation as America's national symbol," said Ms Haaland, the first Native American Cabinet secretary.

Bald Eagles were once hunted and poisoned across the US until they were included on the Endangered Species list in 1973 and given federal protection.

Their numbers have bounced back since that point and the bald eagle was removed forth list in 2007, and its numbers have quadrupled since the last survey in 2009.

Experts say that despite this success story the population of American birds has dropped by one-third in the last 50 years.