The world’s oldest known wild bird, a 74-year-old Laysan albatross named Wisdom, is expected to welcome another baby chick in the coming months, astonishing scientists who have been tracking her since the Eisenhower administration.

Wisdom laid an egg on November 27 on Midway Atoll, a speck of land in the Pacific Ocean, the US Fish and Wildlife Service said. Researchers said they were optimistic that it would hatch in about two months, making her a mother for the 30th or so time. Her last chick hatched in 2021.

Scientists have long marvelled over Wisdom’s longevity and her ability to breed as she gets older.

Jonathan Plissner, a supervisory wildlife biologist at Midway Atoll National Wildlife Refuge, told BBC Radio 4 on Wednesday that “it’s very rare” for a bird of Wisdom’s age to lay an egg, noting that “the average age that birds can survive is probably closer to 30 years”. The next oldest albatross that researchers are aware of at Midway Atoll is about 45 years old, he said.

“She is unique,” Plissner said. “We don’t know of any others that are even close to her age.”

Researchers at the wildlife refuge found that Wisdom had returned on November 26 to Midway Atoll, about 1,930km northwest of Honolulu — and the site of one of the biggest battles of World War II, just a few years before she was born.

Wisdom immediately began interacting with a new mate upon her arrival, the scientists said.

While albatrosses usually mate for life, they will find new mates to breed with if their partner dies. Plissner believes Wisdom has outlived at least three mates.

She hatched and raised chicks with another albatross named Akeakamai for decades, most recently in 2021, but Akeakamai has not been seen in several years. Wisdom’s new mate was outfitted with a tracking band last Friday. He stayed back to incubate the egg while Wisdom headed back to sea for a time, researchers said.

Carl Safina, a marine ecologist at Stony Brook University who has studied seabirds, said that Wisdom is aptly named because of her ability to survive despite increasing environmental dangers to albatrosses, including plastic pollution and rising sea levels that threaten their nesting grounds.

Birds can lay eggs late into life, although they may slow down as they get older, Safina said. Albatrosses can lay only one egg a year, and Wisdom has laid about 50 to 60 eggs since researchers began tracking her in 1956, the Fish and Wildlife Service said on Tuesday. At least 30 chicks have hatched from those eggs and flown from the nest, Plissner said in the agency’s statement.

“I think it’s impossible for us to look at that bird and not be stunned that she is still breeding and has laid an egg,” Safina said.