Updated Wednesday, February 6, 2013 at 06:35 AM
The world’s oldest known living wild bird at age 62 gave birth to a healthy chick that hatched Sunday, challenging the conventional wisdom about how long birds remain fertile.
This bird, named Wisdom by scientists who stuck a tag on her ankle years ago, has lived longer than the average Laysan albatross, which dies at less than half her age. Scientists thought that, like other birds, albatross females became infertile late in life and carried on without producing chicks.
Wisdom, which hatched the chick at the Midway Atoll National Wildlife Refuge in the Pacific Ocean, has raised chicks five times since 2006, and as many as 35 in her lifetime.
Just as astonishing, she has likely flown as many as 3 million miles since she was first tagged at the Midway Atoll at the end of the Hawaiian Island chain in 1956, according to scientists who have tracked her at the U.S. Geological Survey (USGS).
“It blows us away that this is a 62-year-old bird and she keeps laying eggs and raising chicks,” said Bruce Peterjohn, chief of the Bird Banding Laboratory at the USGS Patuxent Wildlife Research Center in Laurel.
“We know that birds will eventually stop reproducing, when they’re too old to breed anymore,” he said. “The assumption about albatross is it will happen to them, too. But we don’t know where that line is. That in and of itself is pretty amazing.”
Wisdom’s advanced-age delivery not only could help scientists understand more about the albatross, but also more about the health of the oceans.
Thousands of Laysan and other species of albatross have been banded since 1956, when scientists started studying them at the atoll to determine why so many were striking Navy aircraft, killing the birds and damaging the machines.
The tracking bands, also called tags, weren’t all that reliable. They generally fall off after 20 years, sometimes before being replaced. Wisdom went through six, which were replaced before she lost them.
As far as Peterjohn and other scientists know, “half the birds could be 60 years old,” he said. “These birds could be much older than we think.”
Nineteen of 21 albatross species are threatened with extinction, and their demise might be linked directly to humans. Long-line fishing has depleted their numbers. Fishermen throw bait in the ocean to lure fish, but they also lure albatrosses that get hooked and drown.
The birds also swallow marine debris. An estimated five tons of plastic are unknowingly fed to albatross chicks each year by their parents, the USGS said.
This might not kill the chicks quickly, but it restricts their food intake, leading to dehydration. Also, the birds are threatened by invasive species, such as rats and wild cats.
Albatrosses aren’t the world’s largest birds, or the oldest — parrots in captivity have lived to age 80, Peterjohn said. But they are stunning, and easily the largest sea bird, with wingspans as wide as eight feet, “like a sea gull on steroids,” Peterjohn said.
They’re the oldest-known bird in the wild. Wisdom edged out the second-oldest-known albatross to give birth, a 61-year-old named Grandma, of the Northern Royal species, Peterjohn said. But Grandma hasn’t been seen at her nesting ground at Taiaroa Head, New Zealand, in three years and is presumed dead.
Albatrosses mate for life, suggesting that Wisdom probably had to find a new, younger mate maybe twice down the line. They work at a relationship, first by getting their groove on. “They dance together,” said Chandler Robbins, a retired senior scientist at USGS.
Robbins was in his 40s when he clasped that first aluminum band around Wisdom’s ankle in 1956.
Still working at age 81, he returned to the atoll in 2001 and, amid the thousands of albatrosses that nest there, picked up a bird with a tag that traced back to one with a signature he recognized — his own. Scientists gave Wisdom her name and estimating her age at 49.