World's oldest wild bird gives birth
Image: David Wilibanks
At 62-years-old, an albatross named "Wisdom" is the world's oldest-known wild bird. She has astonished the wildlife community by recently giving birth to a healthy chick.
The average Laysan albatross dies at less than half Wisdom's age, and females are thought to become infertile late in life. Wisdom however, has raised chicks five times since 2006, and as many as 35 times during her life. She was tagged by scientists in 1956 at the Midway Atoll National Wildlife Refuge in the Pacific Ocean. Her unusual feat could prompt them to abandon some early theories about the albatross.
"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 Centre in Laurel. "We know that birds will eventually stop reproducing when they're too old. The assumption about albatrosses is it will happen to them too. But we don't know where that line is, " he added.
Prior to Wisdom's recent feat, the oldest-known albatross to give birth was a 61-year-old of the Northern Royal Species, says Peterjohn. He adds that due to shortcomings in the research, these birds could be even older, and in fact "half the birds [that were tagged] could be 60 years old." Tracking bands tend to fall off after 20 years, sometimes before they are able to be replaced, meaning the data may not be entirely reliable. Wisdom however, has been through six tags, with each one being replaced before the previous one fell off.
Chandler Robbins, a retired senior scientist at USGS was the first to tag Wisdom in 1956. Adding a remarkable twist to the story he returned to the atoll in 2001, then aged 81, and amid the thousands of birds that were nesting there, he picked up Wisdom, recognising her by his signature on the tag. Inspiring the excitement of scientists, who estimated her to be aged 49, it was then that she was given her name. Now aged 94, Robbins continues working, trying to address the tangled record keeping: "I'm trying to straighten out the record. It takes a lot."
Despite being the oldest-known wild birds, 19 of the 21 albatross species are threatened with extinction. Their numbers have been depleted by long-line fishing, as they are lured by the bait along with the fish, and become hooked and drown when they squat on the surface of the water to eat. Other threats to their survival include marine debris, which they unknowingly swallow, and invasive species such as wild cats which prey on their eggs and chicks.
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