Nov. 7, 2005 — The world's oldest known female whooping crane has died of old age, Canadian wildlife officials announced last week, celebrating her long life as proof efforts to save the endangered species are working.

The 28-year-old bird was found dead on the edge of Muskiki Lake in the western Canadian province of Saskatchewan a month after she disappeared.

Wildlife officials had last seen her feeding with her mate and chick in a nearby field, said Brian Johns of Environment Canada's wildlife service.

"I suspected something was wrong. When I later received a sighting report of a single adult with a chick on the same lake I decided to investigate," he said.

Biologists, who had followed her since she was hatched in a remote area of Wood Buffalo National Park in 1977 as part of the longest and largest ever conservation effort to reestablish the species, found two piles of feathers and a carcass that had been dragged to a nearby bush.

"Twenty-eight is a ripe old age for a crane, so I suspect she died of old age and was then scavenged by a fox or coyote," Johns said of the bird, affectionately dubbed "Green-Red" for the colored bands biologists attached to her legs as a chick.

Whooping cranes are the largest birds in North America, measuring 1.5 meters (five feet) tall, with white plumage, black-tipped wings that stretch two meters (6.5 feet) from tip to tip and a red and black colored head.

The species reproduces slowly. Over the past three decades the population has grown by an average of four percent per year.

Green-Red's long life gave biologists hope the species could survive by having more offspring over a longer period of time and reaffirmed conservation measures such as establishing secure breeding grounds and a hunting ban, Johns told AFP.

Green-Red had 11 offspring with two different mates, helping to bring the species back from the brink of extinction.

"It's the oldest known female in the world. She gave us an idea of how long whooping cranes can live in the wild," he said. "And, she gave us hope."

In 1941, there were only 21 whooping cranes left in North America. There are now 475, including 130 in captivity.

Green-Red was part of a wild flock of 217 birds that migrate each year to the Aransas National Wildlife Refuge in Texas, covering an estimated 225,000 kilometers (140,000 miles) in her lifetime.

The average lifespan of a whooping crane is not yet known, Johns said, but most studied have lived 10 to 25 years. The oldest known male is now one year younger than Green-Red.