An extremely rare Hawaiian bird has died in captivity, possibly marking the extinction of its species only 31 years after it was first discovered.
Many bird species are in decline due to habitat loss and introduced predators
The Po'o-uli, which was suffering from avian malaria, belonged to one of the world's most threatened bird families - the Hawaiian honeycreepers.
Thirteen other honeycreeper species have already died out, in what some are calling Hawaii's extinction crisis.
Many species are in decline due to habitat loss and introduced predators.
"The tragic death of this bird means that we may now be too late to prevent the addition of the Po'o-uli to the depressingly long list of recent extinctions in Hawaii, " said Stuart Butchart, of BirdLife International.
"It should serve as a wake-up call to redouble our efforts to save Hawaii's threatened species."
The small, stocky, brown Po'o-uli (Malamprosops phaeosoma) was first discovered in 1973, in Maui's Ko'olau Forest Reserve. Even then it was desperately endangered, with an estimated population of fewer than 200 individuals.
Since then, its decline has been steep. In 1995, fewer than seven birds were known and by 1997 that number had dropped to just three individuals.
However, none of these three remaining Po'o-uli seemed keen to breed, and each maintained a distinct home range in Hanawi Natural Area Reserve and the immediately adjacent Haleakala National Park.
In 2002, one of the three individuals was caught and placed in the range of another, in an attempt to get them to mate. But the plan failed and the introduced bird soon left the area.
The following year conservationists decided to take drastic action and capture all three birds to begin a captive breeding programme.
But this proved difficult, and only one bird was caught in September 2004, which is the individual that has just died.
On Tuesday a hunt began for the two remaining birds - believed to be a male and a female - but they have not been seen for nearly a year and hopes for their survival are slim.
"This species was a unique part of Earth's history," said Eric VanderWerf, of the US Fish and Wildlife Service. "We'll never have another one like it if it disappears.
"I kind of liken it in some way to the loss of the Mona Lisa or the Sistine Chapel. If we lost that we could never get it back."
Tissue samples from the dead bird were saved for possible cloning in the future; it could be the species' only hope.
As well as habitat loss, Hawaii's massive bird losses are blamed on introduced mosquitoes, which carry diseases like avian malaria.
On top of the Po'o-uli, a further seven species of Hawaiian honeycreeper are classified as Critically Endangered, with another endemic land bird, the Hawaiian Crow, now considered to be Extinct in the Wild.
"Hawaii's bird extinction crisis is a global tragedy that is largely being ignored," said George Fenwick, President of American Bird Conservancy.
"That the world's wealthiest nation is allowing bird extinctions to continue, largely unchecked, is unconscionable."