The only population of rare blue ducks outside New Zealand appears to be doomed.
Ben, a male put into a pen with Cherry, the last remaining female at a British sanctuary, has ignored her and instead bonded with Jerry, a male and the only other blue duck left outside New Zealand.
Both Ben and Jerry have shunned Cherry - ''who now swims sadly by herself at the other side of their pond'', London's Mirror newspaper reported.
Blue ducks are known as whio in New Zealand, and usually mate for life in the wild, and only a few thousand are left in the mountain torrents where they live.
A former Wildlife Service worker, Murray Williams, told NZPA that Britain's Wildfowl and Wetlands Trust (WWT) acquired blue ducks in the 1950s, and kept them at its Slimbridge sanctuary, but the last of them died in 1970.
The birds now in Britain are the survivors of birds which hatched from eggs taken there from New Zealand in 1985 by a researcher who ''talked his way past the boss of the Wildlife Service at the time,'' said Mr Williams, who now lectures at Wellington's Victoria University, on ecosystem restoration.
''They were to replace the ones that Sir Peter Scott snaffled here in the 1950s,'' he said. Sir Peter, the naturalist son of the polar explorer Robert Falcon Scott, visited New Zealand after setting up the WWT chain of wetland sanctuaries.
The 1985 batch of eggs was taken to the trust's Arundel sanctuary, in West Sussex, where the three survivors still live.
'' I'm surprised they're still alive,'' said Mr Williams.
He said that two pairs of birds did actually hatch some eggs, but the breeding efforts petered out, despite an unsuccessful attempt at artificial insemination over three years from 2000.
''It's got to the point of laughter really - they're old and nothing is going to happen,'' Mr Williams said.
They had never been intended as a backdoor breeding programme for New Zealand - biosecurity rules would have made it difficult to get birds back in to the country, and their genetic base was too narrow to be useful.
A trust spokeswoman at Arundel, Grace Rawnsley, said Jerry had shared the water at Arundel, West Sussex, with Cherry for years - but had shown no signs of interest in her.
So the trust brought in Ben, moved Jerry next door and waited to see what would happen. When love failed to bloom they re-introduced Jerry and suddenly everything went swimmingly... but only between the drakes.
''The fact they have turned out to be gay has played havoc with our breeding plans,'' she said.
Arundel Wetland Centre warden Paul Stevens told the Telegraph newspaper that the two male birds made ''a lovely couple''.
''They stay together all the time, parading up and down their enclosure and whistling to each other as a male might do with a female he wants to mate with,'' he said.
"It would have been nice to get a last clutch of eggs from Cherry but Ben and Jerry do make a lovely couple.''
