The only female blue duck outside New Zealand has been passed over by two males, who reportedly prefer each other's company.
Cherry, the last remaining female at a British sanctuary, has been ignored by Ben, who has instead bonded with Jerry, a male and the only other blue duck leftoutside New Zealand.
Both Ben and Jerry have shunned Cherry - "who now swims sadly by herself at the other side of their pond", the Sunday Mirror newspaper reported.
Blue ducks, or whio, usually mate for life in the wild, and only a few thousand are left in the mountain torrents where they live.
Grace Rawnsley, spokeswoman for the Wildfowl and Wetlands Trust at Arundel, West Sussex, said Jerry had shared the water with Cherry for years - but had shown no signs of interest in her.
So the trust brought in Ben and moved Jerry next door.
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 said the two male birds made "a lovely couple".
"They stay together all the time, parading up and down 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."
