New York - A rare female pheasant at the Bronx zoo here has decreed two suitors too foul for mating - although being okay for casual dating.

"She spends time with the males," said ever-hopeful assistant curator for ornithology John Rowden on Tuesday, of the Bulwer's wattled pheasant. But "we haven't seen her mate yet".

Not for many years, anyway. The unnamed female laid and hatched eggs back in 1986, but for whatever mysterious reason, she's been spurning the mating call since then.

She's 16 - clearly no spring chicken, since pheasants of this species are believed to live only into their 20s. The fellows are nine and 17, and she mothered chicks with the older male back in the 80s.

"They had the magic and they lost it," said Rowden.

The dilemma has led to extraordinary efforts to reproduce their natural habitat - the rainforests of Borneo, a south-east Asian island - in the Bronx.

The trio live away from public scrutiny, in an aviary densely planted with bamboo under a canopy of leaves, "to give the female a chance".

The males perform a spectacular courtship dance, fanning their white tails and engorging their blue facial wattles with blood as they extend them for the female to admire. She can also hear their stiff quills rattling as they touch the ground.

The display is accompanied by loud vocalisation - taped by Rowden.

The two-note call is played at one-minute intervals in the morning and late afternoon, to create the illusion that there are many birds around.

"That gives the males the impression that they have to display vigorously, and the female that there are options, that the males are competing for her attention," said the ornithologist.

Rowden said: "I'm working pretty hard on this."

Alas, wattled pheasants rarely breed in captivity. Even in Borneo, "they're pretty rare", said Rowden, noting that the species was declining because of rainforest logging.

The San Antonio zoo has a mother-and-son pair, and there are three males in San Diego, in addition to some in captivity in Asia and Europe. "We've talked about trying to bring them together," said Rowden.

First, though, experts must figure out exactly what might be missing in captivity, including possibly lots of rain and a protein-rich diet.

The fact is, the brown female's feathers have yet to be ruffled by the black-and-blue males' mating programme.

Rowden said: "Here are two great males to partake of, and so far, it hasn't had the ultimate effect we're striving for." - Sapa-AP