Six endangered Waldrapp Ibis chicks like the one above (l.) were born at the Bronx Zoo several weeks ago. The birds mated after a soundtrack of mating calls was piped into their enclosure. Watts for News
A low-libido colony of endangered birds in the Bronx got their groove back - thanks to love songs piped into its home.
The flock of 21 Waldrapp ibis living at the Wildlife Conservation Society's Bronx Zoo had produced no chicks for seven years.
After zookeepers piped in a sexy soundtrack of mating calls recorded halfway around the world, they turned frisky and have hatched six offspring from three sets of parents.
It's a coup because the birds are extremely endangered - there are just 400 left in the wild - and rarely reproduce in captivity.
"The whole species is at risk," said Mark Hofling, a zoo ornithologist who oversees the species survival plan for ibis in North America.
"They had pretty much stopped courtship behavior," Hofling said of the Bronx birds. "They were just going through the motions."
Two years ago, Dr. Alan Clark of Fordham University recorded the flock's own mating calls, hoping to create aural Viagra by playing them on an endless loop.
There was too much outdoor ambient noise on the tape, so Clark tried again last year at the Philadelphia Zoo's indoor display.
The recordings, played back in the Bronx last spring, did seem to get them in the mood, but they still produced no chicks.
So this spring, Clark upped the ante and visited a semiwild flock in Austria, returning with the perfect recordings of the birds' three distinct mating calls: a chirrup, a whoop whoop and a shrum shrum.
When they found the right sounds, they were played mornings and afternoons from an iPod hooked to speakers on the ibis' wire mesh enclosure near JungleWorld.
And the birds got busy.
They built nests, preened and necked. Several couples laid eggs, and the six chicks hatched in May. The birds grew to adult size, about 2 pounds, in six weeks.
Now zoo officials are trying the same technique on Caribbean and Chilean flamingos, also experiencing a dry spell.
"If it works with this one species, there's the possibility we can apply it to a wide range," said Dr. Nancy Clum, chief ornithologist at the zoo.
It took some experimenting to isolate the right flamingo calls.
"It can sound like a lot of noise," Clum said of the recordings. "You don't want to be playing a vocalization to them that's actually an alarm call."
Meanwhile, the zoo is installing a professional sound system for the ibis for next spring's mating season.
The adult fowl have pink featherless heads splotched with black spots. They can live into their 30s.
"They have beautiful glossy plumage," Hofling said. "People come and say, 'Oh, that's an ugly bird.' I tend to disagree. They're unique."
The mating success doesn't mean the ibis are on the road to repopulation.
"The reasons that made them endangered - human encroachment, pesticide use - are still with us," Hofling said.