Mood Music for Ibises

Waldrapp ibises are extremely rare—only about 400 of the birds exist in the wild. So the zoo’s birds had a job to do. Yet they showed little interest in mating.

“They had pretty much stopped courtship behavior. They were just going through the motions,” said zoo ornithologist Mark Hofling, who leads the AZA Species Survival Program (SSP) for Waldrapp ibises in North America.

Zookeepers realized that if the Waldrapps were going to help their species survive, they were going to need more encouragement.

That’s where the mood music comes in.

The zoo’s bird department turned to Alan Clark, a biology professor at Fordham University, who began recording ibis mating calls at WCS’s Bronx Zoo and the Philadelphia Zoo. Clark realized he needed more, so this spring, he recorded the calls of a semi-wild population of Waldrapp ibises in Austria.

Clark brought those European “love songs” back to the Bronx Zoo, and keepers set them up for the flock using an iPod, a set of speakers, and a looping playlist. The birds snapped to attention.

In May, six baby ibises hatched. Within six weeks, the chicks had grown to an adult weight of around two pounds.

“If it works with this one species, there’s the possibility we can apply it to a wider range,” said Nancy Clum, the zoo’s curator of birds. The zoo’s next album du amor will be for Caribbean and Chilean flamingoes.

Before habitat loss and pesticide use began taking their toll on Waldrapp ibis numbers, the birds lived in large colonies that nested on the sides of cliffs throughout the Mediterranean region. Presently, the birds only breed in the wild in Morocco and in Syria.