Zoo joins in effort to save rare toads

Species is found only in a 10-acre spot in southern Tanzania

April 22, 2001|By Martin Mbugua | Martin Mbugua,KNIGHT RIDDER/TRIBUNE

NEW YORK - They're the color of a lime, not much bigger than a dime and have a new home at the Bronx Zoo in a race against time.

"They" are the zoo's newest - and certainly one of its tiniest - denizens: Kihansi spray toads.

Trying to save the toad - a rare species found only in a 10-acre spot in southern Tanzania - from extinction, the zoo's World of Reptiles has taken in 250 of them.

Mossy home ruined

Slightly smaller than a quarter when fully grown, the toads were discovered in 1996 during an environmental impact study for a World Bank-funded power generation dam in Tanzania's Kihansi Gorge.

The dam eventually reduced the water supply and ruined the toads' soggy, mossy home, said Jason Searle, a herpetologist who brought 500 toads to the United States in November. Half went to the Detroit Zoo.

"Part of the recommendation was to bring a population into captivity," he said. "We hope to maintain a viable population so that in the future we will be able to reintroduce a genetically healthy population."

Searle said scientists are particularly interested in learning about the amphibian's "extremely rare" reproductive method - eggs are fertilized inside the female even though toads have no reproductive organs, and their offspring are born fully formed.

Since their arrival, the toads have given birth to more than 200 toadlets.

Parasite trouble

But more than 100 adults have succumbed to a parasitic worm one-third their size in their stomachs.

Searle said the remaining adults and their offspring will stay out of public view until the worm is eliminated and more is learned about the toad.

Zoo staff clean the toads' plastic containers several times a week, keep an eye on temperature and mist levels, and feed small crickets to the adults and microscopic insects to the toadlets.

The toads' plight has caught the attention of conservationists and the Tanzanian government. The World Bank has approved an alteration to the project that would direct water toward the toads' home and has started discussing a $5 million loan to maintain the habitat around the dam.

But Searle said time is running out.

"When I was there in November, 99 percent of the habitat was gone," he said. "Almost all of the original vegetation is gone. The ... latest [toad population] estimate is between 1,500 and 2,000."

The Kihansi hydropower project in the Udzungwa mountains of southern Tanzania was completed last April and consists of three 60- megawatt generators with the capacity to generate a total of 180 megawatts.

The project is vital to Tanzania because mining and tourism investments have pushed demand for power to more 550 megawatts, but maximum output for the nation is 416 megawatts.

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