Toads Closer to Tanzanian Home

The Kihansi spray toad (Nectophrynoides asperginis) is a fairly new species to science, discovered only in 1996. There were once as many as 21,000 of the toads living in a five-acre region around Kihansi Falls in the Udzungwa Mountains of eastern Tanzania. They could be found nowhere else in the world and are particularly special because the females give birth to fully formed baby toads, bypassing the tadpole stage.

About a decade ago, a dam built upstream cut off 90 percent of the flow of water to the region. Artificial sprinklers were set up to mimic the natural spray of the falls, but they were unreliable. This may have made the toads more susceptible to the chytrid fungus, which was detected in dead Kihansi spray toads in 2003. The sprinklers failed that year and a brief opening of the dam's floodgates released water tainted with pesticides at high enough levels to potentially kill the toads. The Kihansi spray toad population crashed. In January 2004, just three toads could be found, and none have been seen since an unconfirmed sighting in 2005. The IUCN now lists the species as Extinct in the Wild.

Two populations of the toads now live in zoos: 5,000 at the Toledo Zoo and 1,500 at the Bronx Zoo. A third population was established just this week at a facility in Dar Es Salaam, Tanzania, as part of a program established by the two U.S. zoos, the Tanzanian government and the World Bank. One hundred toads were transferred to the Tanzanian facility in the hopes that they soon may be reintroduced to their previous home territory.

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Sarah Zielinski | | READ MORE

Sarah Zielinski is an award-winning science writer and editor. She is a contributing writer in science for Smithsonian.com and blogs at Wild Things, which appears on Science News.