Extinct in the Wild, Kihansi Spray Toad on Exhibit at Wildlife Conservation Society’s Bronx Zoo

New Exhibit Highlights the Work of WCS to Conserve a Species Extinct in the Wild

Bronx, NY – February 2, 2010 – The Wildlife Conservation Society’s Bronx Zoo announced today the opening of a new exhibit featuring the Kihansi spray toad, a species listed as extinct in the wild last year by the International Union for Conservation of Nature (IUCN).

The small, yellowish toad once occurred in large numbers but was only found in a verdant, moist five-acre microhabitat in the Kihansi gorge of Tanzania.  This species is unusual among toads; females give birth to live, fully-formed young, rather than laying eggs that hatch into free-living tadpoles. 

“The Wildlife Conservation Society is taking a leading role to ensure this toad does not disappear from the planet by playing an active role in its conservation,” said Jim Breheny, WCS Senior Vice President of Living Institutions and Director of the Bronx Zoo.

For the first time at WCS’s Bronx Zoo, visitors will be able to see and learn about the Kihansi spray toad. The exhibit is as unique as its inhabitants.  Keeping the toads comfortable necessitated the construction of a specialized system that filters, cools, and treats the water with ozone. The treated water is then delivered to the animals through a series of nozzles that create a fine mist within the enclosure. 

For nine years, a team of herpetologists at the WCS’s Bronx Zoo has been working behind the scenes on a conservation program intended to save the Kihansi spray toad from disappearing altogether by propagating the species for eventual reintroduction into its natural habitat.  

What happened to the Kihansi spray toad?

In 2000, the construction of a hydroelectric dam in the Kihansi Gorge of Tanzania was predicted to dramatically change the Kihansi spray toad’s habitat. The micro-habitat where the toad lived was dependent on the mist created by the waterfalls in the gorge. Although this dam is vital to the Tanzanian economy in that it generates one-third of Tanzania’s total electrical supply, its construction reduced the original size of the Kihansi falls to 10 percent of its former flow, drastically lessening the mist zone in which the toads thrived.

Following an agreement between WCS and the government of Tanzania, WCS scientists and Tanzanian officials collected an assurance colony of 499 Kihansi spray toads from the gorge.  The small colony was brought back to New York to initiate the off-site conservation program. 

Scientists are still debating the ultimate cause of extinction of this species in the wild, but it was probably a combination of habitat change and the emergence of infective chytrid fungus, which is responsible for alarming crashes and extinctions of amphibian species in many parts of the world.  The only remaining population of Kihansi spray toads consists of more than 4,000 individuals residing at WCS’s Bronx Zoo and the Toledo Zoo.

After being propagated at WCS’s Bronx Zoo for nine years, the project is entering the repatriation stage where WCS is working with the government of Tanzania and several international partners to return a small population to a facility at the University of Dar es Salaam within the next year.  The Tanzanian government has also been managing the Lower Kihansi Environment Management Project in the gorge.  A system of sprinklers, replicating the toad’s habitat, has been installed in preparation for the species’ return.  The ultimate goal of WCS and partners is to return the toads to the Kihansi gorge when habitat conditions can be assured for their long-term survival.