The Kihansi Spray Toad, Nectophrynoides asperginis,is listed as ‘Extinct in the Wild’ on the IUCN Redlist of Threatened Species. It was only known from one locality: in the spray zone of the Kihansi Falls in the Kihansi Gorge, of the Udzungwa Mountains, of eastern Tanzania. Currently, an experimental reintroduction is being undertaken in the wild and the species breeds in captivity in the Toledo Zoo and Bronx Zoo.
The construction of a dam on the Kihansi River is the most likely cause of the Kihansi Spray Toad’s extinction. The dam cut off 90% of the water flow to the gorge, so an artificial sprinkler system was built to restore the spray zone wetlands. However, failures of this sprinkler system in 2003 combined with an outbreak of chytridiomycosis in the toads, or possibly other factors, were enough to cause serious decline and extinction.
Successful captive breeding at the Toledo Zoo in Toledo Ohio, the Bronx Zoo in New York City and at the University of Dar es Salaam in Tanzania lead to the reintroduction of 2,500 individuals in Tanzania in 2012. In the past, captive populations have fluctuated due to some infections and nutritional deficiencies, but those problems have since been addressed. Only with effective monitoring of the reintroduced animals will we be able to determine the ultimate success of the reintroduction of the species back to Kihansi Falls. A variety of factors, including the status of the habitat, the effectiveness and reliability of the sprinkler system, presence of diseases, and reproductive rate of the toads, and others, will determine long-term success.