Kihansi Spray Toad
|Kihansi spray toad|
|Kihansi Spray Toad at the Toledo Zoo|
Poynton, Howell, Clarke & Lovett, 1999
The Kihansi spray toad, Nectophrynoides asperginis, is a yellowish dwarf toad, with females reaching up to 2.9 cm (1.1 in) long and males up to 1.9 cm (0.75 in). This ovoviviparous species was scientifically described in 1999.
It was found only in the spray zone around the Kihansi waterfalls in the southern Udzungwa Mountains in Tanzania. At about 20,000 m2 (220,000 sq ft), this was one of the smallest natural distribution known for any vertebrate species, but it was abundant within its tiny range, and had a population of around 17,000 individuals. Following the construction of the Kihansi Dam, it became extinct in the wild. A captive breeding program is maintained at a few U.S. zoos, and it is hoped the Kihansi spray toad can be reintroduced back into its natural range.
Extinction in the wild
The extinction in the wild of the Kihansi spray toad was mainly due to habitat loss following the construction of Kihansi Dam in 1999, which reduced the amount of water coming down from the waterfall into the gorge by 90 percent. This led to the spray toad's microhabitat being compromised, as it reduced the amount of water spray, which the toads were reliant on. A sprinkler system that mimicked the natural water spray was not yet operational when the Kihansi Dam opened. In 2003 there was a final population crash in the species. This coincided with a breakdown of the sprinkler system during the dry season, the appearance of the disease chytridiomycosis, and the brief opening of the Kihansi Dam to flush out sediments, which contained pesticides. The last confirmed record of wild Kihansi spray toads was in 2004.
Survival in captivity
The Bronx Zoo initiated a project where almost 500 Kihansi spray toads were taken from their native gorge in 2001 and placed in six U.S. zoos as a possible hedge against extinction. Initially its unusual life style and reproduction mode caused problems in captivity, and only Bronx Zoo and Toledo Zoo were able to maintain populations. By December 2004, less than 70 remained in captivity, but when their exact requirements were discovered greater survival and breeding success was achieved. In November 2005, the Toledo Zoo opened an exhibit for the Kihansi spray toad, and for some time this was the only place in the world where it was on display to the public. The Toledo Zoo now has several thousand Kihansi spray toads, the majority off-exhibit. The Bronx Zoo also has several thousand Kihansi spray toads, and it opened a small exhibit for some of these in February 2010. In 2010 Toledo Zoo transferred 350 toads to Chattanooga Zoo, which has created a small exhibit for them. Groups numbering in the hundreds are now also maintained at Detroit Zoo and Omaha's Henry Doorly Zoo.
In August 2010, a group of 100 Kihansi Spray Toads were flown from the Bronx Zoo and Toledo Zoo to their native Tanzania, as part of an effort to reintroduce the species into the wild, using a propagation center at the University of Dar es Salaam. In 2012, scientists from the center returned a test population of 48 toads to the Kihansi gorge, having found means to co-inhabit the toads with the chytrid fungus. They plan to release a total population of about 1,800 toads after monitoring the initial release for several months.
- Channing, A., Howell, K., Loader, S., Menegon, M. & Poynton, J. (2009). "Nectophrynoides asperginis". IUCN Red List of Threatened Species. Version 2011.2. International Union for Conservation of Nature. Retrieved 8 January 2012.
- Channing and Howell. (2006). Amphibians of East Africa. Pp. 106-107. ISBN 3-930612-53-4
- Toledo Zoo TZ to Tanzania: A Kihansi Spray Toad Fact Sheet. Accessed 8 January 2011
- New York Times (1 February 2010). Saving Tiny Toads Without a Home. Accessed 8 January 2012.
- Science Daily (17 August 2010). Kihansi Spray Toads Make Historic Return to Tanzania. Accessed 8 January 2011.
- ISIS (2012). Nectophrynoides asperginis. Version 23 December 2011. Accessed 8 January 2012.
- World Conservation Society (2 February 2010). Extinct toad in the wild on exhibit at WCS's Bronx zoo. Accessed 8 January 2011
- Tanzania: Kihansi Toads Pass Anti-Fungal 'Test', by Abdulwakil Saiboko, Tanzania Daily News, 14 August 2012.
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