Distribution and habitat
Kihansi Gorge and Falls in Tanzania prior to the construction of the hydroelectric dam. © T Davenport
Distribution
The toad’s habitat is very restricted (‘global range two hectares’ Poynton et al., Stuart et al., 2008). Four small populations lived in the spray wetlands associated with the Kihansi Falls in the Kihansi Gorge in the Udzungwa Mountains of eastern Tanzania. The Kihansi Falls are at an elevation of 660 to 940 metres above sea level.
The toad's were found at four sites
- Upper Falls, immediately below the main falls, 940 m
- Lower Falls near falls below main drop at 920 m
- Nearby to Lower Falls there is a small tributary the Mahala River falls
- A mid-gorge spray wetland at 600 m.
All four sites are very small. The Upper and Lower Falls sites are both approx 45m by 45m, and the remaining two are 30m by 10m and 20m by 20m respectively. Searches have revealed no additional populations.
Habitat
The spray toads natural habitat was the soaking wet herbaceous vegetation associated with the spray zone of the Kihansi Falls.
The growth of the vegetation, retarded by spray, was usually only 5-10cm, no more than 30cm;
Vegetation was predominantly
- club moss Selaginella kraussiana
- fern Tectaria gemmifera,
- low-growing Panicum grasses and
- East African forbs, for example
- Impatiens
- Streptocarpus,
- Begonia
- Alchemilla (Poynton et al., 1998).
The existence of Kihansi spray toad is dependent upon the heavy spray mist from the Kihansi Falls and its association with an apparently unique habitat, specialised spray wetland vegetation (see the Distribution and habitat section for details).