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Location Kenya, Central Province
Central coordinates 36o 25.62' East  0o 6.48' South
IBA criteria A1, A2, A3
Area 4,600 ha
Altitude 2,340 - 2,400m
Year of IBA assessment 2007

NatureKenya



Site description Lake Ol' Bolossat, Central Province's only natural lake, is an internal drainage basin whose swamps have a high salt content possibly due to high evaporation rates and partly to the nature of sediments that constitute the area (Krhoda 1992). The lake is situated in the valley between the northwestern slopes of Aberdares Mountains and Dundori Ridge which are the main catchments. The altitude ranges from 2,340 - 2,400 meters above sea level, receiving an average precipitation of 975 - 1,100 mm pa. The Lake covers an area of 43.3 sq.km. of which open water covers about 4 sq.km. This drainage basin, Ewaso Ngiro North Basin covering 210,226 sq.km., is Kenya's largest. It offers a variety of habitats ranging from open water through floating marsh and swamps, open grasslands and riverine forests along rivers and springs that feed the lake.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Maccoa Duck Oxyura maccoa resident  2007-2010  present individuals  good    Near Threatened 
Grey Crowned-crane Balearica regulorum resident  2007  present individuals  good    Endangered 
Jackson's Widowbird Euplectes jacksoni resident  2007  present individuals  good  A2, A3  Near Threatened 
Sharpe's Longclaw Macronyx sharpei resident  2007  present individuals  good  A1, A2, A3  Endangered 

Local conservation groups The local conservation group below is working to support conservation at this IBA.

Name Year formed
Nyahururu Bird Club 2008

Habitats

IUCN habitat Habitat detail Extent (% of site)
Wetlands (inland) Freshwater lakes and pools  9%
Grassland Grassland - montane  91%

Land ownership  Unprotected.

Land use

Land-use Extent (% of site)
agriculture 70%
Notes: Small and large-scale intensive agriculture.
other 5%
Notes: Quarrying
forestry 1%
Notes: Farm woodlots
nature conservation and research 15%
Notes: Wildlife conservation

Other biodiversity  Hippopotamuses, estimated at over 200 individuals, which graze overnight.

Acknowledgements The British Ornithologists’ Union (BOU) for providing funds for research. The Wetlands Programme and Office of the Deputy Director Biodiversity Research & Monitoring at Kenya Wildlife Service headquarters. The Chairman, Lake Ol Bolossat Conservation Network, Mr. Joseph Mbugua, for logistics. Field assistants and community local guides Teresia Maina and Paul Ndegwa, and Catherine Wambui of Kenya Forest Service based at South Marmanet Forest, for their field work facilitation

References Survey of globally-threatened birds at Lake Ol Bolossat Grasslands, central Kenya by Wanyoike Wamiti,Philista Malaki & Andrew Mwangi.Research Reports of the Directorate of Research & Collections, National Museums of Kenya: Ornithology, 78 (2007)

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Recommended citation  BirdLife International (2014) Important Bird Areas factsheet: Lake Ol' Bolossat. Downloaded from http://www.birdlife.org on 21/04/2014

To provide new information to update this factsheet or to correct any errors, please email BirdLife