This area comprises a very shallow, strongly alkaline lake (3,300 ha), with surrounding woodland and grassland. Set in a picturesque landscape, the park abuts Nakuru town, an important and expanding agricultural and industrial centre. The lake catchment is bounded by Menengai Crater to the north, the Bahati Hills to the north-east, the Lion Hill ranges to the east, Eburu Crater to the south and the Mau escarpment to the west. Three major rivers, the Njoro, Makalia and Enderit, drain into the lake, together with treated water from the town’s sewage works and the outflow from several springs along the shore. Nakuru was first gazetted as a bird sanctuary in 1960 and upgraded to National Park status in 1968. A northern extension to the park was added in 1974. The foundation of the lake’s simple food chains is the cyanophyte Spirulina platensis, which often occurs as a unialgal bloom. At such times it can support huge numbers of Phoenicopterus minors and the fish Oreochromis alcalicus grahami (introduced in 1960 from Lake Magadi, IBA KE047, to curb mosquitoes). The fish in turn support a number of secondary consumers. The lakeshores are mainly open alkaline mud, with areas of sedge Cyperus laevigatus and Typha marsh around the river inflows and springs, giving way to grassland and a belt of Acacia xanthophloea woodland. Rocky hillsides on the park’s eastern perimeter are covered with Tarchonanthus scrub and magnificent Euphorbia forest.
See Box and Table 2 for key species. The lake is internationally famous for its populations of Phoenicopterus minor; numbers can reach 1.5 million at times, though drastic and unpredictable fluctuations occur. Undoubtedly Nakuru is a very important feeding site for this species; attempts by flamingos to breed here have not been successful. Other waterbirds have increased considerably in numbers and diversity since the introduction of fish in 1961. At times Nakuru is a major feeding ground for Pelecanus onocrotalus, which nest on rocky islets in nearby Lake Elmenteita and move to Nakuru daily to feed. Large numbers of Palearctic waders winter at Nakuru or use the site on passage, and Nakuru (at least in the past) has been a key site in the eastern Rift Valley flyway. Nakuru is rich in birds generally—some 450 species have been recorded. Globally threatened species include Ardeola idae (a non-breeding visitor, May to October); Phoenicopterus minor (a key feeding site for this species); Falco naumanni (a passage migrant, relatively common in the past); and Prionops poliolophus (probably resident in the Acacia woodland, where it has nested). Regionally threatened species include Podiceps cristatus (used to occur in numbers, but no recent records), Oxyura maccoa (no recent records), Casmerodius albus (up to 84 recorded, numbers have declined in recent years), Polemaetus bellicosus (sparse resident), Rynchops flavirostris (no recent records) and Euplectes progne (seasonal visitor, in long grassland).
Non-bird biodiversity: The park is a sanctuary for the rhinos Diceros bicornis (CR) and Ceratotherium simum (LR/cd), the latter introduced from South Africa. Giraffa camelopardalis rothschildi was also introduced into the park in 1977. The rare bat Hipposideros megalotis is resident. Other large mammals, some recently reintroduced, include Panthera leo (VU) and small numbers of Acinonyx jubatus (VU).
Pressure/threats to key biodiversity
Conflicts between conservation and development remain unresolved at Nakuru. On the one hand, the National Park is a major tourist attraction, with up to 300,000 foreign and local visitors each year, and the lake was designated as Kenya’s first Ramsar Site in 1990. On the other hand, Nakuru town is an important industrial and agricultural centre, whose growth directly affects the lake. Until recently, treatment of wastewater entering the lake from the town was inadequate. An expanded sewage treatment works is now in commission, but concerns about industrial pollution persist. The Lake Nakuru Conservation and Development Project, run by World Wide Fund for Nature, has been working for some years to improve urban environmental standards and encourage sustainable land-use in the catchment. Nearly half the catchment is now under cultivation, much natural vegetation has been removed, and dry-season river flows have reduced markedly while silt loads have risen. This problem will be severely exacerbated by recent deforestation in the Eastern Mau Forest Reserve (part of IBA KE051), which provides the catchment for much of Nakuru’s water. Encroachment and settlement in this forest (reportedly by as many as 28,000 people) needs to be reversed and natural vegetation allowed to regenerate, or the lake may have little future. The lake’s ecology, though relatively simple, is fragile. Populations of Spirulina, and the invertebrates, fish and flamingos that feed on it, can only be supported under specific, narrow conditions. Lake Nakuru’s levels fluctuate naturally due to little-understood interactions between hydrology, meteorology and geology. It is unknown how human pressures may have influenced the natural cycle A trough in waterbird numbers (other than flamingos) in the mid-1990s points to major changes in the food chain—specifically, a lack of fish and invertebrates—associated with a period of low lake levels. Waterbird populations have largely recovered since the El Niño event of 1998, when the lake level rose substantially. The National Park is now entirely surrounded by a 74-km electric fence that prevents movements of animals in or out. Large mammal populations in the park are expanding, and careful management will be needed to avoid serious ecological imbalances—for instance, giraffe are currently destroying the Acacia woodland through debarking. The requirements of threatened birds such as the Prionops poliolophus should also be considered in management planning, which presently is focused entirely on large mammals.
BirdLife International (2017) Important Bird Areas factsheet: Lake Nakuru National Park. Downloaded from
http://www.birdlife.org on 20/10/2017.