Akuru, a bustling farming town, lies in the heart of Kenya's Rift Valley. Tractors and trailers laden with livestock, corn, bales of straw, farm produce and milk churns dispute right of way with juggernaut container lorries carrying fuel oil, tea, flowers and vegetables.

It straddles the Trans Africa highway - the only route to serve land-locked Uganda, Rwanda, Burundi and the Democratic Republic of Congo - and for anyone hoping to drive through, there's no way around. Nakuru can be a traffic-ridden, fume-filled hell-hole.

But there is one great compensation: from whichever direction the town is approached the eye is drawn to the south by a shimmering expanse of blue rimmed with pink. The blue is Lake Nakuru and the pink is hundreds of thousands of flamingoes. Framed with a backdrop of blue-tinged hills, part of the Mau range, it is a compelling sight - the heart of Lake Nakuru National Park.

One of a series of shallow alkaline lakes characteristic of the Rift Valley, Lake Nakuru was the first national park in Africa to be created primarily to conserve bird life. The great flocks of flamingoes, sometimes numbering a million or more, led famed ornithologist Roger Tory Peterson to describe it as "the world's most fabulous bird spectacle".

Nakuru National Park was officially opened in February 1961 by Sir Peter Scott, the internationally renowned ornithologist and artist, who described the lake as "a sight of incredible beauty and interest ... there can be no more remarkable ornithological sight in the world". Lake Nakuru was declared a Ramsar site (wetland of international importance) in 1990.

The bird life in this comparatively small park is rich and varied, with more than 450 species having been recorded. The lake, with an amazing number of water birds is, of course, the dominant feature, but the varied habitats of grassland, scrubby bush, marsh, forest, rock outcrops and craggy cliffs attract both migrant and resident species. Throughout the year there is plenty to keep the serious bird-watcher occupied.

The rugged terrain, like much of Africa, is softened by large tracts of green - acacia trees and marsh - and tall grass rippled by the breeze. This is offset by the water's blue and the glistening white crust of its soda ash surrounds.

Nakuru is the Anglicised form of the Maasai na-kurro, "that which is scraped bare" (grassless), referring to the bare expanse of soda ash of the lake bed and its rocky surrounds. For years it was popularly, but wrongly, assumed to mean "a place of swirling dust devils", from the clouds of soft dust raised by the wind when the lake is low.

The lake is 1,756 metres (5,670 feet) above sea level, with an average surface area of 30 km2 (11.5 miles2). It has no outlet and depends for replenishment on three seasonal rivers and rainfall, which averages about 1,000mm (40.75 inches) a year. Forty percent of this falls during the three-month period March to May.

Although the 188 km2 (72.5 miles2) park is acclaimed worldwide for its bird life, the mammals are also diverse and numerous. The Bohor reedbuck, seldom noticed in other parks, is easily recognised by the male's forward-curving horns. Over the years numbers of Rothschild's giraffe, distinguished by an extra 'horn', have been moved into the park from threatened habitats. They have done so well that some have been transferred to Uganda and private sanctuaries in Kenya to relieve population pressure at Nakuru.

The open grasslands host numbers of zebra, waterbuck, reedbuck, impala and Thomson's gazelle. In the acacia woodland (mainly Acacia xanthophloea, the yellow fever tree) the handsome bushbuck with ivory-tipped spiral horns and Kirk's dikdik, one of Africa's smallest antelopes, step gracefully through the dappled undergrowth. The scrubby bush is where one should find the massive and unpredictable African buffalo, standing 1.7m (5.5 feet) at the shoulder and weighing around 800 kgs ( 1,800 lbs). Lions pace the plains in search of prey and one or two may occasionally be seen at rest on the branch of a tree.

Olive baboons are common around the rocky outcrops to the south and an occasional klipspringer may be seen as it watches a visitor with great interest before scampering off across the cliff top. The rock hyrax, a small rodent-like mammal whose closest living relative is the elephant (see Travel Africa, edition 2, page 84), is usually to be seen in rocky areas, and the elusive leopard may, with luck, be sighted; generally a shy, nocturnal animal it is rarely seen in daylight. To catch a glimpse or, better still, to get a photo of one of Africa's most beautiful animals is indeed a bonus.

In 1980 Kenya's black rhino faced extinction following an unprecedented wave of wholesale poaching. In 1987 Lake Nakuru National Park became the first secure sanctuary for the Kenya Government's emergency Rhino Rescue programme. Sixteen black rhino were translocated from Solio Ranch in northern Kenya; more were brought in from threatened areas, followed by several white rhino, also from Solio and from the Natal Parks Board in South Africa. Both species are now well established and breeding.

The white rhino is not indigenous to Kenya, and to call it "white" is a misnomer as it is usually a dirty grey. Like the elephant (which does not occur in Nakuru) both species of rhino take on the colour of the earth they roll or wallow in. It is popularly assumed the animal was given its name from the Afrikaans wyt, meaning "wide", a reference to its wide, or square-lipped, mouth. (The black rhino could be described as the 'hook-lipped' rhino from its prehensile, triangular-shaped upper lip).

The two species are quite different in appearance and food preference. The white rhino is larger, a grazer and more placid than its less tractable black cousin, a browser. While the latter tends to keep to the thicker bush to browse on shrubs and bush, the white may be seen grazing in the open grassland.

On the lake both greater and lesser flamingoes are resident, the lesser in much larger numbers. The alkaline water provides ideal growing conditions for the blue-green algae (Spirulina) on which the lesser flamingo feed by filtering them through fine plates (lamellae) which line the inside of their peculiar beaks. The algae contain pigments (carotenes) which give the rich pink colour to the flamingoes' plumage. In contrast, greater flamingo feed on molluscs and small crustacea which they filter from the mud on the lake bottom. With different feeding habits the two species do not compete for food.

Normally about 50 tonnes of flamingo droppings go back into the lake every day, and are decomposed by bacteria into simple organic compounds. These the algae convert, using sunlight as an energy source, and they grow and reproduce at a rapid rate - thus the cycle is continued. However, the Njoro river, a crucial source of water for the lake, is increasingly polluted. There has been controversy over the inflow of treated sewage which, some experts say, contains insufficient bacteria to work on the flamingo droppings - factors causing concern for the sustained sources of the flamingoes' food supply.

The lake has dried out completely in very dry years, notably 1988 and 1996. When this happens, the flamingoes move away to other alkaline lakes where food may be found; Lake Bogoria to the north, Lake Elmenteita to the south-east and others further afield. But, as the rain falls again and the lake fills up, they return in the same great numbers. For a flamingo, there is nowhere like Lake Nakuru.

Flamingoes can be unpredictable and are not always present in vast numbers. However, one needn't worry, as there is always a wealth of bird and other life to compensate for the rare occasions when the flamingoes do not oblige.

On the rocky hillside of the eastern perimeter there is a forest of euphorbia trees (Euphorbia candelabrum). Grotesque with their upright branches and dark green colour, they are brightened by occasional short-lived white or pinkish flowers, which usually emerge at night. It is most unusual to find such an extensive stand of euphorbia and it is the biggest of its kind in Kenya.

A series of springs and streams along the northern and western edges of the lake provide a favoured resort for ducks and geese, which prefer the less alkaline water. Here, too, are: herons and egrets; black-winged and little stilts; sandpipers; several species of plover; an array of coots and quails; all sorts of seasonal migrants; the African snipe and the tiny and colourful malachite kingfisher. Monitor lizards, 1.5 metres in length, which look mighty fierce but are quite harmless, are also seen.

Unusually for a Kenyan national park, Lake Nakuru is fenced.There are conflicting opinions over what is perceived by some observers as excessive numbers of certain species, notably waterbuck and impala. Because animal movement is restricted there is concern that gene pools may be diminished. No one welcomes the thought of a reduction in animal numbers, but if the integrity of this beautiful park is to be preserved it may be inevitable.

Lake Nakuru National Park is easily accessible, has good roads and picnic sites and deserves a full day, at least, to take in the range of habitat, bird and animal life and vegetation contained in a comparatively small area. Although hot in the middle of the day, the forests and single trees give ample shade and there is usually a cooling breeze. A picnic lunch, serenaded by bird song, in the shade of some fine trees and accompanied by small weavers, sparrows, starlings and finches anxious for a few crumbs, could be a high point of a day in the park.

Many packaged visitors are taken to the lake shore to look only at the flamingoes and are driven out again. A great pity, as there is an awful lot more to see and the enthusiast will want to spend much longer.

David Round-Turner is a naturalist and writer based in Nairobi. He is an honorary warden of the Kenya Wildlife Service and a former district officer.

When the Flamingoes Come and Go - By David Round-Turner

Pretty well everything written or broadcast about Lake Nakuru proclaims the glorious sight of hundreds of thousands of massed pink flamingo, feeding, grunting and scuffling close to the shoreline.

When, as happened in the first half of 1999, there are only a few thousand to be seen, the chagrin of visitors is understandable. But flamingoes are unpredictable birds and are not always to be found in vast numbers on Lake Nakuru.

Over the first few months of the year the daily count was only about 50,000. They were mostly Greater flamingo which feed on crustacea and insects and do not depend on the blue-green algae (Spirulina) and diatoms on which the Lesser flamingo feeds. The lake has no outlet and the minerals carried into it over the years by feeder rivers remain, making the lake a highly alkaline medium. It is in alkaline waters that the blue-green algae grows best.

Lesser flamingo tend to come and go. They do not breed on Lake Nakuru, but move south to Lake Natron in northern Tanzania to do so. Occasionally they gather in quite large numbers in obscure places where an attractive food supply may be temporarily abundant.

The most likely cause of the current low numbers of Lesser flamingo on Lake Nakuru is an excess of fresh water, which has prevented the water chemistry returning to normal. A nutrient imbalance remains which inhibits the growth of the Spirulina algae which, under normal circumstances, can double in number every few hours during daylight. Fresh water flows into the lake from the springs at its northern end; from the municipal sewage works and, seasonally, from the Njoro and Nderit rivers to the west.

Pollution levels of water flowing into Lake Nakuru are monitored by the World Wide Fund for Nature (WWF) in conjunction with Kenya Wildlife Service (KWS). The Njoro River, a feeder stream to the west, is increasingly polluted with agricultural chemical and fertilizer residues. However, its flow has been reduced to a trickle for most of 1999 and, at present, is not regarded as a threat.

The municipal sewage works have been a source of controversy in the past, but since their rehabilitation the effluent is inoffensive and is not a significant source of pollution. The northern fresh water springs are natural and pollution-free.

KWS is alert to the ever-present risk of pollution - after all, the lake lies very close to a busy town with a population in the region of 300,000 - but at present the monitored levels show no signs of any pollution increase or anything approaching danger level.

El Nino brought the lake water level to its highest since 1979. The resulting reduction in food supply prompted a mass migration of Lesser flamingo to Lake Bogoria to the north (an hour's drive from Nakuru on a good tarmac road), where there are record numbers, mostly migrants from Nakuru. Every protected wildlife area faces a threat of some sort. At present, if there is a threat to Lake Nakuru's renowned flamingo population it is natural rather than man-made. As the water level recedes and the proportion of freshwater reduces there is every reason to expect the flamingoes to return to Lake Najuru. It's happened before.

Lake Nakuru factfile

Access
Most visitors will travel by road and will use the main entry gate, well signposted from Nakuru, 160km (100 miles) from Nairobi. Roads inside the park are good and four-wheel-drive is not necessary. There is an airstrip at Naishi in the park. Reputable tour operators in Nairobi run regular "seat-in-bus" safaris to Lake Nakuru. The railway is an alternative, from Mombasa, Nairobi or, indeed, any railway station in Kenya. Some road distances: Kisumu 187km (116 miles); Nyeri 183km (114 miles); Lake Bogoria 110km (68 miles); Maasai Mara National Reserve 320km (199 miles).

Accommodation
There is plenty of relatively inexpensive hotel accommodation in nearby Nakuru town and several safari lodges in the vicinity, but only two tourist lodges in the park: Sarova Lion Hill Lodge (134 beds) and Lake Nakuru Lodge (136 beds). Campsites range from the basic to special sites available with prior booking. There are two self-catering sets of bandas (cottages) at Lion Hill and the Naishi Guest House. Lake Nakuru Field Study Centre is a quiet hostel with kitchen, dining room, two dormitories with washrooms, and an amphitheatre. The hostels of the Wildlife Clubs of Kenya are located to the north of the lake, and can accommodate up to 50 visitors.

Top Sightings
Flamingoes, of course. Hundreds of thousands of them; white- and pink-backed pelican; Verreaux's eagle, Tawny eagle, Wahlberg's eagle, Martial eagle, Crowned hawk eagle, Bateleur, African fish eagle, Great sparrow hawk, osprey, three harrier species; migrant and resident waders, duck, geese, plover; seven species of sunbird; black and white rhino; lion; leopard; Rothschild's giraffe and a galaxy of extras.

Travel tip
Some basic suggestions to bring maximum enjoyment from a game drive: carry binoculars, camera and field guides, a hat, bottle of water, notebook and pen or pencil.

A National Park is no place for hurry. Time taken to stop and search the bush, foiage and undergrowth may be rewarded with a hidden natural history gem. The secret of good game-and bird-spotting is patience and careful searching.

Published in Travel Africa Edition Eight: Summer 1999 Text is subject to Worldwide Copyright (c)