An area of natural landscape at the grassland-forest boundary, only 7 km from the centre of Kenya’s capital city, Nairobi. The park’s varied habitats include open, rolling grass plains, riverine woodland, valley thicket and bush, artificial dams and ponds, rocky gorges and upland dry forest. The park is fenced along three sides, where it is adjacent to urban housing, industry, roads and airports; only the southern border, along the Embakasi and Athi rivers, is open for animal dispersal. Ecologically, the park is intimately linked to the Kitengela and Athi-Kapiti plains, which adjoin it to the south, forming a single ecological unit. Being close to the city centre and supporting a variety of large mammals, this park is a popular destination and a substantial money-earner for the Kenya Wildlife Service.
See Box and Table 2 for key species. Nairobi National Park is an important roosting site for Falco naumanni flocks on passage (up to 5,000 have been recorded), although numbers have declined markedly in recent years. The substantial area of undisturbed grassland is of great importance for species such as the restricted-range Euplectes jacksoni, which breeds here regularly after good rains. The avifauna is diverse, with a remarkable 516 species recorded, including 27 of Kenya’s 94 Somali–Masai biome species (23 of which are regular), and 25 of Kenya’s 67 African Highland biome species. The globally threatened Crex crex is a scarce visitor from the Palearctic, and the Near Threatened Balaeniceps rex and Acrocephalus griseldis have both been recorded once. Ardeola idae is a regular non-breeding visitor (May–October) in small numbers, and Parus fringillinus is fairly common in riverine Acacia woodland. Regionally threatened species include Struthio camelus (common); Anhinga rufa (scarce visitor); Casmerodius albus (regular visitor to dams and ponds); Ephippiorhynchus senegalensis (resident in small numbers); Hieraaetus ayresii (scarce resident in the forest); Stephanoaetus coronatus (at least one pair nests in the forest); Polemaetus bellicosus (several pairs have home ranges that include the park); Podica senegalensis (resident in small numbers on thickly-fringed sections of the rivers); and Buphagus africanus (moderately common).
Non-bird biodiversity: Nairobi National Park has healthy populations of an array of large mammals. The park is a rhino sanctuary and numbers of Diceros bicornis (CR) are steadily increasing. Acinonyx jubatus (VU) also occur in good numbers. Several plants growing on the rocky hillsides are unique to the Nairobi area, including Euphorbia brevitorta, Drimia calcarata, Murdannia clarkeana and an undescribed Crassula sp. The park protects an important area of Croton–Brachylaena–Calodendron upland dry forest. This distinctive Nairobi forest-type exists now only as small, ever diminishing fragments.
Pressure/threats to key biodiversity
The park is a dry season sanctuary for plains game, particularly Connochaetes taurinus, Equus quagga, and Taurotragus oryx. In the wet season, these animals disperse out of the park onto the open plains of Kajiado District to the south. This migratory movement is becoming increasingly constrained by sprawling settlements and industrial development on the Kitengela and Athi-Kapiti plains. The Kitengela was originally set aside as a game conservation area, but in the 1970s land hunger around Nairobi became acute and people were allowed to settle there. As a result, ranches were fenced off, farms and vegetable plots sprang into being, and human–wildlife conflict became intense. Meanwhile, industrial development around Athi river township, in particular an export processing zone, has cut off migration from the other direction. Only a narrow corridor is now available for animals to move through, much of this depending on the so-called Sheep and Goat Land. This agricultural research area has now allegedly been allocated to influential individuals. There are additional, though limited, options, such as purchase of land along the Mbagathi-Athi river frontage, and encouraging conservation-minded landowners to place easements on their land that restrict the uses to which it can be put. It is also important to ensure that wildlife within the dispersal areas has economic value to the landowners there, so that these areas remain suitable wildlife habitats. A local conservation group, the Friends of Nairobi National Park, is working with the Kenya Wildlife Service to explore these issues, and has begun an experimental Wildlife Conservation Lease programme. It is likely that the end result will be a ‘truncated ecosystem’, with some, but scaled-down, buffer areas remaining open for herbivore migrations. If this is not possible, and all the land around the park is fenced and developed, the park may effectively be strangled. Maintenance of the migration is important not just for the plains game and their predators, but for the ecosystem as a whole. Increased, year-round grazing pressure would greatly change the character of the grasslands and their bird communities. Species like Euplectes jacksoni, which have few areas of natural grassland left to nest in, could well be lost from the area as a result. Being very close to (and increasingly, surrounded by) the city, Nairobi National Park faces some obvious additional problems. Waste from some industries drains directly into the park and this has been difficult to control. Part of the park will be hived off for a major bypass road in the near future, and increased pressure on land puts the entire site at potential risk. On the other hand, its proximity to the city makes Nairobi National Park an unparalleled facility for public education about wildlife and conservation.