THE HABITAT Nairobi National Park lies to the south-southeast of the capital of Kenya, Nairobi, where the Athi Plains meet the Eastern escarpment of the Rift Valley. These plains form part of the semi-arid highland plateau lying between the coast and the Rift Valley. Both the city itself, and the Park bordering it, are a meeting place of two generally distinct types of landscape and climate. While to the east-southeast are semi-arid plains with grasslands and scattered trees, the western-north- western parts are higher, hilly, cooler, more humid and support lush forests. The combination of latitude-a little over one degree south of the Equator -and altitude-average of 1600 m. (5000-5500 ft.) -combine to give Nairobi a most equable climate where the temperature varies during the year between about 11 degrees and 27 degrees centigrade (mean minimum and mean maximum for eight years). However, considerable changes are usually experienced within each day and a rise from 14 degrees C at 0600 hours to 22 degrees at 1100 hours is not unusual. Nairobi Park has a unique concentration of wild animals living in their natural habitat less than 10 km. from the centre of a modern city of half a million people. The only interference with the natural course of events in the Park is that normally required for the proper management of a game park, such as maintenance of roads and dams, and, in this particular case, partial fencing towards the city.