Livestock Feeding Ecology and Resource Utilization in a Nomadic Pastoral Ecosystem

(1) Seasonal patterns of forage selection, diet diversity, and habitat use were quantified for livestock managed by the Ngisonyoka Turkana in arid north-western Kenya by direct observation of free-ranging herds. The objective was to characterize the trophic niche segregation of livestock and their potential harvesting capacity for the heterogeneous vegetation resources of this ecosystem. (2) Cattle and camels were grazing and browsing specialists, respectively, while goats, sheep, and donkeys were generalists for both herbaceous and non-herbaceous vegetation. (3) Diet and habitat use were greatly influenced by season. Relative to brief rainy periods of resource abundance, long dry intervals of resource scarcity were times of reduced diet diversities (forage-class basis) for most species and greatly increased variation in habitat use. Livestock generally exhibited the greatest diet similarity in dry periods but were most segregated in terms of feeding habitats during these times. (4) The livestock in aggregate provided a very broad, opportunistic, and temporally stable trophic niche that resulted from equitable use of all forage classes, and their mobility provided a means to exploit the entire region. These attributes are essential for the persistence of nomads in this harsh, unpredictable environment, and are inimical to development tactics that serve to reduce livestock species diversity or restrict mobility.