Ecology of the giraffe in Tsavo East National Park, Kenya

The decrease in woody vegetation in Tsavo National Park has probably had adverse effects on woodland-adapted herbivores, including the giraffe (Girafa camelopardalis). In an ecological study we attempted to assess this species’ density, habitat preference and utilization, and population dynamics, using mainly road strip counts and identification of individual animals. Population structure varied seasonally and locally, indicating differential distribution of sex/age classes. Records on individually known animals suggested an annual mortality rate of c. 10% for adult plus subadult animals. Of fifteen newborn young, five (33%) survived to 1 year of age, four (27%) to 2 years; in young males mortality appeared to be somewhat higher than in females, but the adult/subadult sex ratio was near unity. The mean calving interval was 22.6 months. Overall mean density was about 0-2 animals/km2. Vegetation-specific densities indicated a marked preference for woody vegetation generally, and some preference for riverine areas in the dry season. Data on seasonal distribution showed marked concentrations near rivers in the dry season and dispersal into deciduous woodlands away from rivers in the rainy season. The seasonal movements were correlated with, and presumably causally related to, rainfall and the condition of the vegetation; they involved distances of 20-30 km, rarely up to 50 km. Home ranges measured on average 160 km2, with maxima of 650 km2 in males and 480 km2 in females.
The results are compared with those of other studies, and their implications for management are discussed. The future of the giraffe in Tsavo East National Park depends on the development of the woody vegetation inside the park, and probably also on the future pattern of land use outside, as some giraffes appear to move out of the park at times.

Last Updated
January 26, 2021
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