Giraffe Metapopulation Demography

The Masai giraffe is the national animal of Tanzania and a globally iconic megaherbivore, but numbers have declined precipitously and the subspecies is now listed as endangered on the IUCN Red List. We studied the Masai giraffe population in the Tarangire Ecosystem over nine years to quantify population structure and demography of a large, free-living, wild megaherbivore population inhabiting a coupled human-natural system. This system supports a high density of giraffes and is representative of the current diversity of threats and conservation opportunities across the range of the species. We describe population structure (subpopulations within a metapopulation) and demographic structure (age and sex distributions) among subpopulations defined three ways: geographically discrete areas defined by human administrative boundaries; and subpopulation units derived from two types of social relationships among giraffes. The Tarangire giraffe metapopulation still functions via natural movements among subpopulations. Demographic variation exists among subpopulations, so maintaining habitat connectivity to ensure giraffe movements across the greater Tarangire Ecosystem is essential to long-term population viability.