Nairobi, Kenya (22 April 2009)—Populations of major wild grazing animals that are the heart and soul of Kenya's cherished and heavily visited Masai Mara National Reserve—including giraffes, hartebeest, impala, and warthogs—have "decreased substantially" in only 15 years as they compete for survival with a growing concentration of human settlements in the region, according to a new study published today in the May 2009 issue of the British Journal of Zoology.
The study, analysed by researchers at the Nairobi-based International Livestock Research Institute (ILRI) and led and funded by World Wide Fund for Nature (WWF), is based on rigorous, monthly monitoring between 1989 and 2003 of seven "ungulate," or hoofed, species in the Maasai Mara National Reserve, which covers some 1500 square kilometers in southwestern Kenya. Scientists found that a total of six species—giraffes, hartebeest, impala, warthogs, topis and waterbuck—declined markedly and persistently throughout the reserve.
The study provides the most detailed evidence to date on declines in the ungulate populations in the Mara and how this phenomenon is linked to the rapid expansion of human populations near the boundaries of the reserve. For example, an analysis of the monthly sample counts indicates that the losses were as high as 95 percent for giraffes, 80 percent for warthogs, 76 percent for hartebeest, and 67 percent for impala. Researchers say the declines they documented are supported by previous studies that have found dramatic drops in the reserve of once abundant wildebeest, gazelles and zebras.
"The situation we documented paints a bleak picture and requires urgent and decisive action if we want to save this treasure from disaster," said Joseph Ogutu, the lead author of the study and a statistical ecologist at ILRI. "Our study offers the best evidence to date that wildlife losses in the reserve are widespread and substantial, and that these trends are likely linked to the steady increase in human settlements on lands adjacent to the reserve."
Researchers found the growing human population has diminished the wild animal population by usurping wildlife grazing territory for crop and livestock production to support their families. Some traditional farming cultures to the west and southwest of the Mara continue to hunt wildlife inside the Mara Reserve, which is illegal, for food and profit.
The Mara National Reserve is located in the northernmost section of the Mara—Serengeti ecosystem in East Africa. The reserve is bounded by Tanzania's Serengeti National Park to the south, Maasai pastoral ranches to the north and east, and crop farming to the west. The area is world-famous for its exceptional wildlife population and an annual migration of nearly two million wildebeest, zebra and other wildlife across the Serengeti and Mara plains.
Ogutu and his colleagues focused much of their attention on the rapid changes occurring in the large territories around the Mara Reserve known as the Mara ranchlands, which are home to the Maasai. Until recently, most Maasai were semi-nomadic herders—known for their warrior culture and colorful red toga-style dress—who co-existed easily with the wildlife in the region.