Kenya’s wildebeest annual migration dramatically declines by 90% due to fences
The iconic wildebeest migration in Kenya’s Maasai Mara has declined dramatically over the past five years, with populations now occupying just 10% of their historic range, according to new research. Conservationists warn that fences and other man-made barriers are fragmenting the ecosystem, threatening one of Africa’s most famous wildlife spectacles.
The study, led by researchers from the Smithsonian’s National Zoo and Conservation Biology Institute (NZCBI) in Washington DC in partnership with the Global Initiative on Ungulate Migration (GIUM), shows that Mara-Loita white-bearded wildebeest populations have lost nearly 90% of their historic migratory routes since 2020.
Located just north of the Serengeti, the Maasai Mara has long hosted a smaller, yet significant, wildebeest migration, which is now rapidly collapsing. New maps published in the Atlas of Ungulate Migration reveal the severe impact of fencing on the long-distance movements of these hooved mammals, known as ungulates.
Dr. Jared Stabach, terrestrial science lead with the Smithsonian’s Movement of Life Initiative, has studied the Mara wildebeest since 2010. He said, “Over the past decade, the Mara ecosystem has undergone profound changes and offers a warning to other grassland regions facing similar human pressures. As land use shifts in East Africa, there is tremendous conservation urgency in this region.”
Historically, more than 100,000 wildebeest migrated from their wet season grounds in western Greater Mara to the Loita Plains in the northeast. But land sales and subdivision for agriculture and private property, approved by the government in the early 1980s, led to the rapid expansion of fencing across Narok County in the mid-2010s. Today, most wildebeest are largely resident, with very few completing the full migration.
The consequences have been severe. Estimates from the Wildlife Research and Training Institute (WRTI) and Kenya’s Directorate of Resource Surveys and Remote Sensing (DRSRS) indicate that the Mara wildebeest population has dropped from over 100,000 to fewer than 25,000.
“Migration and population abundance go hand in hand,” Dr. Stabach explained. “Without the ability to move to water, forage, and calving grounds at critical times, populations collapse.” He added that climate change, particularly more frequent droughts, is compounding the pressures on these migratory herds.
The GIUM maps and fact sheets provide detailed guidance for conservation planning, identifying key corridors that must remain open for migration to survive. Dr. Joseph Ogutu, a co-researcher from the University of Hohenheim in Germany, emphasized, “Human development and wildlife migration in Kenya don’t have to be mutually exclusive. Maps can pinpoint where animals most need freedom of movement. Active restoration of blocked corridors is now essential.”
While the collapse of migrations in Kenya is striking, research from elsewhere in Africa shows that removing fences can allow ungulate migrations to recover. Conservationists believe that with careful planning, it is possible to balance human land use with the needs of wildlife.
The research team continues to monitor wildebeest movements in the Greater Mara Ecosystem to better understand the impact of fencing and guide future conservation strategies.
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