Conservation maps show world’s largest mammal migration — and the urgent threat it faces

The seasonal movements of two migratory antelope species — the white-eared kob and tiang — across South Sudan’s expansive wetlands and Ethiopia’s Gambella National Park have been mapped in unprecedented detail to help better conserve them.

Covering an area of over 100 000km² — roughly seven times larger than Serengeti National Park — these maps reveal the largest known land mammal migration on Earth, also known as the Great Nile Migration.

About 5 million kob and 400 000 tiang, alongside other hooved mammals, also known as ungulates, undertake complex, long-distance journeys to access essential wet and dry-season habitats annually, according to the Convention on Migratory Species (CMS).

Their routes take them between the Badingilo and Boma national parks in South Sudan. Some migrate further north to Gambella National Park, an important dry-season refuge, particularly for kob, from February to May.

The Convention on Migratory Species said the newly released migration maps form part of the Atlas of Ungulate Migration, which was developed by the Global Initiative on Ungulate Migration under the Convention on the Conservation of Migratory Species of Wild Animals. 

“Publicly available online, the atlas and the new maps aim to support conservation planning, infrastructure development and policy-making to maintain critical ecological connectivity, thus preserving essential habitats for migratory species while reducing the potential for human-wildlife conflict.”

“The detailed migration maps … highlight the interconnectedness of landscapes across South Sudan and Ethiopia and underscore the urgent need to balance infrastructure development with the survival of migratory species,” said Amy Fraenkel, the executive secretary of the CMS.

The maps build on recent aerial surveys and tracking data, which were released in June last year by African Parks and South Sudan’s ministry of wildlife conservation and tourism. 

During these surveys, biologists estimated 5 to 7 million migratory animals across four species — white-eared kob, tiang, Mongalla gazelle and Bohor reedbuck. 

For the kob, the maps significantly expand upon earlier tracking studies conducted by the Ethiopian Wildlife Conservation Authority between 2013 and 2015, providing new insights into how migrations connect critical habitats across international boundaries, the CMS said.

Seeing the full extent of these migrations is awe-inspiring, but also daunting, said Kumara Wakjira, director general of the Ethiopian Wildlife Conservation Authority. “Although it will be challenging, we are committed to assuring that these landscapes remain protected to sustain the movement of kob and other migratory species in Ethiopia into the future.”

Migration routes for kob and tiang, which are now mapped clearly between seasonal ranges, highlight essential corridors needed for their survival through extreme seasonal conditions. 

The CMS said that as human populations and infrastructure expand, these detailed maps offer critical information to mitigate impacts of large-scale projects, particularly energy infrastructure.

“Oil extraction poses a pressing concern, notably within a development area known as Block B2, operated by South Africa’s Strategic Fuel Fund and South Sudan’s Nilepet, covering areas critical for both kob and tiang migrations. 

“Without careful and informed planning, the oil exploration set to begin in 2025 could seriously disrupt wildlife migration, increase human encroachment and escalate illegal hunting,” the CMS said. “The rising incidence of illegal tiang harvesting along roads already shows how essential it is to plan infrastructure with wildlife protection in mind.”

Humans and wildlife have shared this landscape since time immemorial, and even amid new pressures, they can continue to do so, said Grant Hopcraft, a member of the scientific advisory team of the Global Initiative on Ungulate Migration, which led the migration analyses and mapping. 

“If used, these migration maps, based on the best available science, are important tools in ensuring that the needs of both wildlife and humans are balanced.” 

In South Sudan, conservation based on sound management and collaboration with local communities is urgently needed. The CMS said that increasing illegal wildlife trade and the potential impact of petroleum extraction highlight the importance of safeguarding the region’s migratory wildlife. 

“South Sudan and Ethiopia have a unique opportunity to preserve one of the world’s most remarkable natural phenomena for future generations, potentially leveraging conservation and tourism for sustainable economic growth.

“We are dedicated to conserving and studying the migrations here in South Sudan, which are not only globally significant, but part of our national identity,” said Malik Morjan, a professor of wildlife biology at the University of Juba, South Sudan, and a key contributor of data for the maps.

The CMS added that conserving migratory species and “ensuring that spectacular wildlife movements continue into the future” directly supports the achievement of key global commitments such as the Kunming-Montreal Global Biodiversity Framework and the UN Sustainable Development Goals.