An estimate that as many as 1.3 million wildebeest move across the Serengeti Mara landscape each year has been cut down to size using AI
By Graeme Green
9 September 2025
The wildebeest migration of the Serengeti involves fewer animals than we had thought
Nicholas Tinelli / Alamy
East Africa’s “Great Migration” is generally estimated to involve as many as 1.3 million wildebeest. But in reality, fewer than 600,000 of the animals might move across the Serengeti Mara landscape each year, according to an AI analysis of satellite images.
The Great Migration sees wildebeest, zebra and antelopes move between feeding and breeding grounds in Kenya and Tanzania, while also trying to dodge predators including lions, crocodiles and hyenas.
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Assessing the number of animals involved is a tough task, traditionally achieved using crewed aerial surveys. Researchers can only survey a small area at a time, however, so they use statistical models to extrapolate densities across unsurveyed regions, which can introduce errors given herds are unevenly distributed and constantly on the move.
Satellite surveys can avoid these problems because one photo can cover hundreds of thousands of square kilometres, reducing the chance of double-counting animals and removing the need for extrapolative projections. It is impractical to manually count wildebeest in such vast images, but the animals can be tallied using AI instead. “Automation through AI does provide greater consistency and accuracy in counting,” says Isla Duporge at the University of Oxford.
For the new study, Duporge and her colleagues trained two deep-learning models – U-Net and YOLOv8 – to identify wildebeest using a dataset of images in which 70,417 of the animals had been manually labelled. Both models were then applied to over 4000 square kilometres of high-resolution satellite imagery. The images were captured on 6 August 2022 and 28 August 2023.