Overview

• Published in PNAS Nexus on September 9, 2025, the study reports fewer than 600,000 migratory wildebeest based on satellite imagery from 2022 and 2023.
• High-resolution Maxar images (33–60 cm) from August 6, 2022, and August 28, 2023, were analyzed with two independent models, U-Net and YOLOv8.
• The models produced closely aligned counts of 324,202 and 337,926 for 2022, and 502,917 and 533,137 for 2023, indicating consistent AI detection performance.
• The findings undercut the long-cited 1.3 million figure derived from crewed aerial surveys, with authors cautioning that canopy cover, survey timing, and area limits can cause slight undercounts.
• The research team released its code on GitHub and is developing similar satellite-AI methods for other species, including African rhinos.