Mammal migration in Serengeti is shaped by the diet of grazers

The article written by Elizabeth Pennisi on Science.org, delves into the fascinating migration of zebras, wildebeests, and Thomson’s gazelles in the Serengeti, spanning from Tanzania into Kenya, unraveling the intricacies of this natural spectacle. Approximately 200,000 zebras, 1.3 million wildebeests, and 400,000 Thomson’s gazelles embark on an 800-kilometer journey each April, creating a breathtaking procession. Scientists, led by T. Michael Anderson of Wake Forest University, conducted an extensive study over eight years, employing camera traps, GPS tracking, and dung analysis to gain insights into the forces guiding this migration.

Contrary to previous assumptions, the researchers discovered that zebras and wildebeests exhibit little time separation in their movements, suggesting a co-migration pattern. The dietary preferences of each species emerged as a significant factor influencing their behavior. Zebras, with wide muzzles, predominantly consume coarse, tall grasses, while wildebeests, with narrower muzzles, focus on legumes. The gazelles, with smaller stomachs and slower digestion, rely on high-nutrient foods like forbs and young herbaceous plants.

Surprisingly, the study also found that the species’ interactions were not significantly influenced by predators, challenging earlier theories. Instead, the timing of the migration was closely tied to dietary considerations. Fires and intense rains were identified as factors that could alter migration timing. After a fire, nutrient-rich new growth can affect the dynamics, while early-year rain leading to excess tall grasses makes gazelles more dependent on larger grazers.

The research indicates that climate change might pose a threat to this remarkable migration. Increased or widespread fires could disrupt the migration dynamics, potentially jeopardizing the health and abundance of these herds. The findings emphasize the intricate interdependence of species and the delicate balance that sustains this extraordinary natural phenomenon in the Serengeti ecosystem.