Species → Plains Zebra
Plains Zebra
Equus quagga
What if it disappeared?
Impact ModerateThe zebra leads the great Serengeti migration, pushed ahead by food competition with the far more numerous wildebeest — by grazing the tallest, least nutritious stems first, it opens the way for the wildebeest and then the Thomson's gazelle, each benefiting from a different stage of grass regrowth depending on its order of passage.
DocumentedDetail
Anderson, T.M., Hepler, S.A., Holdo, R.M. et al. (2024). Interplay of competition and facilitation in grazing succession by migrant Serengeti herbivores. Science, 383(6684), 782–788.
Eight years of camera traps, GPS-collared animals, and fecal DNA metabarcoding reconstructed the precise arrival order and interactions of the three migratory species. The mechanism is a "push-pull" dynamic: the far more numerous wildebeest pushes the zebra ahead through direct competition, and the wildebeest's own grazing then facilitates access to nutritious regrowth for the trailing Thomson's gazelle.
Without the zebra to open the migration by grazing tall, fibrous stems first, the succession that later benefits the wildebeest and Thomson's gazelle could break down — but no study has removed the zebra from the migration to directly measure this cascading effect on the other two species.
ExtrapolatedDetail
Extrapolation à partir du mécanisme de succession documenté par Anderson et al. (2024), qui décrit l'ordre observé sans avoir testé sa rupture par retrait expérimental d'une espèce.
The zebra's role in this study is that of the first link in a three-species chain, each depending on the one before it. The mechanism is solid on eight years of observational data, but remains, like any non-experimental study, a correlation of order and facilitation rather than a direct causal test by removal.
What's missing to confirm it: A landscape-scale zebra exclusion experiment — hard to conduct on a migration of more than a million animals — would confirm whether the wildebeest and gazelle really do lose facilitated access to grass regrowth in its absence.
Documentation
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Anderson et al. (2024) — Interplay of competition and facilitation in grazing succession by migrant Serengeti herbivores, Science
Accessed August 10, 2026
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IUCN Red List — Equus quagga, statut et population
Accessed August 10, 2026
Last verified: August 10, 2026