Apex predator

An apex predator occupies the top trophic position in an ecosystem and has no natural predators there. Its effects can extend through the food web by shaping prey populations and behavior.

Trophic cascade: A chain of effects across trophic levels caused by changes in the abundance or behavior of organisms at one level. Removing or restoring an apex predator can alter organisms far below it in the food web.
Gray wolf: A large canid native to much of the Northern Hemisphere that hunts in packs. Wolves are terrestrial apex predators in many ecosystems and can influence ungulate populations.
Yellowstone wolf reintroduction: The return of gray wolves to Yellowstone National Park beginning in 1995 after their local extirpation. This case prompted debate over how wolf recovery affected elk, vegetation, and other species.
Mesopredator: A medium-sized predator that is both a predator of smaller animals and potential prey of larger predators. Mesopredators occupy an intermediate position and may be suppressed by apex predators.
Ecological regime shift: A rapid, persistent change from one ecosystem state to another. It remains difficult to predict when predator loss or recovery can help push ecosystems into a new state.
Mesopredator release: An increase in medium-sized predators when larger predators decline or disappear. Apex predators can suppress smaller predators, so their loss may increase pressure on shared prey.
Orca: A large, highly social toothed whale found in oceans worldwide. Orcas occupy the top of many marine food webs, with diets that vary among populations.
Trophic rewilding: The restoration of ecological processes by reintroducing or conserving large animals and their interactions. Reintroducing apex predators is one way to restore top-down ecological processes.
Hyperpredation: A process in which abundant alternative prey sustains predators that then overhunt a vulnerable prey species. It shows how predator impacts can rise without the predator itself becoming an apex predator.
Alternative stable states: Distinct ecosystem configurations that can persist under similar environmental conditions. Predator effects may help maintain one state, while reversing their loss may not restore the former one.

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