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Predator-prey cycles

Ecology · Organisation of an ecosystem · note 3 of 4

Predator-prey cyclesSpec 4.7.2.1

In a stable community the numbers of predators and prey rise and fall in cycles.

  1. Prey numbers are high, so there is plenty of food for the predators.
  2. Predator numbers rise as they eat more prey and breed.
  3. Prey numbers fall as more of them are eaten.
  4. With less food, predator numbers fall.
  5. Fewer predators means fewer prey are eaten, so prey numbers rise again.
Line graph of number of organisms against time, showing prey (solid line) and predator (dashed line) numbers rising and falling in waves, with each predator peak a short time lag after the prey peak.Tap to enlarge
Predator and prey numbers cycle. The prey peak comes first and the predator peak follows after a time lag.