Predators and prey

Predators are animals that eat other animals. Prey are the animals that get eaten. The size of the predator population and prey population depend on each other.

Lynx and hares

The Canadian lynx eats the snowshoe hare. The size of the two populations was estimated each year for 75 years from the number of animals caught by fur traders. There is a rise and fall in the snowshoe hare population with the lynx population following two years afterwards. No other cat is so dependent on a single prey species, which is why there is such a clear pattern of interdependence between the two populations.

The predator/prey dynamic between canadian lynx and snowshoe hare populations

If the prey population grows, predator numbers will respond to the increased food supply by increasing as well. But the growing predator population will eventually reduce the food supply to the point where it can no longer be sustained.

Ladybirds and aphids

The simulation shows how the population of ladybirds - predators - and the population of aphids - their preychanges over time:

Look at the effects of increasing the predator population, or increasing the prey population, at the start. Toggle the graph on and off to see how the populations change.