Fig. 3.2.

Interactions between predators may affect ecological communities more broadly. In this example, cats are shown as the smaller (meso)predator and dingoes as the top order, or apex predator. In (a), dingoes suppress the cat population (‘mesopredator suppression’), thus reducing predation by cats on small prey species such as ground-active birds. In (b), if the population of top order predators is absent, such as where controlled by managers, the population size and impacts of cats on small prey may increase (‘mesopredator release’). Blue arrows show direct interactions between species, arrow width shows the relative strength of these interactions, and + and - signs show the direction of impact of one species on another. The grey arrow indicates an indirect interaction: dingoes may not hunt small birds, but can have a positive effect on their populations via their suppressive effect on cats. Comparable responses may occur in situations where foxes, rather than dingoes, are the top-order predator; but may become more complex in situations where there are more layers of predators (such as dingoes, foxes and cats).