Apex Predators

Apex predators (also known as alpha, super-, top-level predators or top predators) are predators that have no predators of their own, residing at the top of their food chain.[3] Apex predator species are often at the top of long food chains, where they have a crucial role in maintaining the health of their ecosystems.

Zoologists define predation as the killing and consumption of another organism (which generally excludes parasites and most bacteria).[4] In this context, "apex predator" is usually defined in terms of trophic levels, which comprise "hierarchical strata of a food web characterized by organisms which are the same number of steps removed from the primary producers."[5] In other words, an apex predator exists at or near the top of its food-chain. Primary, secondary, tertiary, and higher level consumers occupy successive trophic levels. One study of marine food webs defined apex predators as greater than trophic level four.[6] The apex predator concept is commonly applied in wildlife management and conservation, as well as in ecotourism.

Food chains are often far shorter on land, with the top of the food chain limited to the third trophic level, as where such predators as the big cats, crocodilians, hyenas, wolves, or giant constrictor snakes prey upon large herbivores. Apex predators need not be hypercarnivores. For example, grizzly bears and humans[7] are each apex predators, and yet they are omnivores that eat vegetable material as well as meat. A dog, more carnivorous than either humans or most bears, is usually more of a scavenger than a predator, but as an occasional killer of livestock or wildlife and a participant in some human hunts it qualifies as a superpredator in much of its extensive range. In this sense, an apex predator can be defined as being too difficult to kill for them to be a regular source of food for other predators. Some animals may be superpredators in some environments but not others, such as domestic dogs and cats, both of which can ravage ecosystems, as the introduction of feral cats to Australia demonstrates[citation needed].