They are increasingly threatened by climate change.
Humans have hunted many apex predators close to extinction, but in some parts of the world these predators are now returning. The wolf is both an apex predator and a keystone species, affecting its prey's behaviour and the wider ecosystem.īecause apex predators have powerful effects on other predators, on herbivores, and on plants, they can be important in nature conservation. This effect, called mesopredator release, occurs in terrestrial and marine ecosystems for instance, in North America, the ranges of all apex carnivores have contracted whereas those of 60% of mesopredators have grown in the past two centuries. For example, reduction in the population of sperm whales, apex predators with a fractional trophic level of 4.7, by hunting has caused an increase in the population of large squid, trophic level over 4 (carnivores that eat other carnivores). The removal of top-level predators, often through human agency, can cause or disrupt trophic cascades. Such wide-ranging effects on lower levels of an ecosystem are termed trophic cascades. When introduced to subarctic islands, for example, Arctic foxes' predation of seabirds has been shown to turn grassland into tundra. They are central to the functioning of ecosystems, the regulation of disease, and the maintenance of biodiversity. Effects on ecosystem Īpex predators can have profound effects on ecosystems, as the consequences of both controlling prey density and restricting smaller predators, and may be capable of self-regulation. Humans are not considered apex predators because their diets are typically diverse, although human trophic levels increase with consumption of meat. Predators that exert a top-down control on organisms in their community are often considered keystone species.
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Removal of badgers (in a trial investigating bovine tuberculosis) caused hedgehog densities to more than double. As a terrestrial example, the badger, an apex predator, predates on and also competes with the hedgehog, a mesopredator, for food such as insects, small mammals, reptiles, amphibians and the eggs of ground-nesting birds. A lake manipulation study found that when the non-native smallmouth bass was removed, lake trout, the suppressed native apex predator, diversified its prey selection and increased its trophic level. Non-native predatory fish, for instance, have sometimes devastated formerly dominant predators. Īpex predators affect prey species' population dynamics and populations of other predators, both in aquatic and in terrestrial ecosystems.
The great skua is an aerial apex predator, both preying on other seabirds and bullying them for their catches.
These include interactions via ecotourism, such as with the tiger shark, and through rewilding efforts, such as the proposed reintroduction of the lynx. More recently, humans have started interacting with apex predators in new ways. Humans have for many centuries interacted with apex predators including the wolf, birds of prey and cormorants to hunt game animals, birds, and fish respectively. The apex predator concept is applied in wildlife management, conservation and ecotourism.Īpex predators have a long evolutionary history, dating at least to the Cambrian period when animals such as Anomalocaris dominated the seas.
Food chains are often far shorter on land, usually limited to being secondary consumers – for example, wolves prey mostly upon large herbivores (primary consumers), which eat plants (primary producers). Īpex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic levels. The great white shark (bottom) was originally considered the apex predator of the ocean however, the killer whale (top) has proven to be a predator of the shark.Īn apex predator, also known as an alpha predator or top predator, is a predator at the top of a food chain, without natural predators.
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