Apex predator

Last updated

The lion is the world's second-largest big cat and serves as an apex land predator in Africa. Lion waiting in Namibia.jpg
The lion is the world's second-largest big cat and serves as an apex land predator in Africa.
The saltwater crocodile is the largest living reptile and the dominant predator throughout its range. SaltwaterCrocodile('Maximo').jpg
The saltwater crocodile is the largest living reptile and the dominant predator throughout its range.
The great white shark (bottom) was originally considered an apex predator of the ocean; however, the orca (killer whale, top) has proven to be a predator of the shark. Comparison of size of orca and great white shark.svg
The great white shark (bottom) was originally considered an apex predator of the ocean; however, the orca (killer whale, top) has proven to be a predator of the shark.

An apex predator, also known as a top predator, is a predator [lower-alpha 1] at the top of a food chain, without natural predators of its own. [6] [7]

Contents

Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic levels. 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). The apex predator concept is applied in wildlife management, conservation, and ecotourism.

Apex predators have a long evolutionary history, dating at least to the Cambrian period when animals such as Anomalocaris and Timorebestia dominated the seas.

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. More recently, humans have started interacting with apex predators in new ways. These include interactions via ecotourism, such as with the tiger shark, and through rewilding efforts, such as the proposed reintroduction of the Iberian lynx.

Ecological roles

Effects on community

The great skua is an aerial apex predator, both preying on other seabirds and bullying them for their catches. Skua Runde.jpg
The great skua is an aerial apex predator, both preying on other seabirds and bullying them for their catches.

Apex predators affect prey species' population dynamics and populations of other predators, both in aquatic and terrestrial ecosystems. Non-native predatory fish, for instance, have sometimes devastated formerly dominant predators. 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. [9] As a terrestrial example, the badger, an apex predator, preys upon and also competes with the hedgehog, a mesopredator, for food such as insects, small mammals, reptiles, amphibians, and the eggs of ground-nesting birds. Removal of badgers (in a trial investigating bovine tuberculosis) caused hedgehog densities to more than double. [10] Predators that exert top-down control on organisms in their community are often considered keystone species. [11]

Effects on ecosystem

Apex 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. [12] They are central to the functioning of ecosystems, the regulation of disease, and the maintenance of biodiversity. [13] When introduced to subarctic islands, for example, Arctic foxes' predation of seabirds has been shown to turn grassland into the tundra. [14] Such wide-ranging effects on lower levels of an ecosystem are termed trophic cascades. The removal of top-level predators, often through human agency, can cause or disrupt trophic cascades. [15] [16] [17] For example, a 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 the large squid, with trophic level over 4 (carnivores that eat other carnivores). [18] This effect, called mesopredator release, [19] 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. [20]

Conservation

The wolf is both an apex predator and a keystone species, affecting its prey's behaviour and the wider ecosystem. Canis lupus pack surrounding Bison.jpg
The wolf is both an apex predator and a keystone species, affecting its prey's behaviour and the wider ecosystem.

Because apex predators have powerful effects on other predators, herbivores, and plants, they can be important in nature conservation. [21] Humans have hunted many apex predators close to extinction, but in some parts of the world, these predators are now returning. [22] They are increasingly threatened by climate change. For example, the polar bear requires extensive areas of sea ice to hunt its prey, typically seals, but climate change is shrinking the sea ice of the Arctic, forcing polar bears to fast on land for increasingly long periods. [23]

Dramatic changes in the Greater Yellowstone Ecosystem were recorded after the gray wolf, both an apex predator and a keystone species (one with a large effect on its ecosystem), was reintroduced to Yellowstone National Park in 1995 as a conservation measure. Elk, the wolves' primary prey, became less abundant and changed their behavior, freeing riparian zones from constant grazing and allowing willows, aspens, and cottonwoods to flourish, creating habitats for beaver, moose, and scores of other species. [24] In addition to their effect on prey species, the wolves' presence also affected one of the park's vulnerable species, the grizzly bear: emerging from hibernation, having fasted for months, the bears chose to scavenge wolf kills, [25] especially during the autumn as they prepared to hibernate once again. [26] The grizzly bear gives birth during hibernation, so the increased food supply is expected to produce an increase in the number of cubs observed. [27] Dozens of other species, including eagles, ravens, magpies, coyotes, and black bears have also been documented as scavenging from wolf kills within the park. [28]

Human trophic level

Humans sometimes live by hunting other animals for food and materials such as fur, sinew, and bone, as in this walrus hunt in the Arctic, but humans' status as apex predators is debated. 21 Walrus Hunt 1999.jpg
Humans sometimes live by hunting other animals for food and materials such as fur, sinew, and bone, as in this walrus hunt in the Arctic, but humans' status as apex predators is debated.

Ecologists have debated whether humans are apex predators. For instance, Sylvain Bonhommeau and colleagues argued in 2013 that across the global food web, a fractional human trophic level (HTL) can be calculated as the mean trophic level of every species in the human diet, weighted by the proportion that that species forms in the diet. This analysis gives an average HTL of 2.21, varying between 2.04 (for Burundi, with a 96.7% plant-based diet) and 2.57 (for Iceland, with 50% meat and fish, 50% plants). These values are comparable to those of non-apex predators such as the anchovy or pig. [29]

However, Peter D. Roopnarine criticized Bonhommeau's approach in 2014, arguing that humans are apex predators and that the HTL was based on terrestrial farming where indeed humans have a low trophic level, mainly eating producers (crop plants at level 1) or primary consumers (herbivores at level 2), which as expected places humans at a level slightly above 2. Roopnarine instead calculated the position of humans in two marine ecosystems, a Caribbean coral reef and the Benguela system near South Africa. In these systems, humans mainly eat predatory fish and have a fractional trophic level of 4.65 and 4.5, respectively, which in Roopnarine's view makes those humans apex predators. [lower-alpha 2] [30]

In 2021, Miki Ben-Dor and colleagues compared human biology to that of animals at various trophic levels. Using metrics as diverse as tool use and acidity of the stomach, they concluded that humans evolved as apex predators, diversifying their diets in response to the disappearance of most of the megafauna that had once been their primary source of food. [31]

Evolutionary history

Anomalocaris was an apex predator in the Cambrian seas. 20191203 Anomalocaris canadensis.png
Anomalocaris was an apex predator in the Cambrian seas.

Apex predators are thought to have existed since at least the Cambrian period, around 500 million years ago. Extinct species cannot be directly determined to be apex predators as their behavior cannot be observed, and clues to ecological relationships, such as bite marks on bones or shells, do not form a complete picture. However, indirect evidence such as the absence of any discernible predator in an environment is suggestive. Anomalocaris was an aquatic apex predator, in the Cambrian. Its mouthparts are clearly predatory, and there were no larger animals in the seas at that time. [32]

Carnivorous theropod dinosaurs including Allosaurus [33] and Tyrannosaurus [34] are theorized to have been apex predators, based on their size, morphology, and dietary needs.

A Permian shark, Triodus sessilis , was discovered containing two amphibians ( Archegosaurus decheni and Cheliderpeton latirostre ), one of which had consumed a fish, Acanthodes bronni , showing that the shark had lived at a trophic level of at least 4. [lower-alpha 3] [35]

Among more recent fossils, the saber-tooth cats, like Smilodon , are considered to have been apex predators in the Cenozoic. [36]

Interactions with humans

Dogs have been used in hunting for many centuries, as in this 14th century French depiction of a boar hunt. 37-svaghi, caccia,Taccuino Sanitatis, Casanatense 4182..jpg
Dogs have been used in hunting for many centuries, as in this 14th century French depiction of a boar hunt.

Hunting

Humans hunted with apex predators in the form of wolves, and in turn with domestic dogs, for 40,000 years; this collaboration may have helped modern humans to outcompete the Neanderthals. [37] [38] Humans still hunt with dogs, which have often been bred as gun dogs to point to, flush out, or retrieve prey. [39] The Portuguese Water Dog was used to drive fish into nets. [40] Several breeds of dog have been used to chase large prey such as deer and wolves. [41]

Eagles and falcons, which are apex predators, are used in falconry, hunting birds or mammals. [42] Tethered cormorants, also top predators, [43] have been used to catch fish. [44]

Ecotourism

Tiger sharks are popular ecotourism subjects, but their ecosystems may be affected by the food provided to attract them. Tiger shark size.svg
Tiger sharks are popular ecotourism subjects, but their ecosystems may be affected by the food provided to attract them.

Ecotourism sometimes relies on apex predators to attract business. [45] [46] Tour operators may in consequence decide to intervene in ecosystems, for example by providing food to attract predators to areas that can conveniently be visited. [45] This in turn can have effects on predator population and therefore on the wider ecosystem. [45] As a result, provisioning of species such as the tiger shark is controversial, but its effects are not well established by empirical evidence. [45] Other affected apex predators include big cats and crocodiles. [46]

Rewilding

The reintroduction of predators like the lynx is attractive to conservationists, but alarming to farmers. Lynx Lynx (10597310204).jpg
The reintroduction of predators like the lynx is attractive to conservationists, but alarming to farmers.

In some densely populated areas like the British Isles, all the large native predators like the wolf, bear, wolverine and lynx have become extirpated, allowing herbivores such as deer to multiply unchecked except by hunting. [47] In 2015, plans were made to reintroduce lynx to the counties of Norfolk, Cumbria, and Northumberland in England, and Aberdeenshire in Scotland as part of the rewilding movement. [48] The reintroduction of large predators is controversial, in part because of concern among farmers for their livestock. [48] Conservationists such as Paul Lister propose instead to allow wolves and bears to hunt their prey in a "managed environment" on large fenced reserves; however, this undermines the objective of rewilding. [48]

Notes

  1. ↑ Zoologists generally exclude parasites from trophic levels as they are (often much) smaller than their hosts, and individual species with multiple hosts at different life-cycle stages would occupy multiple levels. Otherwise they would often be at the top level, above apex predators. [5]
  2. ↑ However, humans had a network trophic level (NTL) of 4.27 in the coral reef system, compared to an NTL of 4.8 for the blacktip shark in the same system. Therefore, humans were not the topmost apex predator there. [30]
  3. ↑ Its trophic level would be exactly 4 if the fish's prey were pure herbivores, higher if the prey were themselves carnivorous.

Related Research Articles

<span class="mw-page-title-main">Predation</span> Biological interaction where a predator kills and eats a prey organism

Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation and parasitoidism. It is distinct from scavenging on dead prey, though many predators also scavenge; it overlaps with herbivory, as seed predators and destructive frugivores are predators.

<span class="mw-page-title-main">Cougar</span> Large species of cat native to the Americas

The cougar, also known as the puma, mountain lion, catamount, or panther, is a large cat native to the Americas, second in size only to the stockier jaguar. Its range spans the Canadian Provinces of the Yukon, British Columbia, and Alberta, the Rocky Mountains, and other areas in the Western United States. Their range extends further south through Mexico, where they are found in nearly every state, to the Amazon Rainforest and the southern Andes Mountains in Patagonia. The puma inhabits every mainland country in Central and South America, making it the most widely distributed large, wild, terrestrial mammal in the Western Hemisphere, and one of the most widespread on planet Earth. It is an adaptable, generalist species, occurring in most American habitat types. It prefers habitats with dense underbrush and rocky areas for stalking but also lives in open areas.

<span class="mw-page-title-main">Food web</span> Natural interconnection of food chains

A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community. Ecologists can broadly define all life forms as either autotrophs or heterotrophs, based on their trophic levels, the position that they occupy in the food web. To maintain their bodies, grow, develop, and to reproduce, autotrophs produce organic matter from inorganic substances, including both minerals and gases such as carbon dioxide. These chemical reactions require energy, which mainly comes from the Sun and largely by photosynthesis, although a very small amount comes from bioelectrogenesis in wetlands, and mineral electron donors in hydrothermal vents and hot springs. These trophic levels are not binary, but form a gradient that includes complete autotrophs, which obtain their sole source of carbon from the atmosphere, mixotrophs, which are autotrophic organisms that partially obtain organic matter from sources other than the atmosphere, and complete heterotrophs that must feed to obtain organic matter.

<span class="mw-page-title-main">Keystone species</span> Species with a large effect on its environment

A keystone species is a species that has a disproportionately large effect on its natural environment relative to its abundance, a concept introduced in 1969 by the zoologist Robert T. Paine. Keystone species play a critical role in maintaining the structure of an ecological community, affecting many other organisms in an ecosystem and helping to determine the types and numbers of various other species in the community. Without keystone species, the ecosystem would be dramatically different or cease to exist altogether. Some keystone species, such as the wolf, are also apex predators.

<span class="mw-page-title-main">Energy flow (ecology)</span> Flow of energy through food chains in ecological energetics

Energy flow is the flow of energy through living things within an ecosystem. All living organisms can be organized into producers and consumers, and those producers and consumers can further be organized into a food chain. Each of the levels within the food chain is a trophic level. In order to more efficiently show the quantity of organisms at each trophic level, these food chains are then organized into trophic pyramids. The arrows in the food chain show that the energy flow is unidirectional, with the head of an arrow indicating the direction of energy flow; energy is lost as heat at each step along the way.

<span class="mw-page-title-main">Scavenger</span> Organism that feeds on dead animal and/or plants material

Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding behavior. Scavengers play an important role in the ecosystem by consuming dead animal and plant material. Decomposers and detritivores complete this process, by consuming the remains left by scavengers.

Trophic cascades are powerful indirect interactions that can control entire ecosystems, occurring when a trophic level in a food web is suppressed. For example, a top-down cascade will occur if predators are effective enough in predation to reduce the abundance, or alter the behavior of their prey, thereby releasing the next lower trophic level from predation.

<span class="mw-page-title-main">Community (ecology)</span> Associated populations of species in a given area

In ecology, a community is a group or association of populations of two or more different species occupying the same geographical area at the same time, also known as a biocoenosis, biotic community, biological community, ecological community, or life assemblage. The term community has a variety of uses. In its simplest form it refers to groups of organisms in a specific place or time, for example, "the fish community of Lake Ontario before industrialization".

<span class="mw-page-title-main">Mesopredator release hypothesis</span> Ecological theory

The mesopredator release hypothesis is an ecological theory used to describe the interrelated population dynamics between apex predators and mesopredators within an ecosystem, such that a collapsing population of the former results in dramatically increased populations of the latter. This hypothesis describes the phenomenon of trophic cascade in specific terrestrial communities.

<span class="mw-page-title-main">Trophic level</span> Position of an organism in a food chain

The trophic level of an organism is the position it occupies in a food web. A food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the number of steps it is from the start of the chain. A food web starts at trophic level 1 with primary producers such as plants, can move to herbivores at level 2, carnivores at level 3 or higher, and typically finish with apex predators at level 4 or 5. The path along the chain can form either a one-way flow or a food "web". Ecological communities with higher biodiversity form more complex trophic paths.

<span class="mw-page-title-main">Rewilding (conservation biology)</span> Restoring of wilderness environments

Rewilding is a form of ecological restoration aimed at increasing biodiversity and restoring natural processes. It differs from other forms of ecological restoration in that rewilding aspires to reduce human influence on ecosystems. It is also distinct from other forms of restoration in that, while it places emphasis on recovering geographically specific sets of ecological interactions and functions that would have maintained ecosystems prior to human influence, rewilding is open to novel or emerging ecosystems which encompass new species and new interactions.

<span class="mw-page-title-main">Mesocarnivore</span> Organism that eats mostly animal tissue

A mesocarnivore is an animal whose diet consists of 50–70% meat with the balance consisting of non-vertebrate foods which may include insects, fungi, fruits, other plant material and any food that is available to them. Mesocarnivores are from a large family group of mammalian carnivores and vary from small to medium sized, which are less than fifteen kilograms. Mesocarnivores are seen today among the Canidae, Viverridae (civets), Mustelidae, Procyonidae, Mephitidae (skunks), and Herpestidae. The red fox is also the most common of the mesocarnivores in Europe and has a high population density in the areas they reside.

<span class="mw-page-title-main">Fishing down the food web</span>

Fishing down the food web is the process whereby fisheries in a given ecosystem, "having depleted the large predatory fish on top of the food web, turn to increasingly smaller species, finally ending up with previously spurned small fish and invertebrates".

<span class="mw-page-title-main">Intraguild predation</span> Killing and sometimes eating of potential competitors

Intraguild predation, or IGP, is the killing and sometimes eating of a potential competitor of a different species. This interaction represents a combination of predation and competition, because both species rely on the same prey resources and also benefit from preying upon one another. Intraguild predation is common in nature and can be asymmetrical, in which one species feeds upon the other, or symmetrical, in which both species prey upon each other. Because the dominant intraguild predator gains the dual benefits of feeding and eliminating a potential competitor, IGP interactions can have considerable effects on the structure of ecological communities.

<span class="mw-page-title-main">William J. Ripple</span>

William J. Ripple is a professor of ecology at Oregon State University in the Department of Forest Ecosystems and Society. He is best known for his research on terrestrial trophic cascades, particularly the role of the gray wolf in North America as an apex predator and a keystone species that shapes food webs and landscape structures via “top-down” pressures.

<span class="mw-page-title-main">Grizzly bear</span> Subspecies of brown bear

The grizzly bear, also known as the North American brown bear or simply grizzly, is a population or subspecies of the brown bear inhabiting North America.

<span class="mw-page-title-main">Mesopredator</span> Predator that is preyed upon

A Mesopredator is a predator that occupies a mid-ranking trophic level in a food web. There is no standard definition of a mesopredator, but mesopredators are usually medium-sized carnivorous or omnivorous animals, such as raccoons, foxes, or coyotes. They are often defined by contrast from apex predators or prey in a particular food web. Mesopredators typically prey on smaller animals.

<span class="mw-page-title-main">Marine food web</span> Marine consumer-resource system

Compared to terrestrial environments, marine environments have biomass pyramids which are inverted at the base. In particular, the biomass of consumers is larger than the biomass of primary producers. This happens because the ocean's primary producers are tiny phytoplankton which grow and reproduce rapidly, so a small mass can have a fast rate of primary production. In contrast, many significant terrestrial primary producers, such as mature forests, grow and reproduce slowly, so a much larger mass is needed to achieve the same rate of primary production.

<span class="mw-page-title-main">Ecology of fear</span> Psychological impact induced by predators

The ecology of fear is a conceptual framework describing the psychological impact that predator-induced stress experienced by animals has on populations and ecosystems. Within ecology, the impact of predators has been traditionally viewed as limited to the animals that they directly kill, while the ecology of fear advances evidence that predators may have a far more substantial impact on the individuals that they predate, reducing fecundity, survival and population sizes. To avoid being killed, animals that are preyed upon will employ anti-predator defenses which aid survival but may carry substantial costs.

References

  1. ↑ Ordiz, Andrés; Bischof, Richard; Swenson, Jon E. (2013). "Saving large carnivores, but losing the apex predator?". Biological Conservation. 168: 128–133. doi: 10.1016/j.biocon.2013.09.024 . hdl: 11250/2492589 .
  2. ↑ Kristoffer T. Everatt; Jennifer F. Moore; Graham I.H. Kerley (2019). "Africa's apex predator, the lion, is limited by interference and exploitive competition with humans". Global Ecology and Conservation. 20: e00758. doi: 10.1016/j.gecco.2019.e00758 . ISSN   2351-9894. S2CID   202023472.
  3. ↑ Whiting, Frances. "Terri fights to halt croc eggs harvest." Archived 2010-10-28 at the Wayback Machine Australia Zoo. 2007-06-11. Retrieved 2010-01-25.
  4. ↑ "Saltwater Crocodile." Archived 2013-09-06 at the Wayback Machine National Geographic. Retrieved 2010-01-25.
  5. ↑ Sukhdeo, Michael V. K. (2012). "Where are the parasites in food webs?". Parasites & Vectors. 5 (1): 239. doi: 10.1186/1756-3305-5-239 . PMC   3523981 . PMID   23092160.
  6. ↑ "predator". Online Etymological Dictionary. Archived from the original on 2009-07-01. Retrieved 2010-01-25.
  7. ↑ "apex predator". PBS. Archived from the original on 2009-07-22. Retrieved 2010-01-25.
  8. ↑ Leat, Eliza H. K.; Bourgeon, Sophie; Eze, Jude I.; Muir, Derek C.G.; Williamson, Mary; Bustnes, Jan O.; Furness, Robert W.; Borgå, Katrine (2013-02-15). "Perfluoroalkyl substances in eggs and plasma of an avian top predator, great skua (Stercorarius skua), in the north Atlantic". Environmental Toxicology and Chemistry. 32 (3): 569–576. doi: 10.1002/etc.2101 . PMID   23258709.
  9. ↑ Lepak, Jesse M.; Kraft, Clifford E.; Weidel, Brian C. (March 2006). "Rapid food web recovery in response to removal of an introduced apex predator" (PDF). Canadian Journal of Fisheries and Aquatic Sciences. 63 (3): 569–575. doi:10.1139/f05-248. Archived from the original (PDF) on 11 September 2008.
  10. ↑ Trewby, Iain D.; Young, Richard; McDonald, Robbie A.; Wilson, Gavin J.; Davison, John; Walker, Neil; Robertson, Andrew; Doncaster, C. Patrick; Delahay, Richard J. (April 2014). Criscuolo, François (ed.). "Impacts of Removing Badgers on Localised Counts of Hedgehogs". PLOS ONE. 9 (4): e95477. Bibcode:2014PLoSO...995477T. doi: 10.1371/journal.pone.0095477 . PMC   3988185 . PMID   24736454.
  11. ↑ Davic, Robert D. (2003). "Linking Keystone Species and Functional Groups: A New Operational Definition of the Keystone Species Concept". Conservation Ecology. 7. doi:10.5751/ES-00502-0701r11. hdl: 10535/2966 . Retrieved 2011-02-03.
  12. ↑ Wallach, Arian D.; Izhaki, Ido; Toms, Judith D.; Ripple, William J.; Shanas, Uri (2015). "What is an apex predator?". Oikos. 124 (11): 1453–1461. doi: 10.1111/oik.01977 .
  13. ↑ Stier, A. C.; Samhouri, J. F.; Novak, M.; Marshall, K. N.; Ward, E. J.; Holt, R. D.; Levin, P. S. (May 2016). "Ecosystem context and historical contingency in apex predator recoveries". Science Advances. 2 (5): e1501769. Bibcode:2016SciA....2E1769S. doi:10.1126/sciadv.1501769. PMC   4928970 . PMID   27386535.
  14. ↑ Croll, D. A.; Maron, J. L.; et al. (March 2005). "Introduced predators transform subarctic islands from grassland to tundra". Science . 307 (5717): 1959–1961. Bibcode:2005Sci...307.1959C. doi:10.1126/science.1108485. PMID   15790855. S2CID   19305264.
  15. ↑ Egan, Logan Zane; Téllez, Jesús Javier (June 2005). "Effects of preferential primary consumer fishing on lower trophic level herbivores in the Line Islands" (PDF). Stanford at Sea. Stanford University. Archived (PDF) from the original on 2010-07-12. Retrieved 2010-01-25.
  16. ↑ Pace, M. L.; Cole, J. J.; et al. (December 1999). "Trophic cascades revealed in diverse ecosystems". Trends in Ecology and Evolution. 14 (12): 483–488. doi:10.1016/S0169-5347(99)01723-1. PMID   10542455.
  17. ↑ Berger, Joel (1999). "Anthropogenic extinction of top carnivores and interspecific animal behaviour: implications of the rapid decoupling of a web involving wolves, bears, moose and ravens" (PDF). Proceedings of the Royal Society B: Biological Sciences. 266 (1435): 2261–2267. doi:10.1098/rspb.1999.0917. PMC   1690453 . PMID   10629976.
  18. ↑ Baum, Julia K.; Worm, Boris (2009). "Cascading top-down effects of changing oceanic predator abundances". Journal of Animal Ecology. 78 (4): 699–714. doi: 10.1111/j.1365-2656.2009.01531.x . PMID   19298616.
  19. ↑ Soulé, Michael E.; Bolger, Douglas T.; Alberts, Allison C.; Wright, John; Sorice, Marina; Hill, Scott (March 1988). "Reconstructed Dynamics of Rapid Extinctions of Chaparral-Requiring Birds in Urban Habitat Islands" (PDF). Conservation Biology. 2 (1): 75–92. doi:10.1111/j.1523-1739.1988.tb00337.x. hdl: 2027.42/74761 .
  20. ↑ Prugh, Laura R.; Stoner, Chantal J.; Epps, Clinton W.; Bean, William T.; Ripple, William J.; Laliberte, Andrea S.; Brashares, Justin S. (2009). "The Rise of the Mesopredator". BioScience. 59 (9): 779–791. doi:10.1525/bio.2009.59.9.9. S2CID   40484905.
  21. ↑ Estes, James A.; Terborgh, John; Brashares, Justin S.; Power, Mary E.; Berger, Joel; Bond, William J.; et al. (2011). "Trophic Downgrading of Planet Earth". Science. 333 (6040): 301–306. Bibcode:2011Sci...333..301E. CiteSeerX   10.1.1.701.8043 . doi:10.1126/science.1205106. PMID   21764740. S2CID   7752940.
  22. ↑ Silliman, Brian R.; Hughes, Brent B.; Gaskins, Leo C.; He, Qiang; Tinker, M. Tim; Read, Andrew; Nifong, James; Stepp, Rick (2018). "Are the ghosts of nature's past haunting ecology today?". Current Biology. 28 (9): R532–R537. doi: 10.1016/j.cub.2018.04.002 . PMID   29738721.
  23. ↑ "Climate impacts on polar bears". Polar Bear Specialist Group. 27 January 2009. Retrieved 9 September 2018.
  24. ↑ Lister, Brad & McDaniel, Carl. "The wolves of Yellowstone" Archived 2011-07-20 at the Wayback Machine (2006-04-17), p. 2. Retrieved 2010-01-25.
  25. ↑ Levy, Sharon (November 2002). "Top Dogs". Archived from the original on 2009-06-06. Retrieved 2010-01-25.
  26. ↑ Wilmers, Christopher C. (2004). "The gray wolf – scavenger complex in Yellowstone National Park" (PDF). pp. 56, 90 and throughout. Archived (PDF) from the original on 2010-07-12. Retrieved 2010-01-25.
  27. ↑ Robbins, Jim (May–June 1998). "Weaving a new web: wolves change an ecosystem". Smithsonian Zoogoer. Smithsonian Institution. 27 (3). Archived from the original on 10 February 2010. Retrieved 2010-01-25.
  28. ↑ Dobson, Andy P.; Wilmers, Christopher C; Getz, Wayne M. (2005). "Gray Wolves as Climate Change Buffers in Yellowstone". PLOS Biology. 3 (4): e92. doi: 10.1371/journal.pbio.0030092 . PMC   1064850 . PMID   15757363.
  29. ↑ Bonhommeau, S.; Dubroca, L.; Le Pape, O.; Barde, J.; Kaplan, D. M.; Chassot, E.; Nieblas, A.-E. (2013). "Eating up the world's food web and the human trophic level". Proceedings of the National Academy of Sciences. 110 (51): 20617–20620. Bibcode:2013PNAS..11020617B. doi: 10.1073/pnas.1305827110 . PMC   3870703 . PMID   24297882.
  30. 1 2 Roopnarine, Peter D. (2014). "Humans are apex predators". Proceedings of the National Academy of Sciences. 111 (9): E796. Bibcode:2014PNAS..111E.796R. doi: 10.1073/pnas.1323645111 . PMC   3948303 . PMID   24497513.
  31. ↑ Ben-Dor, Miki; Sirtoli, Raphael; Barkai, Ran (2021). "The evolution of the human trophic level during the Pleistocene". American Journal of Physical Anthropology . 175: 27–56. doi: 10.1002/ajpa.24247 . PMID   33675083.
  32. 1 2 Callaway, Ewen (2011). "Cambrian super-predators grew large in arms race". Nature. doi:10.1038/news.2011.318.
  33. ↑ Zanno, Lindsay E.; Makovicky, Peter J. (22 November 2013). "Neovenatorid theropods are apex predators in the Late Cretaceous of North America". Nature Communications. 4 (1): 2827. Bibcode:2013NatCo...4.2827Z. doi: 10.1038/ncomms3827 . PMID   24264527.
  34. ↑ Van Valkenburgh, Blaire; Molnar, Ralph E. (2002). "Dinosaurian and Mammalian Predators Compared". Paleobiology. 28 (4): 527–543. doi:10.1666/0094-8373(2002)028<0527:DAMPC>2.0.CO;2. JSTOR   3595499. S2CID   85725299.
  35. ↑ Kriwet, J.; Witzmann, F.; Klug, S.; Heidtke, U. H.J (2008). "First direct evidence of a vertebrate three-level trophic chain in the fossil record". Proceedings of the Royal Society B: Biological Sciences. 275 (1631): 181–186. doi:10.1098/rspb.2007.1170. PMC   2596183 . PMID   17971323.
  36. ↑ Werdelin, Lars; McDonald, H. G.; Shaw, Christopher A. (2018). Smilodon: The Iconic Sabertooth. Johns Hopkins University Press. p. 204. ISBN   978-1-4214-2556-6.
  37. ↑ McKie, Robin (1 March 2015). "How hunting with wolves helped humans outsmart the Neanderthals". The Guardian . Retrieved 14 October 2018.
  38. ↑ Shipman, Pat (2015). The invaders : how humans and their dogs drove Neanderthals to extinction. Harvard University Press. ISBN   978-0-674-73676-4. OCLC   893897294.
  39. ↑ "The 7 categories of dog" . The Daily Telegraph. 10 March 2017. Archived from the original on 2022-01-11.
  40. ↑ "Portuguese Water Dog". The Kennel Club . Retrieved 14 October 2018.
  41. ↑ Fergus, Charles (2002). Gun Dog Breeds, A Guide to Spaniels, Retrievers, and Pointing Dogs. The Lyons Press. ISBN   978-1-58574-618-7.
  42. ↑ "History of Falconry". The Falconry Centre. Archived from the original on 29 May 2016. Retrieved 22 April 2016.
  43. ↑ Rudstam, Lars G.; VanDeValk, Anthony J. (February 2004). "Cormorant Predation and the Population Dynamics of Walleye and Yellow Perch in Oneida Lake". Ecological Applications. 14 (1): 149–163. doi:10.1890/03-5010. JSTOR   4493527. providing the opportunity to study the effects of an increase of a top predator on an existing predator-prey system
  44. ↑ King, Richard J. (2013). The Devil's Cormorant: A Natural History. University of New Hampshire Press. p. 9. ISBN   978-1-61168-225-0.
  45. 1 2 3 4 Hammerschlag, Neil; Gallagher, Austin J.; Wester, Julia; Luo, Jiangang; Ault, Jerald S. (2012). "Don't bite the hand that feeds: assessing ecological impacts of provisioning ecotourism on an apex marine predator". Functional Ecology. 26 (3): 567–576. doi: 10.1111/j.1365-2435.2012.01973.x .
  46. 1 2 Macdonald, Catherine; Gallagher, Austin J.; Barnett, Adam; Brunnschweiler, Juerg; Shiffman, David S.; Hammerschlag, Neil (2017). "Conservation potential of apex predator tourism". Biological Conservation. 215: 132–141. doi:10.1016/j.biocon.2017.07.013.
  47. ↑ Jones, Lucy. "The rewilding plan that would return Britain to nature". BBC. Retrieved 6 June 2018. wolves, bears and lynx roamed the land. ... Humans chopped down the trees to make space for farms, and hunted the large animals to extinction, leaving plant-eaters to decimate the country's flora. Britain is now one of the few countries in the world that doesn't have top predators.
  48. 1 2 3 Lister, Paul (28 April 2015). "Bring on a few more apex predators" . The Daily Telegraph. Archived from the original on 2022-01-11. Retrieved 14 March 2018.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.