87-511: An apex predator , also known as a top predator or superpredator , is a predator at the top of a food chain , without natural predators of its own. 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
174-455: A mutation (the deletion of two nucleotides ) that inactives it. These changes are explained by the fact that its prey does not need to be subdued. Several groups of predatory fish have the ability to detect, track, and sometimes, as in the electric ray , to incapacitate their prey by sensing and generating electric fields . The electric organ is derived from modified nerve or muscle tissue. Physiological adaptations to predation include
261-562: 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 . 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
348-540: A Greater Yellowstone Coalition leader enlarged that to 20,000,000 acres (80,000 km ). In 1985 the United States House of Representatives Subcommittees on Public Lands and National Parks and Recreation held a joint subcommittee hearing on Greater Yellowstone, resulting in a 1986 report by the Congressional Research Service outlining shortcomings in inter-agency coordination and concluding that
435-418: A better choice. If it chooses pursuit, its physical capabilities determine the mode of pursuit (e.g., ambush or chase). Having captured the prey, it may also need to expend energy handling it (e.g., killing it, removing any shell or spines, and ingesting it). Predators have a choice of search modes ranging from sit-and-wait to active or widely foraging . The sit-and-wait method is most suitable if
522-851: A broad range of taxa including arthropods. They are common among insects, including mantids, dragonflies , lacewings and scorpionflies . In some species such as the alderfly , only the larvae are predatory (the adults do not eat). Spiders are predatory, as well as other terrestrial invertebrates such as scorpions ; centipedes ; some mites , snails and slugs ; nematodes ; and planarian worms . In marine environments, most cnidarians (e.g., jellyfish , hydroids ), ctenophora (comb jellies), echinoderms (e.g., sea stars , sea urchins , sand dollars , and sea cucumbers ) and flatworms are predatory. Among crustaceans , lobsters , crabs , shrimps and barnacles are predators, and in turn crustaceans are preyed on by nearly all cephalopods (including octopuses , squid and cuttlefish ). Seed predation
609-559: 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. Carnivorous theropod dinosaurs including Allosaurus and Tyrannosaurus are theorized to have been apex predators, based on their size, morphology, and dietary needs. A Permian shark, Triodus sessilis ,
696-409: A flagship site among conservation groups that promote ecosystem management . The Greater Yellowstone Ecosystem (GYE) is one of the world's foremost natural laboratories in landscape ecology and Holocene geology , and is a world-renowned recreational destination. It is also home to the diverse native plants and animals of Yellowstone . Yellowstone National Park boundaries were drawn in 1872 with
783-582: A food trap, mechanical stimulation, and electrical impulses to eventually catch and consume its prey. Some carnivorous fungi catch nematodes using either active traps in the form of constricting rings, or passive traps with adhesive structures. Many species of protozoa ( eukaryotes ) and bacteria ( prokaryotes ) prey on other microorganisms; the feeding mode is evidently ancient, and evolved many times in both groups. Among freshwater and marine zooplankton , whether single-celled or multi-cellular, predatory grazing on phytoplankton and smaller zooplankton
870-405: A good long-term data set on the species, but they understand its ecology well enough to project declining future conservation status . A more immediate and serious threat to whitebark pines is an introduced fungal rust disease, White Pine Blister Rust ( Cronartium ribicola ), which is causing heavy mortality in the species. Occasional resistant individuals occur, but in the short to medium term,
957-471: A huge gulp of water and filtering it through their feathery baleen plates. Pursuit predators may be social , like the lion and wolf that hunt in groups, or solitary. Once the predator has captured the prey, it has to handle it: very carefully if the prey is dangerous to eat, such as if it possesses sharp or poisonous spines, as in many prey fish. Some catfish such as the Ictaluridae have spines on
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#17330860437811044-473: A key component of the ecosystem, providing sustenance for predators. Other significant ungulate species include moose (Alces alces), pronghorn (Antilocapra americana), bighorn sheep (Ovis canadensis), and mountain goats (Oreamnos americanus). The GYE is home to a variety of birds, including iconic species like Bald Eagles , Golden Eagles and Peregrine Falcons . Osprey populations around Yellowstone Lake , have experienced declines, linked to
1131-725: A kill, and the coyote can be either solitary or social. Other solitary predators include the northern pike, wolf spiders and all the thousands of species of solitary wasps among arthropods, and many microorganisms and zooplankton . Under the pressure of natural selection , predators have evolved a variety of physical adaptations for detecting, catching, killing, and digesting prey. These include speed, agility, stealth, sharp senses, claws, teeth, filters, and suitable digestive systems. For detecting prey , predators have well-developed vision , smell , or hearing . Predators as diverse as owls and jumping spiders have forward-facing eyes, providing accurate binocular vision over
1218-615: 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. 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
1305-539: A long distance, sometimes for hours at a time. The method is used by human hunter-gatherers and by canids such as African wild dogs and domestic hounds. The African wild dog is an extreme persistence predator, tiring out individual prey by following them for many miles at relatively low speed. A specialised form of pursuit predation is the lunge feeding of baleen whales . These very large marine predators feed on plankton , especially krill , diving and actively swimming into concentrations of plankton, and then taking
1392-502: A minimum estimate of 236, but biologists think there may be as many as 1,000 bears in the ecosystem. Although the Greater Yellowstone population is relatively close to recovery goals, the plan's definition of recovery is controversial. Thus, even though the population may be stable or possibly increasing in the short term, in the longer term, continued habitat loss , climate change, and increasing human activities may well reverse
1479-445: A patch and decide whether to spend time searching for prey in it. This may involve some knowledge of the preferences of the prey; for example, ladybirds can choose a patch of vegetation suitable for their aphid prey. To capture prey, predators have a spectrum of pursuit modes that range from overt chase ( pursuit predation ) to a sudden strike on nearby prey ( ambush predation ). Another strategy in between ambush and pursuit
1566-491: A population may be considered long-term by some, one of the important lessons of Greater Yellowstone management is that even half a century is not long enough to give a full idea of how a species may vary in its occupation of a wild ecosystem. The Yellowstone hot springs are important for their diversity of thermophilic bacteria. These bacteria have been useful in studies of the evolution of photosynthesis and as sources of thermostable enzymes for molecular biology . Although
1653-425: A powerful selective effect on prey, and the prey develop antipredator adaptations such as warning coloration , alarm calls and other signals , camouflage , mimicry of well-defended species, and defensive spines and chemicals. Sometimes predator and prey find themselves in an evolutionary arms race , a cycle of adaptations and counter-adaptations. Predation has been a major driver of evolution since at least
1740-785: A predator, while small prey might prove hard to find and in any case provide less of a reward. This has led to a correlation between the size of predators and their prey. Size may also act as a refuge for large prey. For example, adult elephants are relatively safe from predation by lions, but juveniles are vulnerable. Members of the cat family such as the snow leopard (treeless highlands), tiger (grassy plains, reed swamps), ocelot (forest), fishing cat (waterside thickets), and lion (open plains) are camouflaged with coloration and disruptive patterns suiting their habitats. In aggressive mimicry , certain predators, including insects and fishes, make use of coloration and behaviour to attract prey. Female Photuris fireflies , for example, copy
1827-421: A preferred target is scarce. When prey have a clumped (uneven) distribution, the optimal strategy for the predator is predicted to be more specialized as the prey are more conspicuous and can be found more quickly; this appears to be correct for predators of immobile prey, but is doubtful with mobile prey. In size-selective predation, predators select prey of a certain size. Large prey may prove troublesome for
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#17330860437811914-522: 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). 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
2001-820: A relatively narrow field of view, whereas prey animals often have less acute all-round vision. Animals such as foxes can smell their prey even when it is concealed under 2 feet (60 cm) of snow or earth. Many predators have acute hearing, and some such as echolocating bats hunt exclusively by active or passive use of sound. Predators including big cats , birds of prey , and ants share powerful jaws, sharp teeth, or claws which they use to seize and kill their prey. Some predators such as snakes and fish-eating birds like herons and cormorants swallow their prey whole; some snakes can unhinge their jaws to allow them to swallow large prey, while fish-eating birds have long spear-like beaks that they use to stab and grip fast-moving and slippery prey. Fish and other predators have developed
2088-408: A severe population decline is expected. Estimates of the decline of quaking aspen ( Populus tremuloides ) on the park's northern range since 1872 range from 50% to 95%. The decline has been linked to multiple stressors, such as defoliation by the forest tent caterpillar ( Malacosoma disstria ), aspen bark beetles ( Trypophloeus populi and Procryphalus mucronatus ), wood-boring beetles such as
2175-478: A significant amount of energy, to locate each food patch. For example, the black-browed albatross regularly makes foraging flights to a range of around 700 kilometres (430 miles), up to a maximum foraging range of 3,000 kilometres (1,860 miles) for breeding birds gathering food for their young. With static prey, some predators can learn suitable patch locations and return to them at intervals to feed. The optimal foraging strategy for search has been modelled using
2262-575: A significant area of petrified trees; the northeast corner was defined by the watershed of Pebble Creek; the eastern boundary included the headwaters of the Lamar River and part of the watershed of the Yellowstone River. In 1932, President Hoover issued an executive order that added more than 7,000 acres (2,800 ha) between the north boundary and the Yellowstone River, west of Gardiner. These lands provided winter range for elk and other ungulates. By
2349-480: A significant management achievement, does not begin to restore the species' historical abundance. Also, they declined because of invasive lake trout. An aggressive lake trout removal program has caused the cutthroats to rebound. Early accounts of pronghorn ( Antilocapra americana ) in Greater Yellowstone described herds of hundreds seen ranging through most major river valleys . These populations were decimated by 1900, and declines continued among remaining herds. On
2436-406: A small animal, gulping the prey in an extremely rapid movement when it is within range. Many smaller predators such as the box jellyfish use venom to subdue their prey, and venom can also aid in digestion (as is the case for rattlesnakes and some spiders ). The marbled sea snake that has adapted to egg predation has atrophied venom glands, and the gene for its three finger toxin contains
2523-523: A smaller area. For example, when mixed flocks of birds forage, the birds in front flush out insects that are caught by the birds behind. Spinner dolphins form a circle around a school of fish and move inwards, concentrating the fish by a factor of 200. By hunting socially chimpanzees can catch colobus monkeys that would readily escape an individual hunter, while cooperating Harris hawks can trap rabbits. Predators of different species sometimes cooperate to catch prey. In coral reefs , when fish such as
2610-440: A variety of defences including the ability to hear the echolocation calls. Many pursuit predators that run on land, such as wolves, have evolved long limbs in response to the increased speed of their prey. Their adaptations have been characterized as an evolutionary arms race , an example of the coevolution of two species. In a gene centered view of evolution , the genes of predator and prey can be thought of as competing for
2697-477: Is ballistic interception , where a predator observes and predicts a prey's motion and then launches its attack accordingly. Ambush or sit-and-wait predators are carnivorous animals that capture prey by stealth or surprise. In animals, ambush predation is characterized by the predator's scanning the environment from a concealed position until a prey is spotted, and then rapidly executing a fixed surprise attack. Vertebrate ambush predators include frogs, fish such as
Apex predator - Misplaced Pages Continue
2784-609: 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 other 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
2871-494: Is common, and found in many species of nanoflagellates , dinoflagellates , ciliates , rotifers , a diverse range of meroplankton animal larvae, and two groups of crustaceans, namely copepods and cladocerans . To feed, a predator must search for, pursue and kill its prey. These actions form a foraging cycle. The predator must decide where to look for prey based on its geographical distribution; and once it has located prey, it must assess whether to pursue it or to wait for
2958-629: Is detected, the predator assesses whether to attack it. This may involve ambush or pursuit predation , sometimes after stalking the prey. If the attack is successful, the predator kills the prey, removes any inedible parts like the shell or spines, and eats it. Predators are adapted and often highly specialized for hunting, with acute senses such as vision , hearing , or smell . Many predatory animals , both vertebrate and invertebrate , have sharp claws or jaws to grip, kill, and cut up their prey. Other adaptations include stealth and aggressive mimicry that improve hunting efficiency. Predation has
3045-507: Is one of the last remaining large, nearly intact ecosystems in the northern temperate zone of the Earth . It is located within the northern Rocky Mountains , in areas of northwestern Wyoming , southwestern Montana , and eastern Idaho , and is about 22 million acres (89,000 km ). Yellowstone National Park and the Yellowstone Caldera 'hotspot' are within it. The area is
3132-514: Is restricted to mammals, birds, and insects but is found in almost all terrestrial ecosystems. Egg predation includes both specialist egg predators such as some colubrid snakes and generalists such as foxes and badgers that opportunistically take eggs when they find them. Some plants, like the pitcher plant , the Venus fly trap and the sundew , are carnivorous and consume insects . Methods of predation by plants varies greatly but often involves
3219-809: Is shrinking the sea ice of the Arctic, forcing polar bears to fast on land for increasingly long periods. 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. In addition to their effect on prey species,
3306-430: Is size. Prey that is too small may not be worth the trouble for the amount of energy it provides. Too large, and it may be too difficult to capture. For example, a mantid captures prey with its forelegs and they are optimized for grabbing prey of a certain size. Mantids are reluctant to attack prey that is far from that size. There is a positive correlation between the size of a predator and its prey. A predator may assess
3393-401: The Cambrian period. At the most basic level, predators kill and eat other organisms. However, the concept of predation is broad, defined differently in different contexts, and includes a wide variety of feeding methods; moreover, some relationships that result in the prey's death are not necessarily called predation. A parasitoid , such as an ichneumon wasp , lays its eggs in or on its host;
3480-465: The angel shark , the northern pike and the eastern frogfish . Among the many invertebrate ambush predators are trapdoor spiders and Australian Crab spiders on land and mantis shrimps in the sea. Ambush predators often construct a burrow in which to hide, improving concealment at the cost of reducing their field of vision. Some ambush predators also use lures to attract prey within striking range. The capturing movement has to be rapid to trap
3567-455: The common garter snake has developed a resistance to the toxin in the skin of the rough-skinned newt . Predators affect their ecosystems not only directly by eating their own prey, but by indirect means such as reducing predation by other species, or altering the foraging behaviour of a herbivore, as with the biodiversity effect of wolves on riverside vegetation or sea otters on kelp forests. This may explain population dynamics effects such as
Apex predator - Misplaced Pages Continue
3654-475: The grouper and coral trout spot prey that is inaccessible to them, they signal to giant moray eels , Napoleon wrasses or octopuses . These predators are able to access small crevices and flush out the prey. Killer whales have been known to help whalers hunt baleen whales . Social hunting allows predators to tackle a wider range of prey, but at the risk of competition for the captured food. Solitary predators have more chance of eating what they catch, at
3741-461: The marginal value theorem . Search patterns often appear random. One such is the Lévy walk , that tends to involve clusters of short steps with occasional long steps. It is a good fit to the behaviour of a wide variety of organisms including bacteria, honeybees, sharks and human hunter-gatherers. Having found prey, a predator must decide whether to pursue it or keep searching. The decision depends on
3828-466: The poplar borer ( Saperda calcarata ) and the bronze poplar borer ( Agrilus liragus ), fungal disturbances such as those by the Cytospora canker ( Valsa sordida ), and Climate change related stressors. Anecdotal information on grizzly bear abundance dates to the mid-19th century, and administrators have made informal population estimates for more than 70 years. From these sources, ecologists know
3915-471: The tiger shark , and through rewilding efforts, such as the proposed reintroduction of the Iberian lynx . 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
4002-400: The 1970s, the grizzly bear 's ( Ursus arctos ) range in and near the park became the first informal minimum boundary of a theoretical "Greater Yellowstone Ecosystem" that included at least 4,000,000 acres (16,000 km ). Since then, definitions of the greater ecosystem's size have steadily grown larger. A 1994 study listed the size as 19,000,000 acres (76,890 km ), while a 1994 speech by
4089-537: The Greater Yellowstone Ecosystem. The GYE is home to some of North America's most iconic wildlife. The ecosystem supports the largest free-roaming herds of American bison (Bison bison) on public land, a species central to the region's ecological balance. Grizzly bears (Ursus arctos horribilis) and gray wolves (Canis lupus) are apex predators that play crucial roles in regulating prey populations. Elk (Cervus canadensis) are abundant and form
4176-709: The ability of predatory bacteria to digest the complex peptidoglycan polymer from the cell walls of the bacteria that they prey upon. Carnivorous vertebrates of all five major classes (fishes, amphibians, reptiles, birds, and mammals) have lower relative rates of sugar to amino acid transport than either herbivores or omnivores, presumably because they acquire plenty of amino acids from the animal proteins in their diet. To counter predation, prey have evolved defences for use at each stage of an attack. They can try to avoid detection, such as by using camouflage and mimicry . They can detect predators and warn others of their presence. If detected, they can try to avoid being
4263-728: The ability to crush or open the armoured shells of molluscs. Many predators are powerfully built and can catch and kill animals larger than themselves; this applies as much to small predators such as ants and shrews as to big and visibly muscular carnivores like the cougar and lion . Predators are often highly specialized in their diet and hunting behaviour; for example, the Eurasian lynx only hunts small ungulates . Others such as leopards are more opportunistic generalists, preying on at least 100 species. The specialists may be highly adapted to capturing their preferred prey, whereas generalists may be better able to switch to other prey when
4350-591: The area's essential values were at risk. Federally managed areas within the GYE include: Ten distinct National Wilderness Areas have been established within the GYE's National Forests since 1966, mandating a higher level of habitat protection than the USFS otherwise uses. The GYE also encompasses some privately held and state lands surrounding those managed by the U.S. Government. The Trust for Public Land has protected 67,000 acres (27,000 ha) over about 40 projects in
4437-584: The assault. When animals eat seeds ( seed predation or granivory ) or eggs ( egg predation ), they are consuming entire living organisms, which by definition makes them predators. Scavengers , organisms that only eat organisms found already dead, are not predators, but many predators such as the jackal and the hyena scavenge when the opportunity arises. Among invertebrates, social wasps such as yellowjackets are both hunters and scavengers of other insects. While examples of predators among mammals and birds are well known, predators can be found in
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#17330860437814524-684: The back (dorsal) and belly (pectoral) which lock in the erect position; as the catfish thrashes about when captured, these could pierce the predator's mouth, possibly fatally. Some fish-eating birds like the osprey avoid the danger of spines by tearing up their prey before eating it. In social predation, a group of predators cooperates to kill prey. This makes it possible to kill creatures larger than those they could overpower singly; for example, hyenas , and wolves collaborate to catch and kill herbivores as large as buffalo, and lions even hunt elephants. It can also make prey more readily available through strategies like flushing of prey and herding it into
4611-590: The consequences of both controlling prey density and restricting smaller predators, and may be capable of self-regulation. They are central to the functioning of ecosystems, the regulation of disease, and the maintenance of biodiversity. When introduced to subarctic islands, for example, Arctic foxes ' predation of seabirds has been shown to turn grassland into the tundra . 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. For example,
4698-416: The costs and benefits involved. A bird foraging for insects spends a lot of time searching but capturing and eating them is quick and easy, so the efficient strategy for the bird is to eat every palatable insect it finds. By contrast, a predator such as a lion or falcon finds its prey easily but capturing it requires a lot of effort. In that case, the predator is more selective. One of the factors to consider
4785-536: The counties of Norfolk , Cumbria , and Northumberland in England, and Aberdeenshire in Scotland as part of the rewilding movement. The reintroduction of large predators is controversial, in part because of concern among farmers for their livestock . 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
4872-705: The cycles observed in lynx and snowshoe hares. One way of classifying predators is by trophic level . Carnivores that feed on herbivores are secondary consumers; their predators are tertiary consumers, and so forth. At the top of this food chain are apex predators such as lions . Many predators however eat from multiple levels of the food chain; a carnivore may eat both secondary and tertiary consumers. This means that many predators must contend with intraguild predation , where other predators kill and eat them. For example, coyotes compete with and sometimes kill gray foxes and bobcats . Greater Yellowstone Ecosystem The Greater Yellowstone Ecosystem (GYE)
4959-519: The decrease in Cutthroat Trout. Several bird species act as keystone species within the GYE. For example, the Clark's Nutcracker plays a crucial role in the dispersal of the all-important Whitebark Pine seeds. Ecological management has been most often advanced through concerns over individual species rather than over broader ecological principles. Though 20 or 30 or even 50 years of information on
5046-993: The eggs hatch into larvae, which eat the host, and it inevitably dies. Zoologists generally call this a form of parasitism , though conventionally parasites are thought not to kill their hosts. A predator can be defined to differ from a parasitoid in that it has many prey, captured over its lifetime, where a parasitoid's larva has just one, or at least has its food supply provisioned for it on just one occasion. There are other difficult and borderline cases. Micropredators are small animals that, like predators, feed entirely on other organisms; they include fleas and mosquitoes that consume blood from living animals, and aphids that consume sap from living plants. However, since they typically do not kill their hosts, they are now often thought of as parasites. Animals that graze on phytoplankton or mats of microbes are predators, as they consume and kill their food organisms, while herbivores that browse leaves are not, as their food plants usually survive
5133-404: The evolution of mimicry. Avoidance is not necessarily an evolutionary response as it is generally learned from bad experiences with prey. However, when the prey is capable of killing the predator (as can a coral snake with its venom), there is no opportunity for learning and avoidance must be inherited. Predators can also respond to dangerous prey with counter-adaptations. In western North America,
5220-954: 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 . Humans still hunt with dogs , which have often been bred as gun dogs to point to , flush out , or retrieve prey . The Portuguese Water Dog was used to drive fish into nets. Several breeds of dog have been used to chase large prey such as deer and wolves. Eagles and falcons , which are apex predators, are used in falconry , hunting birds or mammals. Tethered cormorants , also top predators, have been used to catch fish . Ecotourism sometimes relies on apex predators to attract business. 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. This in turn can have effects on predator population and therefore on
5307-475: The intent to include all the known geothermal basins in the region . As landscape ecology considerations were not incorporated into original boundary, revisions were suggested to conform more closely to natural topographic features, such as the ridgeline of the Absaroka Range along the east boundary. In 1929, President Hoover signed the first bill changing the park's boundaries: The northwest corner now included
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#17330860437815394-431: The larvae of coccinellid beetles (ladybirds) , alternate between actively searching and scanning the environment. Prey distributions are often clumped, and predators respond by looking for patches where prey is dense and then searching within patches. Where food is found in patches, such as rare shoals of fish in a nearly empty ocean, the search stage requires the predator to travel for a substantial time, and to expend
5481-429: The light signals of other species, thereby attracting male fireflies, which they capture and eat. Flower mantises are ambush predators; camouflaged as flowers, such as orchids , they attract prey and seize it when it is close enough. Frogfishes are extremely well camouflaged, and actively lure their prey to approach using an esca , a bait on the end of a rod-like appendage on the head, which they wave gently to mimic
5568-638: The objective of rewilding. Predator 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 (which usually do not kill the host ) and parasitoidism (which always does, eventually). 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. Predators may actively search for or pursue prey or wait for it, often concealed. When prey
5655-434: The other hand, the fitness cost of a given lost dinner is unpredictable, as the predator may quickly find better prey. In addition, most predators are generalists, which reduces the impact of a given prey adaption on a predator. Since specialization is caused by predator-prey coevolution, the rarity of specialists may imply that predator-prey arms races are rare. It is difficult to determine whether given adaptations are truly
5742-617: The park's northern range, pronghorn declined from 500 to 700 in the 1930s to about 122 in 1968. By 1992 the herd had increased to 536. The park is a commonly cited example of apex predators affecting an ecosystem through a trophic cascade . After the reintroduction of the gray wolf in 1995, researchers noticed drastic changes occurring. Elk , the primary prey of the gray wolf, became less abundant and changed their behavior, freeing riparian zones from constant grazing. The respite allowed willows and aspens to grow, creating habitat for beaver , moose , and scores of other species. In addition to
5829-489: The park. 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
5916-463: The past two centuries. Because apex predators have powerful effects on other predators, herbivores, and plants, they can be important in nature conservation. Humans have hunted many apex predators close to extinction, but in some parts of the world, these predators are now returning. 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
6003-538: The prey an opportunity to escape. Some frogs wait until snakes have begun their strike before jumping, reducing the time available to the snake to recalibrate its attack, and maximising the angular adjustment that the snake would need to make to intercept the frog in real time. Ballistic predators include insects such as dragonflies, and vertebrates such as archerfish (attacking with a jet of water), chameleons (attacking with their tongues), and some colubrid snakes . In pursuit predation, predators chase fleeing prey. If
6090-549: The prey are dense and mobile, and the predator has low energy requirements. Wide foraging expends more energy, and is used when prey is sedentary or sparsely distributed. There is a continuum of search modes with intervals between periods of movement ranging from seconds to months. Sharks, sunfish , Insectivorous birds and shrews are almost always moving while web-building spiders, aquatic invertebrates, praying mantises and kestrels rarely move. In between, plovers and other shorebirds , freshwater fish including crappies , and
6177-413: The prey flees in a straight line, capture depends only on the predator's being faster than the prey. If the prey manoeuvres by turning as it flees, the predator must react in real time to calculate and follow a new intercept path, such as by parallel navigation , as it closes on the prey. Many pursuit predators use camouflage to approach the prey as close as possible unobserved ( stalking ) before starting
6264-428: The prey's body. However, the "life-dinner" principle of Dawkins and Krebs predicts that this arms race is asymmetric: if a predator fails to catch its prey, it loses its dinner, while if it succeeds, the prey loses its life. The metaphor of an arms race implies ever-escalating advances in attack and defence. However, these adaptations come with a cost; for instance, longer legs have an increased risk of breaking, while
6351-433: The prey, given that the attack is not modifiable once launched. Ballistic interception is the strategy where a predator observes the movement of a prey, predicts its motion, works out an interception path, and then attacks the prey on that path. This differs from ambush predation in that the predator adjusts its attack according to how the prey is moving. Ballistic interception involves a brief period for planning, giving
6438-504: The price of increased expenditure of energy to catch it, and increased risk that the prey will escape. Ambush predators are often solitary to reduce the risk of becoming prey themselves. Of 245 terrestrial members of the Carnivora (the group that includes the cats, dogs, and bears), 177 are solitary; and 35 of the 37 wild cats are solitary, including the cougar and cheetah. However, the solitary cougar does allow other cougars to share in
6525-414: The pursuit. Pursuit predators include terrestrial mammals such as humans, African wild dogs, spotted hyenas and wolves; marine predators such as dolphins, orcas and many predatory fishes, such as tuna; predatory birds (raptors) such as falcons; and insects such as dragonflies . An extreme form of pursuit is endurance or persistence hunting , in which the predator tires out the prey by following it over
6612-470: The result of coevolution, where a prey adaptation gives rise to a predator adaptation that is countered by further adaptation in the prey. An alternative explanation is escalation , where predators are adapting to competitors, their own predators or dangerous prey. Apparent adaptations to predation may also have arisen for other reasons and then been co-opted for attack or defence. In some of the insects preyed on by bats, hearing evolved before bats appeared and
6699-495: The smell of sulfur is common and there are some sulfur fixing cyanobacteria , it has been found that hydrogen is being used as an energy source by extremophile microbes . Among native plants of the GYE, whitebark pine ( Pinus albicaulis ) is a species of special interest, in large part because of its seasonal importance to grizzly bears, but also because its distribution could be dramatically reduced by relatively minor global warming . In this case, researchers do not have
6786-417: The specialized tongue of the chameleon, with its ability to act like a projectile, is useless for lapping water, so the chameleon must drink dew off vegetation. The "life-dinner" principle has been criticized on multiple grounds. The extent of the asymmetry in natural selection depends in part on the heritability of the adaptive traits. Also, if a predator loses enough dinners, it too will lose its life. On
6873-399: The species was common in Greater Yellowstone when Europeans arrived and that the population was not isolated before the 1930s, but is now. Researchers do not know if bears were more or less common than now. A 1959-1970 bear study suggested a grizzly bear population size of about 176, later revised to about 229. Later estimates have ranged as low as 136 and as high as 540; the most recent is
6960-506: 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. 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
7047-684: The target of an attack, for example, by signalling that they are toxic or unpalatable , by signalling that a chase would be unprofitable, or by forming groups. If they become a target, they can try to fend off the attack with defences such as armour, quills , unpalatability, or mobbing; and they can often escape an attack in progress by startling the predator, playing dead , shedding body parts such as tails, or simply fleeing. Predators and prey are natural enemies, and many of their adaptations seem designed to counter each other. For example, bats have sophisticated echolocation systems to detect insects and other prey, and insects have developed
7134-499: The trend. Yellowstone cutthroat trout ( Oncorhynchus clarki bouvieri ) have suffered considerable declines since European settlement, but recently began flourishing in some areas. Especially in Yellowstone Lake itself, long-term records indicate an almost remarkable restoration of robust populations from only three decades ago when the numbers of this fish were depleted because of excessive harvest. Its current recovery, though
7221-565: The wider ecosystem. As a result, provisioning of species such as the tiger shark is controversial, but its effects are not well established by empirical evidence. Other affected apex predators include big cats and crocodiles. 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. In 2015, plans were made to reintroduce lynx to
7308-559: 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, especially during the autumn as they prepared to hibernate once again. The grizzly bear gives birth during hibernation, so the increased food supply is expected to produce an increase in the number of cubs observed. Dozens of other species, including eagles, ravens, magpies , coyotes, and black bears have also been documented as scavenging from wolf kills within
7395-449: 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. Among more recent fossils, the saber-tooth cats, like Smilodon , are considered to have been apex predators in the Cenozoic . Humans hunted with apex predators in
7482-644: Was removed, lake trout , the suppressed native apex predator, diversified its prey selection and increased its trophic level . 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. Predators that exert top-down control on organisms in their community are often considered keystone species . Apex predators can have profound effects on ecosystems, as
7569-401: Was used to hear signals used for territorial defence and mating. Their hearing evolved in response to bat predation, but the only clear example of reciprocal adaptation in bats is stealth echolocation. A more symmetric arms race may occur when the prey are dangerous, having spines, quills, toxins or venom that can harm the predator. The predator can respond with avoidance, which in turn drives
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