Surplus killing, also known as excessive killing, henhouse syndrome, [1] [2] or overkill, [3] is a common behavior exhibited by predators, in which they kill more prey than they can immediately eat and then they either cache or abandon the remainder. The term was invented by Dutch biologist Hans Kruuk after studying spotted hyenas in Africa [4] and red foxes in England. [5] [6]
Some animals which have been observed engaging in surplus killing hunt alone, some are mainly pack hunters. Some opinions include humans. [7]
Bears: brown bears, [8] [9] American black bears, [10] polar bears. [11]
Large cats: jaguar [ citation needed ], leopards, [12] lions, [11] [12] lynxes. [13]
Canines: wolves, [14] coyotes, [11] [15] red fox, [5] [6] dogs.[ citation needed ]
Others: martens, [16] weasels, [17] honey badgers, [12] minks, [18] raccoons, [19] spotted hyena, [4] orcas. [20]
Invertebrae: zooplankton, [21] damselfly naiads, [22] predaceous mites [ citation needed ], spiders. [12]
In Tasmania, in a single dog attack, 58 little penguins were killed. [23] In mainland Australia, a single fox once killed around 74 penguins over several days, eating almost nothing. [24] One leopard in Cape Province, South Africa killed 51 sheep and lambs in a single incident. [25] Similarly, two caracal in Cape Province killed 22 sheep in one night, eating only part of the buttock of one carcass. [26] Up to 19 spotted hyenas once killed 82 Thomson's gazelle and badly injured 27, eating just 16%. [1]
In late autumn, least weasels often surplus-kill vole and then dig them up and eat them on winter days when it is too cold to hunt. In March 2016, a pack of 9 grey wolves in Wyoming was found to have killed 19 elk. John Lund, of the Wyoming Game and Fish Department, said that he had never documented surplus killings that extreme from grey wolves. [27] In Florida, laboratory experiments documented cases of surplus killing in larvae of the predatory midge Corethrella appendiculata against specific larval stages of different species of mosquitoes of the genus Toxorhynchites . [28]
In surplus killing, predators eat only the most-preferred animals and animal parts. Bears engaging in surplus killing of salmon are more likely to eat unspawned fish because of higher muscle quality, and high-energy parts such as brains and eggs. [1] Surplus killing can deplete the overall food supply, waste predator energy and risk their being injured. Nonetheless, researchers say animals surplus-kill whenever they can, in order to procure food for offspring and others, to gain valuable killing experience, and to create the opportunity to eat the carcass later when they are hungry again. [1] [29]
The coyote, also known as the American jackal, prairie wolf, or brush wolf, is a species of canine native to North America. It is smaller than its close relative, the gray wolf, and slightly smaller than the closely related eastern wolf and red wolf. It fills much of the same ecological niche as the golden jackal does in Eurasia; however, the coyote is generally larger.
Hyenas or hyaenas are feliform carnivoran mammals belonging to the family Hyaenidae. With just four extant species, it is the fifth-smallest family in the order Carnivora and one of the smallest in the class Mammalia. Despite their low diversity, hyenas are unique and vital components of most African ecosystems.
The wolf, also known as the gray wolf or grey wolf, is a canine native to Eurasia and North America. More than thirty subspecies of Canis lupus have been recognized, including the dog and dingo, though gray wolves, as popularly understood, only comprise naturally-occurring wild subspecies. The wolf is the largest wild extant member of the family Canidae, and is further distinguished from other Canis species by its less pointed ears and muzzle, as well as a shorter torso and a longer tail. The wolf is nonetheless related closely enough to smaller Canis species, such as the coyote and the golden jackal, to produce fertile hybrids with them. The wolf's fur is usually mottled white, brown, gray, and black, although subspecies in the arctic region may be nearly all white.
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.
The cougar, also known as the panther, mountain lion, catamount and puma, is a large cat native to the Americas. It inhabits North, Central and South America, making it the most widely distributed wild, terrestrial mammal in the Western Hemisphere, and one of the most widespread in the world. Its range spans the Yukon, British Columbia and Alberta provinces of Canada, the Rocky Mountains and areas in the western United States. Further south, its range extends through Mexico to the Amazon Rainforest and the southern Andes Mountains in Patagonia. 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.
The spotted hyena, also known as the laughing hyena, is a hyena species, currently classed as the sole extant member of the genus Crocuta, native to sub-Saharan Africa. It is listed as being of least concern by the IUCN due to its widespread range and large numbers estimated between 27,000 and 47,000 individuals. The species is, however, experiencing declines outside of protected areas due to habitat loss and poaching. Populations of Crocuta, usually considered a subspecies of Crocuta crocuta, known as cave hyenas, roamed across Eurasia for at least one million years until the end of the Late Pleistocene. The spotted hyena is the largest extant member of the Hyaenidae, and is further physically distinguished from other species by its vaguely bear-like build, rounded ears, less prominent mane, spotted pelt, more dual-purposed dentition, fewer nipples, and pseudo-penis. It is the only placental mammalian species where females have a pseudo-penis and lack an external vaginal opening.
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.
The Arabian wolf is a subspecies of gray wolf native to the Arabian Peninsula—to the west of Bahrain, as well as Oman, southern Saudi Arabia, and Yemen. It is also found in Israel’s Negev and Arava Deserts, Jordan, Palestine, and Egypt's Sinai Peninsula. It is the smallest gray wolf subspecies and a specialized xerocole (arid-adapted) animal that normally lives in smaller familial packs. Arabian wolves are omnivorous and opportunistic eaters; they consume small to medium-sized prey, from insects, reptiles and birds to rodents and small ungulates, such as young Nubian ibex and several species of gazelle.
A man-eating animal or man-eater is an individual animal or being that preys on humans as a pattern of hunting behavior. This does not include the scavenging of corpses, a single attack born of opportunity or desperate hunger, or the incidental eating of a human that the animal has killed in self-defense. However, all three cases may habituate an animal to eating human flesh or to attacking humans, and may foster the development of man-eating behavior.
Along with parasites and disease, predation is a threat to sheep health and consequently to the profitability of sheep raising. Sheep have very little ability to defend themselves, even when compared with other prey species kept as livestock. Even if sheep are not directly bitten or survive an attack, they may die from panic or from injuries sustained.
The African wild dog, also known as the painted dog or Cape hunting dog, is a wild canine native to sub-Saharan Africa. It is the largest wild canine in Africa, and the only extant member of the genus Lycaon, which is distinguished from Canis by dentition highly specialised for a hypercarnivorous diet and by a lack of dewclaws.
An avivore is a specialized predator of birds, with birds making up a large proportion of its diet. Such bird-eating animals come from a range of groups.
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.
Antipredatory behaviors are actions an animal performs to reduce or rid themselves of the risk of being prey. Many studies have been done on elk to see what their antipredator behaviors consist of.
Pursuit predation is a form of predation in which predators actively give chase to their prey, either solitarily or as a group. It is an alternate predation strategy to ambush predation — pursuit predators rely on superior speed, endurance and/or teamwork to seize the prey, while ambush predators use concealment, luring, exploiting of surroundings and the element of surprise to capture the prey. While the two patterns of predation are not mutually exclusive, morphological differences in an organism's body plan can create an evolutionary bias favoring either type of predation.
The northern lynx is a medium-sized subspecies of the Eurasian lynx.
Single wolves or mated pairs typically have higher success rates in hunting than do large packs; single wolves have occasionally been observed to kill large prey such as moose, bison and muskoxen unaided. This contrasts with the commonly held belief that larger packs benefit from cooperative hunting to bring down large game. The size of a wolf hunting pack is related to the number of pups that survived the previous winter, adult survival, and the rate of dispersing wolves leaving the pack. The optimal pack size for hunting elk is four wolves, and for bison a large pack size is more successful.
The spotted hyena is the most carnivorous member of the Hyaenidae. Unlike its brown and striped cousins, the spotted hyena is primarily a predator rather than a scavenger. One of the earliest studies to demonstrate its hunting abilities was done by Hans Kruuk, a Dutch wildlife ecologist who showed through a 7-year study of hyena populations in Ngorongoro and Serengeti National Park during the 1960s that spotted hyenas hunt as much as lions, and with later studies this has been shown to be the average in all areas of Africa. However spotted hyenas remain mislabeled as scavengers, often even by ecologists and wildlife documentary channels.
The brown bear is one of the most omnivorous animals in the world and has been recorded to consume the greatest variety of foods of any bear. Throughout life, this species is regularly curious about the potential of eating virtually any organism or object that they encounter. Certainly no other animal in their given ecosystems, short perhaps of other bear species and humans, can claim to feed on as broad a range of dietary opportunities. Food that is both abundant and easily obtained is preferred. Their jaw structure has evolved to fit their dietary habits. Their diet varies enormously throughout their differing areas based on opportunity. In spring, winter-provided carrion, grasses, shoots, sedges and forbs are the dietary mainstays for brown bears from almost every part of their distribution. Fruits, including berries, become increasingly important during summer and early autumn. Roots and bulbs become critical in autumn for some inland bear populations if fruit crops are poor. The dietary variability is illustrated in the western United States, as meat made up 51% of the average year-around diet for grizzly bears from Yellowstone National Park, while it made up only 11% of the year-around diet for grizzlies from Glacier National Park a few hundred miles to the north.
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.
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