Scavengers are animals that consume dead organisms that have died from causes other than predation. 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.
Scavengers aid in overcoming fluctuations of food resources in the environment. The process and rate of scavenging is affected by both biotic and abiotic factors, such as carcass size, habitat, temperature, and seasons.
Scavenger is an alteration of scavager, from Middle English skawager meaning "customs collector", from skawage meaning "customs", from Old North French escauwage meaning "inspection", from schauwer meaning "to inspect", of Germanic origin; akin to Old English scēawian and German schauen meaning "to look at", and modern English "show" (with semantic drift).
Obligate scavenging is rare among vertebrates, due to the difficulty of finding enough carrion without expending too much energy. In vertebrates, only vultures and possibly some pterosaurs are obligate scavengers, as terrestrial soaring flyers are the only animals able to find enough carrion.
Most scavenging animals are facultative scavengers that gain most of their food through other methods, especially predation. Many large carnivores that hunt regularly, such as hyenas and jackals, but also animals rarely thought of as scavengers, such as African lions, leopards, and wolves will scavenge if given the chance. They may also use their size and ferocity to intimidate the original hunters (the cheetah is a notable exception). Almost all scavengers above insect size are predators and will hunt if not enough carrion is available, as few ecosystems provide enough dead animals year-round to keep its scavengers fed on that alone. Scavenging wild dogs and crows frequently exploit roadkill.
Scavengers of dead plant material include termites that build nests in grasslands and then collect dead plant material for consumption within the nest. The interaction between scavenging animals and humans is seen today most commonly in suburban settings with animals such as opossums, polecats and raccoons. In some African towns and villages, scavenging from hyenas is also common.
In the prehistoric eras, the species Tyrannosaurus rex may have been an apex predator, preying upon hadrosaurs, ceratopsians, and possibly juvenile sauropods, although some experts have suggested the dinosaur was primarily a scavenger. The debate about whether Tyrannosaurus was an apex predator or scavenger was among the longest ongoing feuds in paleontology; however, most scientists now agree that Tyrannosaurus was an opportunistic carnivore, acting mostly as a predator but scavenging when it could. Recent research also shows that while an adult Tyrannosaurus rex would energetically gain little though scavenging, smaller theropods of approximately 500 kg (1,100 lb) may have potentially gained levels similar to that of hyenas, though not enough for them to rely on scavenging. There are also an info that Otodus megalodon, Ceratosaurus, Andrewsarchus and some more prehistoric animals were scavengers. Animals which consume feces, such as dung beetles, are referred to as coprovores. Animals that collect small particles of dead organic material of both animal and plant origin are referred to as detritivores.
Scavengers play a fundamental role in the environment through the removal of decaying organisms, serving as a natural sanitation service. While microscopic and invertebrate decomposers break down dead organisms into simple organic matter which are used by nearby autotrophs, scavengers help conserve energy and nutrients obtained from carrion within the upper trophic levels, and are able to disperse the energy and nutrients farther away from the site of the carrion than decomposers.
Scavenging unites animals which normally would not come into contact, and results in the formation of highly structured and complex communities which engage in nonrandom interactions. Scavenging communities function in the redistribution of energy obtained from carcasses and reducing diseases associated with decomposition. Oftentimes, scavenger communities differ in consistency due to carcass size and carcass types, as well as by seasonal effects as consequence of differing invertebrate and microbial activity.
Competition for carrion results in the inclusion or exclusion of certain scavengers from access to carrion, shaping the scavenger community. When carrion decomposes at a slower rate during cooler seasons, competitions between scavengers decrease, while the number of scavenger species present increases.
Alterations in scavenging communities may result in drastic changes to the scavenging community in general, reduce ecosystem services and have detrimental effects on animal and humans. The reintroduction of gray wolves (Canis lupus) into Yellowstone National Park in the United States caused drastic changes to the prevalent scavenging community, resulting in the provision of carrion to many mammalian and avian species. Likewise, the reduction of vulture species in India lead to the increase of opportunistic species such as feral dogs and rats. The presence of both species at carcasses resulted in the increase of diseases such as rabies and bubonic plague in wildlife and livestock, as feral dogs and rats are transmitters of such diseases. Furthermore, the decline of vulture populations in India has been linked to the increased rates of anthrax in humans due to the handling and ingestion of infected livestock carcasses. An increase of disease transmission has been observed in mammalian scavengers in Kenya due to the decrease in vulture populations in the area, as the decrease in vulture populations resulted in an increase of the number of mammalian scavengers at a given carcass along with the time spent at a carcass.
Scavenging may provide a direct and indirect method for transmitting disease between animals. Scavengers of infected carcasses may become hosts for certain pathogens and consequently vectors of disease themselves. An example of this phenomenon is the increased transmission of tuberculosis observed when scavengers engage in eating infected carcasses. Likewise, the ingestion of bat carcasses infected with rabies by striped skunks (Mephitis mephitis) resulted in increased infection of these organisms with the virus.
A major vector of transmission of diseases are various bird species, with outbreak being influenced by such carrier birds and their environment. An avian cholera outbreak from 2006 to 2007 off the coast Newfoundland, Canada resulted in the mortality of many marine bird species. The transmission, perpetuation and spread of the outbreak was mainly restricted to gull species who scavenge for food in the area. Similarly, an increase of transmission of avian influenza virus to chickens by domestic ducks from Indonesian farms permitted to scavenge surrounding areas was observed in 2007. The scavenging of ducks in rice paddy fields in particular resulted in increased contact with other bird species feeding on leftover rice, which may have contributed to increased infection and transmission of the avian influenza virus. The domestic ducks may not have demonstrated symptoms of infection themselves, though were observed to excrete high concentrations of the avian influenza virus.
Many species that scavenge face persecution globally. Vultures in particular have faced incredible persecution and threats by humans. Before its ban by regional governments in 2006, the veterinary drug Diclofenac has resulted in at least a 95% decline of Gyps vultures in Asia. Habitat loss and food shortage have contributed to the decline of vulture species in West Africa due to the growing human population and overhunting of vulture food sources, as well as changes in livestock husbandry. Poisoning certain predators to increase the number of game animals is still a common hunting practice in Europe and contributes to the poisoning of vultures when they consume the carcasses of poisoned predators.
In the 1970s Lewis Binford suggested that early humans primarily obtained meat via scavenging, not through hunting. In 2010, Dennis Bramble and Daniel Lieberman proposed that early carnivorous human ancestors subsequently developed long-distance running behaviors which improved the ability to scavenge and hunt: they could reach scavenging sites more quickly and also pursue a single animal until it could be safely killed at close range due to exhaustion and hyperthermia.
In modern humans, necrophagy (eating of dead/decaying flesh) occurs rarely in most societies. This is likely an adaptation to the risk of disease, due to humans having lower levels of protective acids in the digestive tract, compared to species that are dedicated scavengers. Many instances have occurred in history, especially in times of war, where necrophagy and cannibalism can emerge as a survival behavior.
"Scavenger" appears as an occupation in the 1911 Census of England and Wales. This job title applied to someone who cleans the streets and removes refuse, generally a workman (a modern-day garbage collector, janitor, or street cleaner) employed by the local public health authority.
In India, the term "manual scavenging" is used to describe the removal of raw (fresh and untreated) human excreta from buckets or other containers that are used as toilets or from the pits of pit latrines. The workers pile the excreta into baskets and may carry these on their heads to locations sometimes several kilometers from the latrines. India has officially prohibited the employment of manual scavengers since 1993, but the practice continues as of 2014.
The term "scavenger" originated as "scavager" or "scaveger", an official concerned with the receipt of custom duties and the inspection (scavage) of imported goods. The "scavagers" are found with such officials of the City of London as an aleconner or beadle. These officials seem to have been charged also with the cleaning of the streets, and the name superseded the older rakyer for those who performed this duty. These professions are essential to urban settings operating at the highest capacity. The garbage-collection jobs and scavenging professions allow urban populations to continue unhindered by outbreaks of disease most commonly caused by the build-up of physical waste. These jobs had great importance before the times of functional sewer systems and of indoor plumbing.
Human endurance running performance capabilities compare favourably with those of other mammals and probably emerged sometime around 2 million years ago in order to help meat-eating hominids compete with other carnivores. [...] [S]mall teeth, larger bodies and archaeological remains suggest that hominids started to incorporate meat and other animal tissues in the diet at least 2.5Ma, probably by hunting as well as scavenging. [...] [Endurance running] might have enabled hominids to scavenge carcasses from lions after they were abandoned but before hyenas arrived, as modern hunter-gatherers still do in East Africa.
Antioxidants are compounds that inhibit oxidation. Oxidation is a chemical reaction that can produce free radicals, thereby leading to chain reactions that may damage the cells of organisms. Antioxidants such as thiols or ascorbic acid (vitamin C) terminate these chain reactions. To balance the oxidative state, plants and animals maintain complex systems of overlapping antioxidants, such as glutathione and enzymes (e.g., catalase and superoxide dismutase), produced internally, or the dietary antioxidants vitamin C, and vitamin E.
The term "antioxidant" is mostly used for two entirely different groups of substances: industrial chemicals that are added to products to prevent oxidation, and naturally occurring compounds that are present in foods and tissue. The former, industrial antioxidants, have diverse uses: acting as preservatives in food and cosmetics, and being oxidation-inhibitors in fuels.Antioxidant dietary supplements have not been shown to improve health in humans, or to be effective at preventing disease. Supplements of beta-carotene, vitamin A, and vitamin E have no positive effect on mortality rate or cancer risk. Additionally, supplementation with selenium or vitamin E do not reduce the risk of cardiovascular disease.CD163
CD163 (Cluster of Differentiation 163) is a protein that in humans is encoded by the CD163 gene. CD163 is the high affinity scavenger receptor for the hemoglobin-haptoglobin complex and in the absence of haptoglobin - with lower affinity - for hemoglobin alone. It also is a marker of cells from the monocyte/macrophage lineage. CD163 functions as innate immune sensor for gram-positive and gram-negative bacteria. The receptor was discovered in 1987.CD36
CD36 (cluster of differentiation 36), also known as platelet glycoprotein 4, fatty acid translocase (FAT), scavenger receptor class B member 3 (SCARB3), and glycoproteins 88 (GP88), IIIb (GPIIIB), or IV (GPIV) is a protein that in humans is encoded by the CD36 gene. The CD36 antigen is an integral membrane protein found on the surface of many cell types in vertebrate animals. It imports fatty acids inside cells and is a member of the class B scavenger receptor family of cell surface proteins. CD36 binds many ligands including collagen, thrombospondin, erythrocytes parasitized with Plasmodium falciparum, oxidized low density lipoprotein, native lipoproteins, oxidized phospholipids, and long-chain fatty acids.Work in genetically modified rodents suggest a role for CD36 in fatty acid metabolism, heart disease, taste, and dietary fat processing in the intestine. It may be involved in glucose intolerance, atherosclerosis, arterial hypertension, diabetes, cardiomyopathy and Alzheimer's disease.CD68
CD68 (Cluster of Differentiation 68) is a protein highly expressed by cells in the monocyte lineage (e.g., monocytic phagocytes, osteoclasts), by circulating macrophages, and by tissue macrophages (e.g., Kupffer cells, microglia).Hybosoridae
Hybosoridae, sometimes known as the scavenger scarab beetles, is a family of scarabaeiform beetles. The 690 species in 97 genera occur widely in the tropics, but little is known of their biology.
Hybosorids are small, 5–7 mm in length and oval in shape. Color ranges from a glossy light brown to black. They are distinctive for their large mandibles and labrum, and their 10-segmented antennae, in which the 8th antennomore of the club is deeply grooved and occupied by the 9th and 10th antennomeres. The legs have prominent spurs.
The larvae have the C-shape and creamy white appearance typical of the scarabaeiforms. The 4-segmented legs are well-developed; the front legs are used to stridulate by rubbing against the margin of the epipharynx, a habit unique to this family.
Adults are known to feed on invertebrate and vertebrate carrion, with some found in dung. Larvae have been found in decomposing plant material. Little more is known of their life histories.
The group has been long recognized as distinct, primarily because of the larval characteristics, either as a distinct family or as a subfamily of Scarabaeidae.Hydrophilidae
Hydrophilidae, also called water scavenger beetles, is a family of chiefly aquatic beetles. Aquatic hydrophilids are notable for their long maxillary palps, which are longer than their antennae. Several of the former subfamilies of Hydrophilidae have recently been removed and elevated to family rank; Epimetopidae, Georissidae (= Georyssinae), Helophoridae, Hydrochidae, and Spercheidae (= Sphaeridiinae). Some of these formerly-included groups are primarily terrestrial or semi-aquatic.The vernacular name water scavenger beetles is not an accurate description of their habit. With rare exceptions, the larvae are predatory while the adults may be vegetarians or predators in addition to scavenging. Many species are able to produce sounds.Species of Hydrophilus are reported as pests in fish hatcheries. Other species are voracious consumers of mosquito larvae, and have potential as biological control agents.
There are 2,835 species in 169 generaHydrophiloidea
Hydrophiloidea is a superfamily of beetles. Until recently it was only a single family, the water scavenger beetles (Hydrophilidae), but several of the subfamilies have been removed and raised to family rank.
The present list of recognized families is thus:
Georissidae (= Georyssidae)
Spercheidae (= Sphaeridiidae)The Histeroidea seem to be very closely related and may be part of an extended Hydrophiloidea clade; some researchers have proposed merging the two superfamilies into one.Latridiidae
Latridiidae is a family of tiny, little-known beetles commonly called minute brown scavenger beetles. The number of described species currently stands at around 1050 in 29 genera but the number of species is undoubtedly much higher.MSR1
Macrophage scavenger receptor 1, also known as MSR1, is a protein which in humans is encoded by the MSR1 gene.MSR1 has also recently been designated CD204 (cluster of differentiation 204).Manual scavenging
Manual scavenging is a term used mainly in India for the manual removal of untreated human excreta from bucket toilets or pit latrines by hand with buckets and shovels. It has been officially prohibited by law in 1993 due to it being regarded as a caste-based, dehumanizing practice (if not done in a safe manner). It involves moving the excreta, using brooms and tin plates, into baskets, which the workers carry to disposal locations sometimes several kilometers away. The workers, called scavengers (or more appropriately "sanitation workers"), rarely have any personal protective equipment. Manual scavenging is a caste-based occupation, with the vast majority of workers involved being women.The employment of manual scavengers to empty a certain type of dry toilet that requires manual daily emptying was prohibited in India in 1993. The law was extended and clarified to include insanitary latrines, ditches and pits in 2013.According to Socio Economic Caste Census 2011, 180,657 households are engaged in manual scavenging for a livelihood. The 2011 Census of India found 794,000 cases of manual scavenging across India. The state of Maharashtra, with 63,713, tops the list with the largest number of households working as manual scavengers, followed by the states of Madhya Pradesh, Uttar Pradesh, Tripura and Karnataka.Similar occupations existed and still exist in other countries, usually known by other terms and given different degrees of government protection.Oxygen scavenger
Oxygen scavengers or oxygen absorbers are added to enclosed packaging to help remove or decrease the level of oxygen in the package. They are used to help maintain product safety and extend shelf life.
There are many types of oxygen absorbers available to cover a wide array of applications.The components of an oxygen absorber vary according to intended use, the water activity of the product being preserved, and other factors. Often the oxygen absorber or scavenger is enclosed in a porous sachet or packet but it can also be part of packaging films and structures. Others are part of a polymer structure.Scavenger (audio drama)
Scavenger is a Big Finish Productions audio drama based on the long-running British science fiction television series Doctor Who.Scavenger (comics)
The Scavenger is the name of two DC Comics supervillains with no known connections with each other. The first Scavenger was Peter Mortimer, an Aquaman villain who debuted in Aquaman vol. 1 #37 (January 1968), and was created by Bob Haney and Nick Cardy. He is re-introduced in the New 52 series Aquaman by writer Geoff Johns and artist Paul Pelletier.The second Scavenger first appeared in Superboy #2 (March 1994), and was created by Karl Kesel and Tom Grummett.Scavenger hunt
A scavenger hunt is a party game in which the organizers prepare a list defining specific items, which the participants seek to gather or complete all items on the list, usually without purchasing them. Usually participants work in small teams, although the rules may allow individuals to participate. The goal is to be the first to complete the list or to complete the most items on that list.
In variations of the game, players take photographs of listed items or be challenged to complete the tasks on the list in the most creative manner. A scavenger hunt is distinguished from a treasure hunt, in that the latter involves one or a few items that are desirable and completed in sequence, while a scavenger hunt primarily collects undesirable or useless objects in random order.According to game scholar Markus Montola, scavenger hunts evolved from ancient folk games. Gossip columnist Elsa Maxwell popularized scavenger hunts in the United States with a series of exclusive New York parties starting in the early 1930s. The scavenger-hunt craze among New York's elite was satirized in the 1936 film My Man Godfrey, where one of the items socialite players are trying to collect is a "Forgotten Man", a homeless person.Scavenger hunts are regularly held at American universities, a notable modern example being the University of Chicago Scavenger Hunt, founded in 1987. The town of Provo in Utah currently holds the Guinness World Record for organizing the world's largest scavenger hunt with 2,079 participants.One variation of scavenger hunt is to have players solve clues and these solutions point to the object, which is to be collected.Sciomyzoidea
Sciomyzoidea is a superfamily of Acalyptratae flies.
The families placed here are:
Coelopidae – seaweed flies
Sepsidae – scavenger flies
Sciomyzidae – marsh flies, snail-killing flies (including Huttoninidae, Phaeomyiidae, Tetanoceridae)The Addams Family (video game series)
There have been five video games based on The Addams Family television series and films, released between 1989 and 2001 on various home video game consoles.University of Chicago Scavenger Hunt
The University of Chicago Scavenger Hunt (or Scav Hunt, colloquially Scav) is an annual four-day team-based scavenger hunt held at the University of Chicago from Thursday to Sunday of Mother's Day weekend in May. The list of items, usually over 300 items long, encompasses cryptograms, competitions, build challenges, a 3 course meal, and a 2,000 mile road trip. "Scav Hunt" is well known for its quirky, strange, or impossible items. Scav held the Guinness World Record for largest scavenger hunt from 2011 to 2014.Vulture
A vulture is a scavenging bird of prey. The two types of vultures are the New World vultures, including the Californian and Andean condors, and the Old World vultures, including the birds that are seen scavenging on carcasses of dead animals on African plains. Some traditional Old World vultures (including the bearded vulture) are not closely related to the others, which is why the vultures are to be subdivided into three taxa rather than two. New World vultures are found in North and South America; Old World vultures are found in Europe, Africa, and Asia, meaning that between the two groups, vultures are found on every continent except Australia and Antarctica (though Trigonoceps vultures have crossed the Wallacea line).A particular characteristic of many vultures is a bald head, devoid of normal feathers. Although it has been historically believed to help keep the head clean when feeding, the bare skin may play an important role in thermoregulation. Vultures have been observed to hunch their bodies and tuck in their heads in the cold, and open their wings and stretch their necks in the heat. Vultures also use urine as a way to keep themselves cool by urinating on themselves.A group of vultures is called a kettle, committee or wake. The term kettle refers to vultures in flight, while committee refers to vultures resting on the ground or in trees. Wake is reserved for a group of vultures that are feeding. The word Geier (taken from the German language) does not have a precise meaning in ornithology; it is occasionally used to refer to a vulture in English, as in some poetry.