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.
58-439: The marabou stork ( Leptoptilos crumenifer ) is a large wading bird in the stork family Ciconiidae native to sub-Saharan Africa . It breeds in both wet and arid habitats, often near human habitation, especially landfill sites. It is sometimes called the " undertaker bird" due to its shape from behind: cloak-like wings and back, skinny white legs, and sometimes a large white mass of "hair". It has often been credited with
116-507: A purse around the neck". The species is now placed with the lesser adjutant and the greater adjutant in the genus Leptoptilos that Lesson had introduced at the same time he described the marabou stork. The species is monotypic : no subspecies are recognised. The common name marabou is thought to be derived from the Arabic word murābit meaning quiet or hermit-like. The species was originally described as Ciconia crumenifera . When
174-602: 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 over-hunting 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
232-744: A better sense of smell. A third stage of bird evolution starting with Ornithothoraces (the "bird-chested" avialans) can be associated with the refining of aerodynamics and flight capabilities, and the loss or co-ossification of several skeletal features. Particularly significant are the development of an enlarged, keeled sternum and the alula , and the loss of grasping hands. † Anchiornis † Archaeopteryx † Xiaotingia † Rahonavis † Jeholornis † Jixiangornis † Balaur † Zhongjianornis † Sapeornis † Confuciusornithiformes † Protopteryx † Pengornis Ornithothoraces † Enantiornithes Scavenger Scavengers aid in overcoming fluctuations of food resources in
290-473: A definition similar to "all theropods closer to birds than to Deinonychus ", with Troodon being sometimes added as a second external specifier in case it is closer to birds than to Deinonychus . Avialae is also occasionally defined as an apomorphy-based clade (that is, one based on physical characteristics). Jacques Gauthier , who named Avialae in 1986, re-defined it in 2001 as all dinosaurs that possessed feathered wings used in flapping flight , and
348-425: 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,
406-442: A group called Paraves . Some basal members of Deinonychosauria, such as Microraptor , have features which may have enabled them to glide or fly. The most basal deinonychosaurs were very small. This evidence raises the possibility that the ancestor of all paravians may have been arboreal , have been able to glide, or both. Unlike Archaeopteryx and the non-avialan feathered dinosaurs, who primarily ate meat, studies suggest that
464-439: A high metabolic rate, a four-chambered heart , and a strong yet lightweight skeleton . Birds live worldwide and range in size from the 5.5 cm (2.2 in) bee hummingbird to the 2.8 m (9 ft 2 in) common ostrich . There are over 11,000 living species and they are split into 44 orders . More than half are passerine or "perching" birds. Birds have wings whose development varies according to species;
522-473: 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
580-406: A sister group, the order Crocodilia , contain the only living representatives of the reptile clade Archosauria . During the late 1990s, Aves was most commonly defined phylogenetically as all descendants of the most recent common ancestor of modern birds and Archaeopteryx lithographica . However, an earlier definition proposed by Jacques Gauthier gained wide currency in the 21st century, and
638-483: A species of midge fly whose larvae live as obligate scavengers at the bottom of lakes and whose adults almost never feed and only live up to a few weeks. 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
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#1732790299964696-717: A time, sometimes for years, and rarely for life. Other species have breeding systems that are polygynous (one male with many females) or, rarely, polyandrous (one female with many males). Birds produce offspring by laying eggs which are fertilised through sexual reproduction . They are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching. Many species of birds are economically important as food for human consumption and raw material in manufacturing, with domesticated and undomesticated birds being important sources of eggs, meat, and feathers. Songbirds , parrots, and other species are popular as pets. Guano (bird excrement)
754-708: Is 43 years in captivity and 25 years in wild. The marabou stork is a frequent scavenger , and the naked head and long neck are adaptations to this livelihood, as it is with the vultures with which the stork often feeds. In both cases, a feathered head would become rapidly clotted with blood and other substances when the bird's head was inside a large corpse, and the bare head is easier to keep clean. This large and powerful bird eats mainly carrion , scraps, and faeces but will opportunistically eat almost any animal matter it can swallow. It occasionally eats other birds including Quelea nestlings, pigeons , doves , pelican and cormorant chicks, and even flamingos . During
812-613: Is also used to make various noises at that time. The marabou stork breeds in Africa south of the Sahara. In East Africa, the birds interact with humans and breed in urban areas. In southern African countries, the birds breed mainly in less populated areas. The marabou stork breeds in colonies, starting during the dry season. The female lays two to three eggs in a small nest made of sticks; eggs hatch after an incubation period of 30 days. Their young reach sexual maturity at 4 years of age. Lifespan
870-540: Is called ornithology . Birds are feathered theropod dinosaurs and constitute the only known living dinosaurs . Likewise, birds are considered reptiles in the modern cladistic sense of the term, and their closest living relatives are the crocodilians . Birds are descendants of the primitive avialans (whose members include Archaeopteryx ) which first appeared during the Late Jurassic . According to recent estimates, modern birds ( Neornithes ) evolved in
928-420: Is frequently used in the trimming of various items of clothing and hats, as well as fishing lures . Turkey down and similar feathers have been used as a substitute for making 'marabou' trimming. Bird Birds are a group of warm-blooded vertebrates constituting the class Aves ( Latin: [ˈaveːs] ), characterised by feathers , toothless beaked jaws, the laying of hard-shelled eggs,
986-429: Is harvested for use as a fertiliser. Birds figure throughout human culture. About 120 to 130 species have become extinct due to human activity since the 17th century, and hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational birdwatching is an important part of the ecotourism industry. The first classification of birds
1044-503: Is not considered a direct ancestor of birds, though it is possibly closely related to the true ancestor. Over 40% of key traits found in modern birds evolved during the 60 million year transition from the earliest bird-line archosaurs to the first maniraptoromorphs , i.e. the first dinosaurs closer to living birds than to Tyrannosaurus rex . The loss of osteoderms otherwise common in archosaurs and acquisition of primitive feathers might have occurred early during this phase. After
1102-477: Is not reached for up to four years. Like most storks, the marabou is gregarious and a colonial breeder . In the African dry season (when food is more readily available as the pools shrink), it builds a tree nest in which two or three eggs are laid. It is known to be quite ill-tempered. It also resembles other storks in that it is not very vocal, but indulges in bill-rattling courtship displays . The throat sac
1160-483: Is now. For example, a single 40 tonne Apatosaurus carcass would have been worth roughly 6 years of calories for an average allosaur. As a result of this resource oversupply, it is possible that some theropods evolved to get most of their calories by scavenging giant sauropod carcasses, and may not have needed to consistently hunt in order to survive. The same study suggested that theropods in relatively sauropod-free environments, such as tyrannosaurs, were not exposed to
1218-401: Is rare among vertebrates, due to the difficulty of finding enough carrion without expending too much energy. Well-known invertebrate scavengers of animal material include burying beetles and blowflies , which are obligate scavengers, and yellowjackets . Fly larvae are also common scavengers for organic materials at the bottom of freshwater bodies. For example, Tokunagayusurika akamusi is
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#17327902999641276-516: Is synonymous to Avifilopluma. † Scansoriopterygidae † Eosinopteryx † Jinfengopteryx † Aurornis † Dromaeosauridae † Troodontidae Avialae Based on fossil and biological evidence, most scientists accept that birds are a specialised subgroup of theropod dinosaurs and, more specifically, members of Maniraptora , a group of theropods which includes dromaeosaurids and oviraptorosaurs , among others. As scientists have discovered more theropods closely related to birds,
1334-535: Is used by many scientists including adherents to the PhyloCode . Gauthier defined Aves to include only the crown group of the set of modern birds. This was done by excluding most groups known only from fossils , and assigning them, instead, to the broader group Avialae, on the principle that a clade based on extant species should be limited to those extant species and their closest extinct relatives. Gauthier and de Queiroz identified four different definitions for
1392-722: The Late Cretaceous and diversified dramatically around the time of the Cretaceous–Paleogene extinction event 66 million years ago, which killed off the pterosaurs and all non- ornithuran dinosaurs. Many social species preserve knowledge across generations ( culture ). Birds are social, communicating with visual signals, calls, and songs , and participating in such behaviour as cooperative breeding and hunting, flocking , and mobbing of predators. The vast majority of bird species are socially (but not necessarily sexually) monogamous , usually for one breeding season at
1450-669: The Tiaojishan Formation of China, which has been dated to the late Jurassic period ( Oxfordian stage), about 160 million years ago. The avialan species from this time period include Anchiornis huxleyi , Xiaotingia zhengi , and Aurornis xui . The well-known probable early avialan, Archaeopteryx , dates from slightly later Jurassic rocks (about 155 million years old) from Germany . Many of these early avialans shared unusual anatomical features that may be ancestral to modern birds but were later lost during bird evolution. These features include enlarged claws on
1508-576: The Towers of Silence to be eaten by vultures and wild dogs. Studies in behavioral ecology and ecological epidemiology have shown that cannibalistic necrophagy , although rare, has been observed as a survival behavior in several social species , including anatomically modern humans ; however, episodes of human cannibalism occur rarely in most human societies. Many instances have occurred in human history , especially in times of war and famine , where necrophagy and human cannibalism emerged as
1566-608: 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,
1624-416: 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 Tibetan Buddhism the practice of excarnation – that is, the exposure of dead human bodies to carrion birds and/or other scavenging animals – is the distinctive characteristic of sky burial , which involves
1682-428: The appearance of Maniraptoromorpha, the next 40 million years marked a continuous reduction of body size and the accumulation of neotenic (juvenile-like) characteristics. Hypercarnivory became increasingly less common while braincases enlarged and forelimbs became longer. The integument evolved into complex, pennaceous feathers . The oldest known paravian (and probably the earliest avialan) fossils come from
1740-433: 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
1798-509: The birds that descended from them. Despite being currently one of the most widely used, the crown-group definition of Aves has been criticised by some researchers. Lee and Spencer (1997) argued that, contrary to what Gauthier defended, this definition would not increase the stability of the clade and the exact content of Aves will always be uncertain because any defined clade (either crown or not) will have few synapomorphies distinguishing it from its closest relatives. Their alternative definition
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1856-563: The breeding season, adults scale back on carrion and take mostly small, live prey since nestlings need this kind of food to survive. Common prey at this time may consist of fish, frogs, insects, eggs, small mammals and reptiles such as crocodile hatchlings and eggs, lizards and snakes. Though known to eat putrid and seemingly inedible foods, these storks may sometimes wash food in water to remove soil. When feeding on carrion, marabou frequently follow vultures, which are better equipped with hooked bills for tearing through carrion meat and may wait for
1914-633: The carcasses of poisoned predators. Highly efficient scavengers, also known as dominant or apex-scavengers, can have benefits to humans. Increases in dominant scavenger populations, such as vultures, can reduce populations of smaller opportunistic scavengers, such as rats. These smaller scavengers are often pests and disease vectors. In the 1980s, 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
1972-569: The chance. They may also use their size and ferocity to intimidate the original hunters (the cheetah is a notable victim, rather than a perpetrator). 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
2030-469: 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
2088-734: 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 also scavenging when it could sense it. Recent research also shows that while an adult T. rex would energetically gain little through scavenging, smaller theropods of approximately 500 kg (1,100 lb) might have gained levels similar to those of hyenas, though not enough for them to rely on scavenging. Other research suggests that carcasses of giant sauropods may have made scavenging much more profitable to carnivores than it
2146-485: The dismemberment of human cadavers of whom the remains are fed to vultures , and traditionally the main funeral rite (alongside cremation ) used to dispose of the human body. A similar funerary practice that features excarnation can be found in Zoroastrianism ; in order to prevent the pollution of the sacred elements (fire, earth, and water) from contact with decomposing bodies , human cadavers are exposed on
2204-665: The earliest members of Aves, is removed from this group, becoming a non-avian dinosaur instead. These proposals have been adopted by many researchers in the field of palaeontology and bird evolution , though the exact definitions applied have been inconsistent. Avialae, initially proposed to replace the traditional fossil content of Aves, is often used synonymously with the vernacular term "bird" by these researchers. † Coelurus † Ornitholestes † Ornithomimosauria † Alvarezsauridae † Oviraptorosauria Paraves Most researchers define Avialae as branch-based clade, though definitions vary. Many authors have used
2262-615: 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 (subsisting entirely or mainly on dead animals)
2320-451: The first avialans were omnivores . The Late Jurassic Archaeopteryx is well known as one of the first transitional fossils to be found, and it provided support for the theory of evolution in the late 19th century. Archaeopteryx was the first fossil to display both clearly traditional reptilian characteristics—teeth, clawed fingers, and a long, lizard-like tail—as well as wings with flight feathers similar to those of modern birds. It
2378-469: 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
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2436-545: 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
2494-402: 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
2552-466: The largest wingspan of any land bird, with an average of 2.6 metres (8.5 ft) and some recorded examples of up to 3.2 metres (10 ft). The marabou stork was formally described in 1831 by the French naturalist René Lesson . He placed it in the stork genus Ciconia and coined the binomial name Ciconia crumenifera . He specified that locality as Senegal. The species epithet means "carrying
2610-561: 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
2668-454: 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
2726-523: The only known groups without wings are the extinct moa and elephant birds . Wings, which are modified forelimbs , gave birds the ability to fly, although further evolution has led to the loss of flight in some birds , including ratites , penguins , and diverse endemic island species. The digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly seabirds and some waterbirds , have further evolved for swimming. The study of birds
2784-402: The outermost half) can be seen in the evolution of maniraptoromorphs, and this process culminated in the appearance of the pygostyle , an ossification of fused tail vertebrae. In the late Cretaceous, about 100 million years ago, the ancestors of all modern birds evolved a more open pelvis, allowing them to lay larger eggs compared to body size. Around 95 million years ago, they evolved
2842-536: The previously clear distinction between non-birds and birds has become blurred. By the 2000s, discoveries in the Liaoning Province of northeast China, which demonstrated many small theropod feathered dinosaurs , contributed to this ambiguity. The consensus view in contemporary palaeontology is that the flying theropods, or avialans , are the closest relatives of the deinonychosaurs , which include dromaeosaurids and troodontids . Together, these form
2900-452: The same biological name "Aves", which is a problem. The authors proposed to reserve the term Aves only for the crown group consisting of the last common ancestor of all living birds and all of its descendants, which corresponds to meaning number 4 below. They assigned other names to the other groups. Lizards & snakes Turtles Crocodiles Birds Under the fourth definition Archaeopteryx , traditionally considered one of
2958-420: The same type of carrion oversupply, and were therefore forced to hunt in order to survive. 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
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#17327902999643016-551: The second toe which may have been held clear of the ground in life, and long feathers or "hind wings" covering the hind limbs and feet, which may have been used in aerial maneuvering. Avialans diversified into a wide variety of forms during the Cretaceous period. Many groups retained primitive characteristics , such as clawed wings and teeth, though the latter were lost independently in a number of avialan groups, including modern birds (Aves). Increasingly stiff tails (especially
3074-407: The species was moved into the genus Leptoptilos , the ending was modified to crumeniferus and this was used by many authors until it was noted that the correct masculine ending to match the genus is crumenifer . The marabou stork is a massive bird: large specimens are thought to reach a height of 152 centimetres (5 feet) and a weight of 9 kg (20 lb). A wingspan of 3.7 m (12 ft)
3132-422: The three Leptoptilos species fly with the neck retracted like a heron . The marabou is unmistakable due to its size, bare head and neck, black back, and white underparts. It has a huge bill, a pink gular sac at its throat ( crumenifer(us) means "carrier of a pouch for money"), a neck ruff, and white legs and black wings. The sexes are alike, but the young bird is browner and has a smaller bill. Full maturity
3190-1044: The vultures to cast aside a piece, steal a piece of meat directly from the vulture or wait until the vultures are done. As with vultures, marabou storks perform an important natural function by cleaning areas via their ingestion of carrion and waste. Increasingly, marabous have become dependent on human garbage and hundreds of the huge birds can be found around African dumps or waiting for a hand out in urban areas. Marabous eating human garbage have been seen to devour virtually anything that they can swallow, including shoes and pieces of metal. Marabous conditioned to eating from human sources have been known to lash out when refused food. Fully grown marabou storks have few natural enemies, and have high annual survival rate, though lions have reportedly preyed on some individuals in ambush. A number of endoparasites have been identified in wild marabous including Cheilospirura , Echinura and Acuaria nematodes , Amoebotaenia sphenoides (Cestoda) and Dicrocoelium hospes (Trematoda). Marabou down
3248-451: The wings, which is about a foot less than the average Andean condor wingspan and nearly two feet less than the average of the largest albatrosses and pelicans . Typical weight is 4.5–8 kg (10–17.5 lb), unusually as low as 4 kg (9 lb), and length (from bill to tail) is 120 to 130 cm (47 to 51 in). Females are smaller than males. Bill length can range from 26.4 to 35 cm (10.5 to 14 in). Unlike most storks,
3306-496: Was accepted by Fisher and Peterson, who ranked the species as having the largest wing-spread of any living bird. Even higher measurements of up to 4.06 m (13.3 ft) have been reported, although no measurement over 3.20 m (10.5 ft) has been verified. It is often credited with the largest spread of any landbird, to rival the Andean condor ; more typically, however, these storks measure 225–287 cm (7–9 ft) across
3364-466: Was developed by Francis Willughby and John Ray in their 1676 volume Ornithologiae . Carl Linnaeus modified that work in 1758 to devise the taxonomic classification system currently in use. Birds are categorised as the biological class Aves in Linnaean taxonomy . Phylogenetic taxonomy places Aves in the clade Theropoda as an infraclass or a subclass, more recently a subclass. Aves and
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