The jaguarundi or eyra is a small wild cat native to southern North America and South America. It has been listed as Least Concern on the IUCN Red List since 2002; the megareserves of the Amazon Basin are the only conservation units that can sustain long-term viable populations. In some Spanish-speaking countries, the jaguarundi is called gato colorado, gato moro, león brenero and leoncillo; the Brazilian Portuguese pronunciation of its common English and Portuguese name is. It is called gato-mourisco, eirá, gato-preto, maracajá-preto in Portuguese. Jaguarundi comes from Old Tupi yawaum'di; the jaguarundi has short legs, an elongated body, a long tail. The ears are rounded; the coat is without spots, uniform in color, with, at most, a few faint markings on the face and underside. The coat can be either foxy red to chestnut, it has a length of 53 to 77 centimetres with a 31-to-60 cm-long tail, weighs 3.5 to 9.1 kilograms. The two color morphs were once thought to represent two distinct species: the grey one was called the jaguarundi and the red one was called the eyra.
The jaguarundi occurs from southern Texas and coastal Mexico in the north, through Central and South America east of the Andes, as far south as northern Argentina. In 2015, it has been recorded in Cerro Largo, Uruguay, its habitat is lowland brush areas close to a source of running water, including dry thorn forest to wet grassland. While inhabiting lowlands, it has been reported at elevations as high as 3,200 m, it occurs in dense tropical areas. Jaguarundis have been sighted in Florida since the early 20th century. Here, the species is assumed to have been introduced, but it is not known when the introduction occurred, their presence in Florida is attributed to a writer from Chiefland who at some point imported the animals from their native habitat and released them near his hometown and in other locations across the state. No live or dead specimens are known, but many sightings considered credible by biologists have been reported; the earliest of these occurred in 1907, was followed by various additional sightings throughout the Florida Peninsula from the 1930s through the 1950s.
The first official report was released in 1942. Fewer reliable sightings were reported after that, in 1977 W. T. Neill concluded the population had declined. However, sightings have continued. Jaguarundis have been reported in the coastal area of Alabama since the 1980s, which may be evidence of the Florida population migrating northward; the jaguarundi has been sighted around the Guiana Space Centre in French Guiana. Prior to 2017, the following subspecies were recognised: P. y. yagouaroundi – Geoffroy's jaguarundi P. y. ameghinoi – P. y. cacomitli – Gulf Coast jaguarundi P. y. eyra – eyra P. y. fossata – Guatemalan jaguarundi P. y. melantho – P. y. panamensis – Panamanian jaguarundi P. y. tolteca – Sinaloan jauguarundi As of 2017, the Cat Classification Taskforce of the Cat Specialist Group considers the jaguarundi as member of the genus Herpailurus and does not recognise any subspecies. Jaguarundis are diurnal, being active during the day rather than evenings or night, they prefer to hunt on the ground.
They will eat any small animal they can catch catching a mixture of rodents, small reptiles, ground-feeding birds. They have been observed to kill larger prey, such as rabbits, opossums. Like many other cats, they include a small amount of vegetation and arthropods in their diets. Although they seem to be somewhat more gregarious than many other cats, willing to tolerate the close presence of other members of their species, in the wild, they are encountered alone, suggesting a solitary lifestyle, their home range is variable, depending on the local environment. Like other cats, they scent mark their territory by scratching the ground or nearby branches, head-rubbing and leaving their faeces uncovered, they are shy and reclusive, evidently cautious of traps. Jaguarundis make an unusually wide range of vocalisations, including purrs, yaps, chattering sounds, a bird-like chirp; the timing of the breeding season among jaguarundis is unclear. Oestrus lasts three to five days, marked by the female rolling onto her back and spraying urine.
After a gestation period of 70 to 75 days, the female gives birth to a litter of one to four kittens in a den constructed in a dense thicket, hollow tree, or similar cover. The kittens are born with spots on their undersides; the young are capable of taking solid food at around six weeks, although they begin to play with their mother's food as early as three weeks. Jaguarundis become sexually mature at about two years of age, have lived for up to 10 years in captivity. Jaguarundis are not sought after for their fur, but are suffering decline due to loss of habitat; the Texas Parks an
An ecoregion is an ecologically and geographically defined area, smaller than a bioregion, which in turn is smaller than an ecozone. All three of these are either greater than an ecosystem. Ecoregions cover large areas of land or water, contain characteristic, geographically distinct assemblages of natural communities and species; the biodiversity of flora and ecosystems that characterise an ecoregion tends to be distinct from that of other ecoregions. In theory, biodiversity or conservation ecoregions are large areas of land or water where the probability of encountering different species and communities at any given point remains constant, within an acceptable range of variation. Three caveats are appropriate for all bio-geographic mapping approaches. Firstly, no single bio-geographic framework is optimal for all taxa. Ecoregions reflect the best compromise for as many taxa as possible. Secondly, ecoregion boundaries form abrupt edges. Thirdly, most ecoregions contain habitats. Biogeographic provinces may originate due to various barriers.
Some physical, some climatic and some ocean chemical related. The history of the term is somewhat vague, it had been used in many contexts: forest classifications, biome classifications, biogeographic classifications, etc; the concept of ecoregion of Bailey gives more importance to ecological criteria, while the WWF concept gives more importance to biogeography, that is, distribution of distinct biotas. An ecoregion is a "recurring pattern of ecosystems associated with characteristic combinations of soil and landform that characterise that region". Omernik elaborates on this by defining ecoregions as: "areas within which there is spatial coincidence in characteristics of geographical phenomena associated with differences in the quality and integrity of ecosystems". "Characteristics of geographical phenomena" may include geology, vegetation, hydrology and aquatic fauna, soils, may or may not include the impacts of human activity. There is significant, but not absolute, spatial correlation among these characteristics, making the delineation of ecoregions an imperfect science.
Another complication is that environmental conditions across an ecoregion boundary may change gradually, e.g. the prairie-forest transition in the midwestern United States, making it difficult to identify an exact dividing boundary. Such transition zones are called ecotones. Ecoregions can be categorized using an algorithmic approach or a holistic, "weight-of-evidence" approach where the importance of various factors may vary. An example of the algorithmic approach is Robert Bailey's work for the U. S. Forest Service, which uses a hierarchical classification that first divides land areas into large regions based on climatic factors, subdivides these regions, based first on dominant potential vegetation, by geomorphology and soil characteristics; the weight-of-evidence approach is exemplified by James Omernik's work for the United States Environmental Protection Agency, subsequently adopted for North America by the Commission for Environmental Cooperation. The intended purpose of ecoregion delineation may affect the method used.
For example, the WWF ecoregions were developed to aid in biodiversity conservation planning, place a greater emphasis than the Omernik or Bailey systems on floral and faunal differences between regions. The WWF classification defines an ecoregion as: A large area of land or water that contains a geographically distinct assemblage of natural communities that: Share a large majority of their species and ecological dynamics. According to WWF, the boundaries of an ecoregion approximate the original extent of the natural communities prior to any major recent disruptions or changes. WWF has identified 867 terrestrial ecoregions, 450 freshwater ecoregions across the Earth; the use of the term ecoregion is an outgrowth of a surge of interest in ecosystems and their functioning. In particular, there is awareness of issues relating to spatial scale in the study and management of landscapes, it is recognized that interlinked ecosystems combine to form a whole, "greater than the sum of its parts". There are many attempts to respond to ecosystems in an integrated way to achieve "multi-functional" landscapes, various interest groups from agricultural researchers to conservationists are using the "ecoregion" as a unit of analysis.
The "Global 200" is the list of ecoregions identified by WWF as priorities for conservation. Ecologically based movements like bioregionalism maintain that ecoregions, rather than arbitrarily defined political boundaries, provide a better foundation for the formation and governance of human communities, have proposed ecoregions and watersheds as the basis for bioregional democracy initiatives. Terrestrial ecoregions are land ecoregions, as distinct from marine ecoregions. In this context, terrestrial is used to mean "of land", rather than the more general sense "of Earth". WWF ecologists divide the land surface of the Earth into 8 major ecozones containing 867 smaller terrestrial ecoregions; the WWF effort is a synthesis of
The harpy eagle is a neotropical species of eagle. It is called the American harpy eagle to distinguish it from the Papuan eagle, sometimes known as the New Guinea harpy eagle or Papuan harpy eagle, it is the largest and most powerful raptor found in the rainforest, among the largest extant species of eagles in the world. It inhabits tropical lowland rainforests in the upper canopy layer. Destruction of its natural habitat has caused it to vanish from many parts of its former range, it is nearly extirpated in Central America. In Brazil, the harpy eagle is known as royal-hawk; the harpy eagle was first described by Linnaeus in his Systema Naturae in 1758 as Vultur harpyja, after the mythological beast harpy. The only member of the genus Harpia, the harpy eagle is most related to the crested eagle and the New Guinea harpy eagle, the three composing the subfamily Harpiinae within the large family Accipitridae. Thought to be related, the Philippine eagle has been shown by DNA analysis to belong elsewhere in the raptor family, as it is related to the Circaetinae.
The species name harpyja and the word harpy in the common name harpy eagle both come from Ancient Greek harpyia. They refer to the Harpies of Ancient Greek mythology; these were wind spirits that took the dead to Hades, were said to have a body like an eagle and the face of a human. The upper side of the harpy eagle is covered with slate-black feathers, the underside is white, except for the feathered tarsi, which are striped black. A broad black band across the upper breast separates the gray head from the white belly; the head is pale grey, is crowned with a double crest. The upper side of the tail is black with three gray bands, while the underside of it is black with three white bands; the iris is gray or brown or red, the cere and bill are black or blackish and the tarsi and toes are yellow. The plumage of males and females are identical; the tarsus is up to 13 cm long. Female harpy eagles weigh 6 to 9 kg. One source states. An exceptionally large captive female, "Jezebel", weighed 12.3 kg. Being captive, this large female may not be representative of the weight possible in wild harpy eagles due to differences in the food availability.
The male, in comparison, weighs only about 4 to 4.8 kg. Harpy eagles have a wingspan of 176 to 224 cm. Among the standard measurements, the wing chord measures 54–63 cm, the tail measures 37–42 cm, the tarsus is 11.4–13 cm long, the exposed culmen from the cere is 4.2 to 6.5 cm. It is sometimes cited as the largest eagle alongside the Philippine eagle, somewhat longer on average, the Steller's sea eagle, heavier on average; the wingspan of the harpy eagle is small, an adaptation that increases maneuverability in forested habitats and is shared by other raptors in similar habitats. The wingspan of the harpy eagle is surpassed by several large eagles who live in more open habitats, such as those in the Haliaeetus and Aquila genera; the extinct Haast's eagle was larger than all extant eagles, including the harpy. This species is silent away from the nest. There, the adults give a penetrating, melancholy scream, with the incubating males' call described as "whispy screaming or wailing"; the females' calls while incubating are lower-pitched.
While approaching the nest with food, the male calls out "rapid chirps, goose-like calls, occasional sharp screams". Vocalization in both parents decreases as the nestlings age; the nestlings call chi-chi-chi...chi-chi-chi-chi in alarm in response to rain or direct sunlight. When humans approach the nest, the nestlings have been described as uttering croaks and whistles. Rare throughout its range, the harpy eagle is found from Mexico, through Central America and into South America to as far south as Argentina. In rainforests, they live in the emergent layer; the eagle is most common in Brazil. With the exception of some areas of Panama, the species is extinct in Central America, subsequent to the logging of much of the rainforest there; the harpy eagle inhabits tropical lowland rainforests and may occur within such areas from the canopy to the emergent vegetation. They occur below an elevation of 900 m, but have been recorded at elevations up to 2,000 m. Within the rainforest, they hunt in the canopy or sometimes on the ground, perch on emergent trees looking for prey.
They do not occur in disturbed areas, but visit semiopen forest/pasture mosaic in hunting forays. Harpies, can be found flying over forest borders in a variety of habitats, such as cerrados, buriti palm stands, cultivated fields, cities, they have been found in areas. Adults are near or at the top of a food chain and are preyed on. However, two adult eagles that were being released into the wild as part of a reintroduction program were taken by a jaguar and the much smaller ocelot Its main prey are tree-dwelling mammals and a majority of the diet has been shown to focus on sloths and monkeys. Research conducted by Aguiar-Silva between 2003 and 2005 in a nesting site in Parintins, Brazil, collected remains from prey offered to the nestling by its parents and after sor
Plumage refers both to the layer of feathers that cover a bird and the pattern and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, there can be different colour morphs; the placement of feathers on a bird is not haphazard, but rather emerge in organized, overlapping rows and groups, these feather tracts are known by standardized names. Most birds moult twice a year, resulting in a basic plumage. Many ducks and some other species such as the red junglefowl have males wearing a bright nuptial plumage while breeding and a drab eclipse plumage for some months afterward; the painted bunting's juveniles have two inserted moults in their first autumn, each yielding plumage like an adult female. The first starts a few days after fledging replacing the juvenile plumage with an auxiliary formative plumage. Abnormal plumages include a variety of conditions. Albinism, total loss of colour, is rare; some species are colour polymorphic, having two or more colour variants.
A few species have special types of polymorphism, as in the male ruff which has an assortment of different colours around the head and neck in the breeding season only. Hen feathering is an inherited plumage character in domestic fowl controlled by a single gene. Plumology is the name for the science, associated with the study of feathers. All species of birds moult at least annually after the breeding season, known as the pre-basic moult; this resulting covering of feathers, which will last either until the next breeding season or until the next annual moult, is known as the basic plumage. Many species undertake another moult prior to the breeding season known as the pre-alternate moult, the resulting breeding plumage being known as the alternate plumage or nuptial plumage; the alternate plumage is brighter than the basic plumage, for the purposes of sexual display, but may be cryptic to hide incubating birds that might be vulnerable on the nest. The Humphrey-Parkes terminology requires some attention to detail to name moults and plumages correctly.
Many ducks have colourful plumage, exhibiting strong sexual dimorphism. However, they moult into a dull plumage after breeding in mid-summer; this drab, female-like appearance is called eclipse plumage. When they shed feathers to go into eclipse, the ducks become flightless for a short period of time; some duck species remain in eclipse for one to three months in the late summer and early fall, while others retain the cryptic plumage until the next spring when they undergo another moult to return to their breeding plumage. Although found in the Anatidae, a few other species, including related red junglefowl, most fairywrens and some sunbirds have an eclipse plumage. In the superb and splendid fairywrens old males may moult from one nuptial plumage to another whereas in the red-backed and white-winged fairywrens, males do not acquire nuptial plumage until four years of age – well after they become sexually mature and indeed longer than the vast majority of individuals live. In contrast to the ducks, males of hummingbirds and most lek-mating passerines – like the Guianan cock-of-the-rock or birds of paradise – retain their exuberant plumage and sexual dimorphism at all times, moulting as ordinary birds do once annually.
There are hereditary as well as non-hereditary variations in plumage that are rare and termed as abnormal or aberrant plumages. Melanism refers to an excess of dark colours. Erythromelanism or erythrism is the result of excessive reddish brown erythromelanin deposition in feathers that lack melanin. Melanin of different forms combine with xanthophylls to produce colour mixtures and when this combination is imbalanced it produces colour shifts that are termed as schizochroisms. A reduction in eumelanin leads to non-eumelanin schizochroism with an overall fawn plumage while a lack of phaeomelanin results in grey coloured non-phaeomelanin schizochroism. Carotenism refers to abnormal distribution of carotenoid pigments; the term "dilution" is used for situations. Dilution occurs in normal plumage, but may in addition occur as an aberration. In some birds – many true owls, some nightjars and a few cuckoos being known examples – there is colour polymorphism; this means that two or more colour variants are numerous within their populations during all or at least most seasons and plumages.
Other cases of natural polymorphism are of various kinds. Albinism in birds is rare, occurring to any extent in one in 1800 individuals, it involves loss of colour in all par
The Paraná River is a river in south Central South America, running through Brazil and Argentina for some 4,880 kilometres. It is second in length only to the Amazon River among South American rivers; the name Paraná is an abbreviation of the phrase "para rehe onáva", which comes from the Tupi language and means "like the sea". It merges first with the Paraguay River and farther downstream with the Uruguay River to form the Río de la Plata and empties into the Atlantic Ocean; the first European to go up the Paraná River was the Venetian explorer Sebastian Cabot, in 1526, while working for Spain. The course is formed at the confluence of the Rio Grande rivers in southern Brazil. From the confluence the river flows in a southwestern direction for about 619 km before encountering the city of Saltos del Guaira, Paraguay; this was once the location of the Guaíra Falls (Sete Quedas waterfalls, where the Paraná fell over a series of seven cascades. This natural feature was said to rival the world-famous Iguazu Falls to the south.
The falls were flooded, however, by the construction of the Itaipu Dam, which began operating in 1984. For the next 200 km the Paraná flows southward and forms a natural boundary between Paraguay and Brazil until the confluence with the Iguazu River. Shortly upstream from this confluence, the river is dammed by the Itaipu Dam, the second largest hydroelectric power plant in the world, creating a massive, shallow reservoir behind it. After merging with the Iguazu, the Paraná becomes the natural border between Paraguay and Argentina. Overlooking the Paraná River from Encarnación, across the river, is downtown Posadas, Argentina; the river continues its general southward course for about 468 km before making a gradual turn to the west for another 820 km, encounters the Paraguay River, the largest tributary along the course of the river. Before this confluence the river passes through a second major hydroelectric project, the Yaciretá Dam, a joint project between Paraguay and Argentina; the massive reservoir formed by the project has been the source of a number of problems for people living along the river, most notably the poorer merchants and residents in the low-lying areas of Encarnación, a major city on the southern border of Paraguay.
River levels rose upon completion of the dam, flooding out large sections of the city's lower areas. From the confluence with the Paraguay River, the Paraná again turns to the south for another 820 km through Argentina, making a slow turn back to the east near the city of Rosario for the final stretch of less than 500 km before merging with the Uruguay River to form the Río de la Plata; this flows into the Atlantic Ocean. During the part of its course downstream from the city of Diamante, Entre Ríos, it splits into several arms and it forms the Paraná Delta. Together with its tributaries, the Rio Paraná forms a massive drainage basin that encompasses much of the southcentral part of South America including all of Paraguay, much of southern Brazil, northern Argentina, the southeastern part of Bolivia. If the Uruguay River is counted as a tributary to the Paraná, this watershed extends to cover most of Uruguay as well; the volume of water flowing into the Atlantic Ocean through the Río de la Plata equals the volume at the Mississippi River delta.
This watershed contains a number of large cities, including São Paulo, Buenos Aires, Asunción, Brasília, La Plata. The Paraná and its tributaries provide a source of income and of daily sustenance for fishermen who live along its banks; some of the species of fish are commercially important, they are exploited for heavy internal consumption or for export. The Parana River delta ranks as one of the world's greatest bird-watching destinations. Much of the length of the Paraná is navigable, the river serves as an important waterway linking inland cities in Argentina and Paraguay with the ocean, providing deepwater ports in some of these cities; the construction of enormous hydroelectric dams along the river's length has blocked its use as a shipping corridor to cities further upstream, but the economic impact of those dams offsets this. The Yacyretá Dam and the Itaipu Dam on the Paraguay border have made the small undeveloped nation of Paraguay the world's largest exporter of hydroelectric power.
Due to its use for oceangoing ships, measurements of the water tables extend back to 1904. The data correlates with the solar cycle; the course of the Paraná is crossed by the following bridges, beginning upstream: Tributaries of the Río de la Plata Paraná River steamers Information and a map of the Paraná's watershed "Paraná". New International Encyclopedia. 1905
International Union for Conservation of Nature
The International Union for Conservation of Nature is an international organization working in the field of nature conservation and sustainable use of natural resources. It is involved in data gathering and analysis, field projects and education. IUCN's mission is to "influence and assist societies throughout the world to conserve nature and to ensure that any use of natural resources is equitable and ecologically sustainable". Over the past decades, IUCN has widened its focus beyond conservation ecology and now incorporates issues related to sustainable development in its projects. Unlike many other international environmental organisations, IUCN does not itself aim to mobilize the public in support of nature conservation, it tries to influence the actions of governments and other stakeholders by providing information and advice, through building partnerships. The organization is best known to the wider public for compiling and publishing the IUCN Red List of Threatened Species, which assesses the conservation status of species worldwide.
IUCN has a membership of over 1400 non-governmental organizations. Some 16,000 scientists and experts participate in the work of IUCN commissions on a voluntary basis, it employs 1000 full-time staff in more than 50 countries. Its headquarters are in Switzerland. IUCN has observer and consultative status at the United Nations, plays a role in the implementation of several international conventions on nature conservation and biodiversity, it was involved in establishing the World Wide Fund for Nature and the World Conservation Monitoring Centre. In the past, IUCN has been criticized for placing the interests of nature over those of indigenous peoples. In recent years, its closer relations with the business sector have caused controversy. IUCN was established in 1948, it was called the International Union for the Protection of Nature and the World Conservation Union. Establishment IUCN was established on 5 October 1948, in Fontainebleau, when representatives of governments and conservation organizations signed a formal act constituting the International Union for the Protection of Nature.
The initiative to set up the new organisation came from UNESCO and from its first Director General, the British biologist Julian Huxley. The objectives of the new Union were to encourage international cooperation in the protection of nature, to promote national and international action and to compile and distribute information. At the time of its founding IUPN was the only international organisation focusing on the entire spectrum of nature conservation Early years: 1948–1956 IUPN started out with 65 members, its secretariat was located in Brussels. Its first work program focused on saving species and habitats and applying knowledge, advancing education, promoting international agreements and promoting conservation. Providing a solid scientific base for conservation action was the heart of all activities. IUPN and UNESCO were associated, they jointly organized the 1949 Conference on Protection of Nature. In preparation for this conference a list of gravely endangered species was drawn up for the first time, a precursor of the IUCN Red List of Threatened Species.
In the early years of its existence IUCN depended entirely on UNESCO funding and was forced to temporarily scale down activities when this ended unexpectedly in 1954. IUPN was successful in engaging prominent scientists and identifying important issues such as the harmful effects of pesticides on wildlife but not many of the ideas it developed were turned into action; this was caused by unwillingness to act on the part of governments, uncertainty about the IUPN mandate and lack of resources. In 1956, IUPN changed its name to International Union for Conservation of Nature and Natural Resources. Increased profile and recognition: 1956–1965 In the 1950s and 1960s Europe entered a period of economic growth and formal colonies became independent. Both developments had impact on the work of IUCN. Through the voluntary involvement of experts in its Commissions IUCN was able to get a lot of work done while still operating on a low budget, it established links with the Council of Europe. In 1961, at the request of United Nations Economic and Social Council, the United Nations Economic and Social Council, IUCN published the first global list of national parks and protected areas which it has updated since.
IUCN's best known publication, the Red Data Book on the conservation status of species, was first published in 1964. IUCN began to play a part in the development of international treaties and conventions, starting with the African Convention on the Conservation of Nature and Natural Resources. Environmental law and policy making became a new area of expertise. Africa was the focus of many of the early IUCN conservation field projects. IUCN supported the ‘Yellowstone model’ of protected area management, which restricted human presence and activity in order to protect nature. IUCN and other conservation organisations were criticized for protecting nature against people rather than with people; this model was also applied in Africa and played a role in the decision to remove the Maasai people from Serengeti National Park and the Ngorongoro Conservation Area. To establish a stable financial basis for its work, IUCN participated in setting up the World Wildlife Fund
Mammals are vertebrate animals constituting the class Mammalia, characterized by the presence of mammary glands which in females produce milk for feeding their young, a neocortex, fur or hair, three middle ear bones. These characteristics distinguish them from reptiles and birds, from which they diverged in the late Triassic, 201–227 million years ago. There are around 5,450 species of mammals; the largest orders are the rodents and Soricomorpha. The next three are the Primates, the Cetartiodactyla, the Carnivora. In cladistics, which reflect evolution, mammals are classified as endothermic amniotes, they are the only living Synapsida. The early synapsid mammalian ancestors were sphenacodont pelycosaurs, a group that produced the non-mammalian Dimetrodon. At the end of the Carboniferous period around 300 million years ago, this group diverged from the sauropsid line that led to today's reptiles and birds; the line following the stem group Sphenacodontia split off several diverse groups of non-mammalian synapsids—sometimes referred to as mammal-like reptiles—before giving rise to the proto-mammals in the early Mesozoic era.
The modern mammalian orders arose in the Paleogene and Neogene periods of the Cenozoic era, after the extinction of non-avian dinosaurs, have been among the dominant terrestrial animal groups from 66 million years ago to the present. The basic body type is quadruped, most mammals use their four extremities for terrestrial locomotion. Mammals range in size from the 30–40 mm bumblebee bat to the 30-meter blue whale—the largest animal on the planet. Maximum lifespan varies from two years for the shrew to 211 years for the bowhead whale. All modern mammals give birth to live young, except the five species of monotremes, which are egg-laying mammals; the most species-rich group of mammals, the cohort called placentals, have a placenta, which enables the feeding of the fetus during gestation. Most mammals are intelligent, with some possessing large brains, self-awareness, tool use. Mammals can communicate and vocalize in several different ways, including the production of ultrasound, scent-marking, alarm signals and echolocation.
Mammals can organize themselves into fission-fusion societies and hierarchies—but can be solitary and territorial. Most mammals are polygynous. Domestication of many types of mammals by humans played a major role in the Neolithic revolution, resulted in farming replacing hunting and gathering as the primary source of food for humans; this led to a major restructuring of human societies from nomadic to sedentary, with more co-operation among larger and larger groups, the development of the first civilizations. Domesticated mammals provided, continue to provide, power for transport and agriculture, as well as food and leather. Mammals are hunted and raced for sport, are used as model organisms in science. Mammals have been depicted in art since Palaeolithic times, appear in literature, film and religion. Decline in numbers and extinction of many mammals is driven by human poaching and habitat destruction deforestation. Mammal classification has been through several iterations since Carl Linnaeus defined the class.
No classification system is universally accepted. George Gaylord Simpson's "Principles of Classification and a Classification of Mammals" provides systematics of mammal origins and relationships that were universally taught until the end of the 20th century. Since Simpson's classification, the paleontological record has been recalibrated, the intervening years have seen much debate and progress concerning the theoretical underpinnings of systematization itself through the new concept of cladistics. Though field work made Simpson's classification outdated, it remains the closest thing to an official classification of mammals. Most mammals, including the six most species-rich orders, belong to the placental group; the three largest orders in numbers of species are Rodentia: mice, porcupines, beavers and other gnawing mammals. The next three biggest orders, depending on the biological classification scheme used, are the Primates including the apes and lemurs. According to Mammal Species of the World, 5,416 species were identified in 2006.
These were grouped into 153 families and 29 orders. In 2008, the International Union for Conservation of Nature completed a five-year Global Mammal Assessment for its IUCN Red List, which counted 5,488 species. According to a research published in the Journal of Mammalogy in 2018, the number of recognized mammal species is 6,495 species included 96 extinct; the word "mammal" is modern, from the scientific name Mammalia coined by Carl Linnaeus in 1758, derived from the Latin mamma. In an influential 1988 paper, Timothy Rowe defined Mammalia phylogenetically as the crown group of mammals, the clade consisting of the most recent common ancestor of living monotremes and therian m