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41-488: The malleefowl ( Leipoa ocellata ) is a stocky ground-dwelling Australian bird about the size of a domestic chicken (to which it is distantly related). It is notable for the large nesting mounds constructed by the males and lack of parental care after the chicks hatch. It is the only living representative of the genus Leipoa , though the extinct giant malleefowl was a close relative. Malleefowl are shy, wary, solitary birds that usually fly only to escape danger or reach

82-502: A National IBA Conservation Strategy, whereas in others protection is completely lacking. In 1985, following a specific request from the European Economic Community , Birdlife International drew up a list of sites to be protected as a matter of priority. In 1989, a repertoire of IBAs of Europe was released. At first the official name of this type of site was Important Bird Area , hence the acronym IBA, then at

123-695: 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 Important bird area IBA

164-473: 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

205-442: 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

246-634: A group of warm-blooded vertebrates constituting the class Aves ( Latin: [ˈaveːs] ), characterised by feathers , toothless beaked jaws, the laying of hard-shelled eggs, 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;

287-401: A season, she commonly lays 250% of her own weight. Clutch size varies greatly between birds and with rainfall. Incubation time depends on temperature and can be between about 50 and almost 100 days. Hatchlings use their strong feet to break out of the egg, then lie on their backs and scratch their way to the surface, struggling hard for 5 to 10 minutes to gain 3 to 15 cm (1 to 6 in) at

328-406: 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

369-422: A structure as older birds. They are thought to mate for life, and although the males stay nearby to defend the nests for nine months of the year, they can wander at other times, not always returning to the same territory afterwards. The female lays a clutch of two or three to over 30 large, thin-shelled eggs, mostly about 15; usually about a week apart. Each egg weighs about 10% of the female's body weight, and over

410-401: A time, and then resting for an hour or so before starting again. Reaching the surface takes between 2 and 15 hours. Chicks pop out of the nesting material with little or no warning, with eyes and beaks tightly closed, then immediately take a deep breath and open their eyes, before freezing motionless for as long as 20 minutes. The chick then quickly emerges from the hole and rolls or staggers to

451-717: 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)

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492-402: A tree to roost in. Although very active, they are seldom seen as they freeze if disturbed, relying on their intricately patterned plumage to render them invisible, or else fade silently and rapidly into the undergrowth (flying away only if surprised or chased). They have many tactics to run away from predators . Pairs occupy a territory, but usually roost and feed apart; their social behaviour

533-540: 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

574-429: 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

615-461: Is known, estimated or thought to hold a population of a species categorized by the IUCN Red List as Critically Endangered , Endangered or Vulnerable . In general, the regular presence of a Critical or Endangered species, irrespective of population size, at a site may be sufficient for a site to qualify as an IBA. For Vulnerable species, the presence of more than threshold numbers at a site

656-464: Is located at Ongerup , Western Australia , on the road between Albany and Esperance . The centre opened in February 2007 and is intended to provide a focal point for education about the malleefowl and the conservation of the species. It has a permanent exhibition and a large aviary containing a pair of malleefowl. The centre collects reported sightings of the malleefowl. Aves Birds are

697-488: Is necessary to trigger selection. The site forms one of a set selected to ensure that all restricted-range species of an Endemic Bird Area (EBA) or a Secondary Area (SA) are present in significant numbers in at least one site and preferably more. The site forms one of a set selected to ensure adequate representation of all species restricted to a given biome, both across the biome as a whole and for all of its species in each range state. The assessment by expert individuals

738-503: 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

779-530: Is sufficient to allow regular mating during the season and little else. In winter, the male selects an area of ground, usually a small, open space between the stunted trees of the mallee , and scrapes a depression about 3 m (9.8 ft) across and just under 1 m (3.3 ft) deep in the sandy soil by raking backwards with his feet. In late winter and early spring, he begins to collect organic material to fill it with, scraping sticks, leaves, and bark into windrows for up to 50 m (160 ft) around

820-516: 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,

861-535: 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

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902-722: 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

943-669: 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

984-552: The BirdLife World Congress held in Canada in 2014 it was decided to adopt the name Important Bird and Biodiversity Area , without changing the acronym. IBAs are determined by an internationally agreed set of criteria. Specific IBA thresholds are set by regional and national governing organizations. To be listed as an IBA, a site must satisfy at least one of the following rating criteria: The site qualifies if it

1025-428: 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

1066-490: The base of the mound, disappearing into the scrub within moments. Within an hour, it will be able to run reasonably well; it can flutter for a short distance and run very fast within two hours, and despite not having yet grown tail feathers , it can fly strongly within a day. Chicks have no contact with adults or other chicks; they tend to hatch one at a time, and birds of any age ignore one another except for mating or territorial disputes. It occupies semiarid mallee scrub on

1107-509: 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

1148-665: 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

1189-498: The excavation of the egg chamber, and the timing varies with temperature and rainfall . The female usually lays between September and February, provided enough rain has fallen to start organic decay of the litter. The male continues to maintain the nest mound, gradually adding more soil to the mix as the summer approaches (presumably to regulate the temperature). Males usually build their first mound (or take over an existing one) in their fourth year, but tend not to achieve as impressive

1230-451: 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

1271-601: The fringes of the relatively fertile areas of southern Australia, where it is now reduced to three separate populations: the Murray – Murrumbidgee basin, west of Spencer Gulf along the fringes of the Simpson Desert , and the semiarid fringe of Western Australia 's fertile southwest corner. Several important bird areas across southern mainland Australia have been identified by BirdLife International as being significant for malleefowl conservation: Across its range ,

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1312-493: The hole, and building it into a nest mound, which usually rises to about 0.6 m (2.0 ft) above ground level. The amount of litter in the mound varies; it may be almost entirely organic material, mostly sand, or any ratio in between. After rain, he turns and mixes the material to encourage decay, and if conditions allow, digs an egg chamber in August (the last month of the southern winter). The female sometimes assists with

1353-401: The malleefowl is considered to be threatened. Predation from the introduced red fox is a factor, but the critical issues are changed fire regimens and the ongoing destruction and habitat fragmentation . Like the southern hairy-nose wombat , it is particularly vulnerable to the increasing frequency and severity of drought that has resulted from climate change . Before the arrival of Europeans,

1394-667: The malleefowl was found over huge swaths of Australia. The malleefowl is classified as vulnerable on the International Union for Conservation of Nature Red List. Malleefowl are listed as vulnerable on the Australian Environment Protection and Biodiversity Conservation Act 1999 . Its conservation status has varied over time, and also varies from state to state within Australia. For example: The Yongergnow Australian Malleefowl Centre

1435-523: 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

1476-402: 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

1517-536: 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

1558-452: 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

1599-551: 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

1640-745: Was developed and sites are identified by BirdLife International . There are over 13,000 IBAs worldwide. These sites are small enough to be entirely conserved and differ in their character, habitat or ornithological importance from the surrounding habitat. In the United States the program is administered by the National Audubon Society . Often IBAs form part of a country's existing protected area network, and so are protected under national legislation. Legal recognition and protection of IBAs that are not within existing protected areas varies within different countries. Some countries have

1681-466: 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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