Hooрe

The Hoopoe (pronounced /ˈhuːpuː/), Upupa epops, is a colourful bird that is found across Afro-Eurasia, notable for its distinctive 'crown' of feathers. It is the only extant species in the family Upupidae. One insular species, the Giant Hoopoe of Saint Helena, is extinct, and the Madagascar subspecies of the Hoopoe is sometimes elevated to a full species.
Taxonomy

The Hoopoe is classified in the Coraciiformes clade, a group that also includes kingfishers, bee-eaters, rollers, and woodhoopoes (forming a clade with this one according to Hackett et al. (2008)[2]). A close relationship between the Hoopoe and the woodhoopoes is also supported by the shared and unique nature of their stapes.[3] In the Sibley-Ahlquist taxonomy, the Hoopoe is separated from the Coraciiformes as a separate order, the Upupiformes. Some authorities place the woodhoopoes in the Upupiformes as well.[4]

The fossil record of the hoopoes is very incomplete, with the earliest fossil coming from the Quaternary.[5] The fossil record of their relatives is older, with fossil woodhoopoes dating back to the Miocene and those of an extinct related family, the Messelirrisoridae, dating from the Eocene.[4]

It is the only extant member of its family, although some treatments consider some of the subspecies as separate species. Several authors have separated the Madagascan subspecies (U. e. marginata) as a separate species, and also the resident African form U. e. africana. The morphological differences between the most commonly split subspecies, U. e. marginata, and the other subspecies are minor, and only U. e. marginata has distinctly different vocalisations.[6] One accepted separate species, the Giant Hoopoe, U. antaios, lived on the island of St Helena but became extinct in the sixteenth century, presumably due to introduced species.[5]

The genus Upupa was created by Linnaeus in his Systema naturae in 1758. It then included three other species with long curved bills:[7]
U. eremita (now Geronticus eremita), the Northern Bald Ibis
U. pyrrhocorax (now Pyrrhocorax pyrrhocorax), the Red-billed Chough
U. paradisea
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Subspecies

Nine subspecies of Hoopoe are recognised by the Kristin 2001 (in the Handbook of the Birds of the World), with these subspecies varying mostly in size and the depth of colour in the plumage. Two further subspecies have been proposed, U. e. minor in South Africa and U. e. orientalis in north western India.Subspecies[6] Breeding range[6] Distinctive features[6]
U. e. epops
Linnaeus, 1758 NW Africa, Canary Islands, and from Europe through to south central Russia, north west China and south to north west India. Nominate
U. e. major
C.L. Brehm, 1855 North east Africa Larger than nominate, longer billed, narrower tailband, greyer upperparts
U. e. senegalensis
Swainson, 1913 Senegal to Ethiopia Smaller than nominate, shorter winged
U. e. waibeli
Reichenow, 1913 Cameroon through to north Kenya As U. e. senegalensis but darker plumage and more white on wings
U. e. africana
Bechstein, 1811 Central Africa to South Africa Much more rufous than nominate
U. e. marginata
Cabanis & Heine, 1860 Madagascar Larger, much more pale than U. e. africana
U. e. saturata
Lönnberg, 1909 Japan, Siberia to Tibet and south China As nominate, greyer mantle, less pink below
U. e. ceylonensis
Reichenbach, 1853 Pakistan, India and Sri Lanka Smaller than nominate, more rufous overall, no white in crest
U. e. longirostris
Jerdon, 1862 South east Asia Larger than nominate, pale

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Distribution, habitat and migration

The Hoopoe is widespread in Europe, Asia, and North Africa, Sub-Saharan Africa and Madagascar.[6] Most European and north Asian birds migrate to the tropics in winter.[8] In contrast the African populations are sedentary year-round. The species has been a vagrant in Alaska;[9] U. e. saturata was recorded as being seen there in 1975 in the Yukon Delta.[10] Hoopoes have been known to breed north of their European range,[11] and in southern England during warm, dry summers that provide plenty of grasshoppers and similar insects,[12] although as of the early 1980s northern European populations were reported to be in the decline possibly due to changes in climate.[11]

The Hoopoe has two basic requirements in its habitat; bare or lightly vegetated ground on which to forage and vertical surfaces with cavities (such as trees, cliffs or even walls, nestboxes, haystacks, and abandoned burrows[11]) in which to nest. These requirements can be provided in a wide range of ecosystems and as a consequence they inhabit a wide range of habitats from heathland, wooded steppes, savannas and grasslands, as well as glades inside forests. The Madagascar subspecies also makes use of more dense primary forest. The modification of natural habitats by humans for various agricultural purposes has led to them becoming common in olive groves, orchards, vineyards, parkland and farmland, although they are less common and declining in intensively farmed areas.[6] Hunting is of concern in southern Europe and Asia.[10]

Hoopoes make seasonal movements in response to rain in some regions such as in Ceylon and in the Western Ghats.[13]
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Description

The muscles of the head allow the Hoopoe's bill to be opened when it is inserted into the ground

The Hoopoe is a medium sized bird, 25–32 cm (9.8-12.6 in) long, with a 44–48 cm (17.3–19 in) wingspan weighing 46-89 g (1.6-3.1 oz). The species is highly distinctive, with a long, thin tapering bill that is black with a fawn base. The strengthened musculature of the head allows the bill to be opened when probing inside the soil. The hoopoe has broad and rounded wings capable of strong flight; these are larger in the northern migratory subspecies. The Hoopoe has a characteristic undulating flight, which is like that of a giant butterfly, caused by the wings half closing at the end of each beat or short sequence of beats.[6]

The song is a trisyllabic "oop-oop-oop", which gives rise to its English and scientific names.

A hoopoe sunbathing, on Lanzarote.
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Behaviour

In what was long thought to be a defensive posture, Hoopoes sunbathe by spreading out their wings and tail low against the ground and tilting their head up; they often fold their wings and preen halfway through.[14] The Hoopoe also enjoys taking dust and sand baths.[15]
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Diet and feeding

The diet of the Hoopoe is mostly composed of insects, although small reptiles and frogs as well as some plant matter such as seeds and berries are sometimes taken as well. It is a solitary forager which typically feeds on the ground. More rarely they will feed in the air, in pursuit of numerous swarming insects, where their strong and rounded wings make them fast and manoeuvrable. More commonly their foraging style is to stride on relatively open ground and periodically pause to probe the ground with the full length of their bill. Insect larvae, pupae and mole crickets are detected by the bill and either extracted or dug out with the strong feet. In addition to feeding in soil Hoopoes will feed on insects on the surface, as well as probing into piles of leaves and even using the bill to lever large stones and flake off bark. Common diet items include crickets, locusts, beetles, earwigs, cicadas, ant lions, bugs and ants. These can range from 10 to 150 mm in length, with the preferred size of prey being around 20–30 mm. Larger prey items are beaten against the ground or a preferred stone in order to kill them and remove indigestible body parts such as wings and legs.[6]
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Breeding

The Hoopoe is monogamous, although the pair bond apparently only lasts for a single season. They are also territorial, with the male calling frequently to advertise his ownership of the territory. Chases and fights between rival males (and sometimes females) are common and can be brutal.[6] Birds will try to stab rivals with their bills, and individuals are occasionally blinded in fights.[16] The nest is in a hole in a tree or wall, with a narrow entrance;[15] it may be unlined or various scraps may be collected.[11] The female alone is responsible for incubating the eggs. Clutch size varies with location, with northern hemisphere birds laying more eggs than those in the southern hemisphere and birds in higher latitudes having larger clutches than those closer to the equator. In central and northern Europe and Asia the clutch size is around 12, whereas it is between four in the tropics and seven in the subtropics. The eggs are round and milky blue on laying but quickly discolour in the increasingly dirty nest.[6] They weigh 4.5 grams.[14] A replacement clutch is possible.[11]

The Hoopoes have well-developed anti-predators defences in the nest. The uropygial gland of the incubating and brooding female is quickly modified to produce a foul-smelling liquid, and the glands of nestlings do so as well. These secretions are rubbed into the plumage. The secretion, which smells like rotting meat, is thought to help deter predators, as well as deter parasites and possibly act as an antibacterial agent.[17] The secretions stop soon before the young leave the nest.[14] In addition to this secretion nestlings are able to direct streams of faeces at nest intruders from the age of six days, and will also hiss at intruders in a snake like fashion.[6] The young also strike with their bill or with one wing.[14]

The incubation period for the species is between 15 and 18 days. During incubation the female is fed by the male. The incubation period begins as soon as the first egg is laid, so the chicks are born asynchronously. The chicks hatch with a covering of downy feathers, by around day days feather quills emerge which become adult feathers. The chicks are brooded by the female for between 9 to 14 days.[6] The female later joins the male in the task of bringing food.[15] The young fledge in 26 to 29 days and remain with the parents for about a week.[11]

Facts about pets. Parrots

Hi, guys! Today I decided to tell you about my fav pet-bird parrots

Parrots, also known as psittacines (pronounced /ˈsɪtəsaɪnz/),[2][3] are birds of the roughly 372 species in 86 genera that make up the order Psittaciformes,[4] found in most warm and tropical regions. The order is subdivided in three families: the Psittacidae ('true' parrots), the Cacatuidae (cockatoos) and the Strigopidae (New Zealand parrots).[5] Parrots have a pan-tropical distribution with several species inhabiting the temperate Southern Hemisphere as well. The greatest diversity of parrots is found in South America and Australasia.

Characteristic features of parrots include a strong curved bill, an upright stance, strong legs, and clawed zygodactyl feet. Most parrots are predominantly green, with other bright colors, and some species are multi-colored. Cockatoo species range from mostly white to mostly black, and have a mobile crest of feathers on the top of their heads. Most parrots are monomorphic or minimally sexually dimorphic. They are the most variably sized bird order in terms of length.

The most important components of most parrots' diets are seeds, nuts, fruit, buds and other plant material. A few species also eat insects and small animals, and the lories and lorikeets are specialised to feed on nectar from flowers, and soft fruits. Almost all parrots nest in tree holes (or nest boxes in captivity), and lay white eggs from which emerge altricial (helpless) young.

Parrots, along with ravens, crows, jays and magpies, are some of the most intelligent birds, and the ability of some parrot species to imitate human voices enhances their popularity as pets. Trapping of wild parrots for the pet trade, as well as other hunting, habitat loss and competition from invasive species, have diminished wild populations, and parrots have been subjected to more exploitation than any other group of birds.[6] Recent conservation measures to conserve the habitats of some of the high-profile charismatic parrot species has also protected many of the less charismatic species living in the ecosystem.

Researchers are still unsure about the origins of parrots. The diversity among Psittaciformes in South America and Australasia suggests that the order may have come from Gondwanaland, with the center found in Australasia.[8] The scarcity of the bird's fossil record, however, may cause difficulty in proving this.

A single 1002 mm fragment from a large lower bill (UCMP 143274), found in deposits from the Lance Creek Formation in Niobrara County, Wyoming, is thought to be the oldest parrot fossil and is presumed to have originated from the Late Cretaceous period, which makes it about 70 million years old.[9] There have been studies, though, that establishes that this fossil is almost certainly not from a bird, but from a caenagnathid theropod or a non-avian dinosaur with a birdlike beak.[10][11]

It is now generally assumed that the Psittaciformes or their common ancestors with a number of related bird orders were present somewhere in the world around the Cretaceous–Tertiary extinction event, some 65 mya (million years ago). If so, they probably had not evolved their morphological autapomorphies yet, but were generalized arboreal birds, roughly similar (though not necessarily closely related) to today's potoos or frogmouths (see also Palaeopsittacus below).

Europe is the origin of the first presumed parrot fossils. The first is a wingbone of Mopsitta tanta, uncovered in Denmark and dated to 54 mya (million years ago).[12] The climate at this time was tropical, consistent with the Paleocene-Eocene Thermal Maximum.

Later fossils date from the Eocene, starting around 50 mya. Several fairly complete skeletons of parrot-like birds have been found in England and Germany.[13] Some uncertainty remains, but on the whole it seems more likely that these are not direct ancestors of the modern parrots, but related lineages which evolved in the Northern Hemisphere but have since died out. These are probably not "missing links" between ancestral and modern parrots, but rather psittaciform lineages that evolved parallel to true parrots and cockatoos and had their own peculiar autapomorphies:
Psittacopes (Early/Middle Eocene of Geiseltal, Germany) – basal?
Serudaptus – pseudasturid or psittacid?
Pseudasturidae (Halcyornithidae may be correct name)
Pseudasturides – formerly Pseudastur
Vastanavidae
Vastanavis (Early Eocene of Vastan, India)
Quercypsittidae
Quercypsitta (Late Eocene)

The feathers of a Yellow-headed Amazon. The blue component of the green coloration is due to light scattering while the yellow is due to pigment.

The earliest records of modern parrots date to about 23–20 mya and are also from Europe. Subsequently, the fossil record—again, mainly from Europe—consists of bones clearly recognizable as belonging to parrots of modern type. The Southern Hemisphere does not have nearly as rich a fossil record for the period of interest as the Northern, and contains no known parrot-like remains earlier than the early to middle Miocene, around 20 mya. At this point, however, is found the first unambiguous parrot fossil (as opposed to a parrot-like one), an upper jaw which is indistinguishable from that of modern cockatoos. A few modern genera are tentatively dated to a Miocene origin, but their unequivocal record stretches back only some 5 million years (see genus articles for more).

The named fossil genera of parrots are probably all in the Psittacidae or close to its ancestry:
Archaeopsittacus (Late Oligocene/Early Miocene)
Xenopsitta (Early Miocene of Czechia)
Psittacidae gen. et spp. indet. (Bathans Early/Middle Miocene of Otago, New Zealand) - several species
Bavaripsitta (Middle Miocene of Steinberg, Germany)
Psittacidae gen. et sp. indet. (Middle Miocene of France) - erroneously placed in Pararallus dispar, includes "Psittacus" lartetianus

Some Paleogene fossils are not unequivocally accepted to be of psittaciforms:
Palaeopsittacus (Early — Middle Eocene of NW Europe) - caprimulgiform (podargid?) or quercypsittid?
"Precursor" (Early Eocene) - part of this apparent chimera seems to be of a pseudasturid or psittacid
Pulchrapollia (Early Eocene) — includes "Primobucco" olsoni - psittaciform (pseudasturid or psittacid)?
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Phylogeny Parrots
Psittacidae



Cacatuidae






Strigopidae






Other birds



Phylogentic relationship between the three parrot families based on the available literature[8][14][15]


The phylogeny of the parrots is still under investigation. The classifications as presented reflects the current status, which is disputed and therefore subject to change when new studies resolve some of the open questions. For that reason, this classification should be treated as preliminary.

The Psittaciformes consist of three main lineages: Strigopidae, Psittacidae (true parrots) and Cacatuidae (cockatoos). In the past, the Strigopidae were considered part of the Psittacidae, but recent studies place this group of New Zealand species at the basis of the parrot tree next to the remaining members of the Psittacidae as well as all members of the Cacatuidae.[8][14][15]

The Cacatuidae are quite distinct, having a movable head crest, a different arrangement of the carotid arteries, a gall bladder, differences in the skull bones, and lack the Dyck texture feathers which, in the Psittacidae, scatters light in such a way as to produce the vibrant colours of so many parrots. However, the actual situation may be more complex (see below).

Lorikeets were previously regarded as a third family, Loriidae,[16] but studies using large amounts of DNA data place the group in the middle of the Psittacidae family, with as closest relatives the fig parrots (two of the three genera of the tribe Cyclopsittacini, subfamily Psittacinae) and the Budgerigar (tribe Melopsittacini, subfamily Platycercinae).[8][14][15]
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Systematics

The following classification is a version in which several subfamilies are recognized. Molecular data (see above) suggests that several subfamilies might indeed be valid and perhaps even be elevated to family rank, but the arrangement of tribes in these is not well resolved at present.

Rainbow Lorikeet
(T. h. moluccanus) perching on a garden fence in Australia

Skeleton of a parrot

Family Strigopidae: The New Zealand parrots.
Tribe Nestorini: 1 genus with only 2 living species, the Kea and Kākā of the New Zealand region.
Tribe Strigopini: The flightless, critically endangered Kakapo of New Zealand.

Family Cacatuidae: Cockatoos
Subfamily Microglossinae
Subfamily Calyptorhynchinae: dark cockatoos
Subfamily Cacatuinae: white cockatoos

Family Psittacidae: true parrots
Subfamily Arinae: Neotropical parrots, about 160 species in some 30 genera. Probably 2 distinct lineages:[14][17]
Subfamily Loriinae: Around a dozen genera with some 50 species of lorikeets and lories, centered in New Guinea, spreading to Australia, Indonesia, and the islands of the south Pacific.
Subfamily Micropsittinae: 6 species of pygmy parrot, all in a single genus.
Subfamily Psittacinae
Tribe Cyclopsittacini: fig parrots, 3 genera, all from New Guinea or nearby.
Tribe Polytelini: three genera from Australia and the Wallacea that were in the past grouped with the broad-tailed parrots.
Tribe Psittrichadini: A single species, Pesquet's Parrot.
Tribe Psittacini: Afrotropical parrots, about a dozen species in 3 genera.
Tribe Psittaculini: Paleotropic psittaculine parrots, nearly 70 living species in 12 genera, distributed from India to Australasia.
Subfamily Platycercinae: Broad-tailed parrots; nearly 30 species in roughly one dozen genera.
Tribe Melopsittacini: one genus with one species, the Budgerigar.
Tribe Neophemini: two small genera of parrots.
Tribe Pezoporini: one genus of parrots with two quite distinct species.
Tribe Platycercini: Rosellas and relatives; around 20 species in 8 genera.

Polar bear

Hi, guys! I love winter, so I decided to create something about polar bears!

The polar bear (Ursus maritimus) is a bear native largely within the Arctic circle encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the world's largest land carnivore and also the largest bear, together with the omnivorous Kodiak bear, which is approximately the same size.[3] An adult male weighs around 350–680 kg (770–1,500 lb),[4] while an adult female is about half that size. Although it is closely related to the brown bear, it has evolved to occupy a narrow ecological niche, with many body characteristics adapted for cold temperatures, for moving across snow, ice, and open water, and for hunting the seals which make up most of its diet.[5] Although most polar bears are born on land, they spend most of their time at sea (hence their scientific name meaning "maritime bear") and can hunt consistently only from sea ice, so spend much of the year on the frozen sea.

Naming and etymology

Constantine John Phipps was the first to describe the polar bear as a distinct species.[7] He chose the scientific name Ursus maritimus, the Latin for 'maritime bear',[8] due to the animal's native habitat. The Inuit refer to the animal as nanook,[9] (transliterated as nanuuq in the Inupiaq language,[10]. The Yupik also refer to the bear by nanuuk in Siberian Yupik.[citation needed]) The bear is umka in the Chukchi language. In Russian, it is usually called бе́лый медве́дь (bélyj medvédj, the white bear), though an older word still in use is ошку́й (Oshkúj, which comes from the Komi oski, "bear").[11] In French, the polar bear is referred to as ours blanc ("white bear") or ours polaire ("polar bear").[12] In the Norwegian administered Svalbard archipelago, the polar bear is referred to as Isbjørn ("ice bear").

The polar bear was previously considered to be in its own genus, Thalarctos.[13] However, evidence of hybrids between polar bears and brown bears, and of the recent evolutionary divergence of the two species, does not support the establishment of this separate genus, and the accepted scientific name is now therefore Ursus maritimus, as Phipps originally proposed.[14]
Taxonomy and evolution

Polar bears depend on sea ice as a platform for hunting seals. Large feet and short, sharp, stocky claws are adaptations to this environment.

The bear family, Ursidae, is believed to have split off from other carnivorans about 38 million years ago. The Ursinae subfamily originated approximately 4.2 million years ago. According to both fossil and DNA evidence, the polar bear diverged from the brown bear, Ursus arctos, roughly 150,000 years ago.[15] The oldest known polar bear fossil is a 130,000 to 110,000-year-old jaw bone, found on Prince Charles Foreland in 2004.[15] Fossils show that between ten to twenty thousand years ago, the polar bear's molar teeth changed significantly from those of the brown bear. Polar bears are thought to have diverged from a population of brown bears that became isolated during a period of glaciation in the Pleistocene.[16]

More recent genetic studies have shown that some clades of brown bear are more closely related to polar bears than to other brown bears,[17] meaning that the polar bear is not a true species according to some species concepts.[18] In addition, polar bears can breed with brown bears to produce fertile grizzly–polar bear hybrids,[16][19] indicating that they have only recently diverged and are genetically similar.[20] However, because neither species can survive long in the other's ecological niche, and because they have different morphology, metabolism, social and feeding behaviors, and other phenotypic characteristics, the two bears are generally classified as separate species.[20]

When the polar bear was originally documented, two subspecies were identified: Ursus maritimus maritimus by Constantine J. Phipps in 1774, and Ursus maritimus marinus by Peter Simon Pallas in 1776.[21] This distinction has since been invalidated.

One fossil subspecies has been identified. Ursus maritimus tyrannus—descended from Ursus arctos—became extinct during the Pleistocene. U.m. tyrannus was significantly larger than the living subspecies.[16]

Polar bears investigate the submarine USS Honolulu 280 miles (450 km) from the North Pole.
Population and distribution

The polar bear is found in the Arctic Circle and adjacent land masses . Due to the absence of human development in its remote habitat, it retains more of its original range than any other extant carnivore.[22] While they are rare north of 88°, there is evidence that they range all the way across the Arctic, and as far south as James Bay in Canada. They can occasionally drift widely with the sea ice, and there have been anecdotal sightings as far south as Berlevåg on the Norwegian mainland and the Kuril Islands in the Sea of Okhotsk. It is difficult to estimate a global population of polar bears as much of the range has been poorly studied, however biologists use a working estimate of about 20,000-25,000 polar bears worldwide.[1][23]

There are 19 generally recognized discrete subpopulations.[23][24] The subpopulations display seasonal fidelity to particular areas, but DNA studies show that they are not reproductively isolated.[25] The thirteen North American subpopulations range from the Beaufort Sea south to Hudson Bay and east to Baffin Bay in western Greenland and account for about 70% of the global population. The Eurasian population is broken up into the eastern Greenland, Barents Sea, Kara Sea, Laptev Sea, and Chukchi Sea subpopulations, though there is considerable uncertainty about the structure of these populations due to limited mark and recapture data.


Polar bears play-fighting

The range includes the territory of five nations: Denmark (Greenland), Norway(Svalbard), Russia, US (Alaska) and Canada. These five nations are the signatories of the 1973 International Agreement for the Conservation of Polar Bears, which mandates cooperation on research and conservations efforts throughout the polar bear's range.

Modern methods of tracking polar bear populations have been implemented only since the mid-1980s, and are expensive to perform consistently over a large area.[26] The most accurate counts require flying a helicopter in the Arctic climate to find polar bears, shooting a tranquilizer dart at the bear to sedate it, and then tagging the bear.[26] In Nunavut, some Inuit have reported increases in bear sightings around human settlements in recent years, leading to a belief that populations are increasing. Scientists have responded by noting that hungry bears may be congregating around human settlements, leading to the illusion that populations are higher than they actually are.[26] The Polar Bear Specialist Group of the IUCN takes the position that "estimates of subpopulation size or sustainable harvest levels should not be made solely on the basis of traditional ecological knowledge without supporting scientific studies."[27]

Of the 19 recognized polar bear subpopulations, 8 are declining, 3 are stable, 1 is increasing, and 7 have insufficient data.[6][23]
Habitat


A cub nursing

The polar bear is often regarded as a marine mammal because it spends many months of the year at sea.[28] Its preferred habitat is the annual sea ice covering the waters over the continental shelf and the Arctic inter-island archipelagos. These areas, known as the "Arctic ring of life", have high biological productivity in comparison to the deep waters of the high Arctic.[22][29] The polar bear tends to frequent areas where sea ice meets water, such as polynyas and leads (temporary stretches of open water in Arctic ice), to hunt the seals that make up most of its diet.[30] Polar bears are therefore found primarily along the perimeter of the polar ice pack, rather than in the Polar Basin close to the North Pole where the density of seals is low.[31]

A polar bear.

Annual ice contains areas of water that appear and disappear throughout the year as the weather changes. Seals migrate in response to these changes, and polar bears must follow their prey.[29] In Hudson Bay, James Bay, and some other areas, the ice melts completely each summer (an event often referred to as "ice-floe breakup"), forcing polar bears to go onto land and wait through the months until the next freeze-up.[29] In the Chukchi and Beaufort seas, polar bears retreat each summer to the ice further north that remains frozen year-round.
Biology and behavior
Physical characteristics

Polar bear skeleton

The polar bear is the largest terrestrial carnivore, being more than twice as big as the Siberian Tiger.[32] It shares the title of largest land predator (and largest bear species) with the Kodiak bear.[33] Adult males weigh 350–680 kg (770-1500 lbs) and measure 2.4–3 m (7.9–9.8 ft) in length.[34] Adult females are roughly half the size of males and normally weigh 150–249 kg (330–550 lb), measuring 1.8–2.4 metres (5.9–7.9 ft) in length. When pregnant, however, they can weigh as much as 499 kg (1,100 lb).[34] The polar bear is among the most sexually dimorphic of mammals, surpassed only by the pinnipeds.[35] The largest polar bear on record, reportedly weighing 1,002 kg (2,210 lb), was a male shot at Kotzebue Sound in northwestern Alaska in 1960.[36]

Polar bears have evolved unique features for Arctic life, including furred feet that have good traction on ice.

Compared with its closest relative, the brown bear, the polar bear has a more elongated body build and a longer skull and nose.[20] As predicted by Allen's rule for a northerly animal, the legs are stocky and the ears and tail are small.[20] However, the feet are very large to distribute load when walking on snow or thin ice and to provide propulsion when swimming; they may measure 30 cm (12 in) across in an adult.[37] The pads of the paws are covered with small, soft papillae (dermal bumps) which provide traction on the ice.[20] The polar bear's claws are short and stocky compared to those of the brown bear, perhaps to serve the former's need to grip heavy prey and ice.[20] The claws are deeply scooped on the underside to assist in digging in the ice of the natural habitat. Despite a recurring Internet meme that all polar bears are left-handed,[38][39] there is no scientific evidence to support this claim.[40] Unlike the brown bear, Polar Bears in captivity are rarely overweight or particularly large, possibly as a reaction to the warm temperatures of most zoos.

The 42 teeth of a polar bear reflect its highly carnivorous diet.[20] The cheek teeth are smaller and more jagged than in the brown bear, and the canines are larger and sharper.[20] The dental formula is:[20]Dentition
3.1.4.2
3.1.4.3


Polar bears are superbly insulated by up to 10 cm (3.9 in) of blubber,[37] their hide and their fur; they overheat at temperatures above 10 °C (50 °F), and are nearly invisible under infrared photography.[41] Polar bear fur consists of a layer of dense underfur and an outer layer of guard hairs, which appear white to tan but are actually transparent.[37] The guard hair is 5–15 cm (2.0–5.9 in) over most of the body.[42] Polar bears gradually moult from May to August,[43] but, unlike other Arctic mammals, they do not shed their coat for a darker shade to camouflage themselves in the summer conditions. The hollow guard hairs of a polar bear coat were once thought to act as fiber-optic tubes to conduct light to its black skin, where it could be absorbed; however, this theory was disproved by recent studies.[44]

Polar bear diving in a zoo

A polar bear in a synthetic arctic zoo environment.

The white coat usually yellows with age. When kept in captivity in warm, humid conditions, the fur may turn a pale shade of green due to algae growing inside the guard hairs.[45] Males have significantly longer hairs on their forelegs, that increase in length until the bear reaches 14 years of age. The male's ornamental foreleg hair is thought to attract females, serving a similar function to the lion's mane.[46]

The polar bear has an extremely well-developed sense of smell, being able to detect seals nearly 1 mi (1.6 km) away and buried under 3 ft (0.91 m) of snow.[47] Its hearing is about as acute as that of a human, and its vision is also good at long distances.[47]

The polar bear is an excellent swimmer and individuals have been seen in open Arctic waters as far as 200 mi (320 km) from land. With its body fat providing buoyancy, it swims in a dog-paddle fashion using its large forepaws for propulsion.[48] Polar bears can swim 6 miles/hour. When walking, the polar bear tends to have a lumbering gait and maintains an average speed of around 5.5 km/h (3.5 m.p.h.).[48]
Hunting and diet

The long muzzle and neck of the polar bear help it to search in deep holes for seals, while powerful hindquarters enable it to drag massive prey.[49]

The polar bear is the most carnivorous member of the bear family, and most of its diet consists of ringed and bearded seals.[50] The Arctic is home to millions of seals, which become prey when they surface in holes in the ice in order to breathe, or when they haul out on the ice to rest.[49] Polar bears hunt primarily at the interface between ice, water, and air; they only rarely catch seals on land or in open water.[51]

The polar bear's most common hunting method is called still-hunting:[52] The bear uses its excellent sense of smell to locate a seal breathing hole, and crouches nearby in silence for a seal to appear.[49] When the seal exhales, the bear smells its breath, reaches into the hole with a forepaw, and drags it out onto the ice.[49] The polar bear kills the seal by biting its head to crush its skull.[49] The polar bear also hunts by stalking seals resting on the ice: Upon spotting a seal, it walks to within 100 yd (91 m), and then crouches. If the seal does not notice, the bear creeps to within 30 to 40 feet (9.1 to 12 m) of the seal and then suddenly rushes forth to attack.[49] A third hunting method is to raid the birth lairs that female seals create in the snow.[52]

Polar bear at a whale carcass

A widespread legend tells that polar bears cover their black noses with their paws when hunting. This behavior, if it happens, is rare — although the story exists in native oral history and in accounts by early Arctic explorers, there is no record of an eyewitness account of the behavior in recent decades.[48]

Mature bears tend to eat only the calorie-rich skin and blubber of the seal, whereas younger bears consume the protein-rich red meat.[49] For subadult bears which are independent of their mother but have not yet gained enough experience and body size to successfully hunt seals, scavenging the carcasses from other bears' kills is an important source of nutrition. Subadults may also be forced to accept a half-eaten carcass if they kill a seal but cannot defend it from larger polar bears. After feeding, polar bears wash themselves with water or snow.[48]

The polar bear is an enormously powerful predator. It can kill an adult walrus, although it rarely attempts to as a walrus can be more than twice the bear's weight.[53] Polar bears also have preyed on beluga whales, by swiping at them at breathing holes. The whales are of similar size to the walrus and nearly as difficult for the bear to subdue. Most terrestrial animals in the Arctic can outrun the polar bear on land as polar bears overheat quickly, and most marine animals the bear encounters can outswim it. In some areas, the polar bear's diet is supplemented by walrus calves and by the carcasses of dead adult walruses or whales, whose blubber is readily devoured even when rotten.[54]

With the exception of pregnant females, polar bears are active year-round,[55] although they have a vestigial hibernation induction trigger in their blood. Unlike brown and black bears, polar bears are capable of fasting for up to several months during late summer and early fall, when they cannot hunt for seals because the sea is unfrozen.[55] When sea ice is unavailable during summer and early autumn, some populations live off fat reserves for months at a time.[41] Polar bears have also been observed to eat a wide variety of other wild foods, including muskox, reindeer, birds, eggs, rodents, shellfish, crabs, and other polar bears. They may also eat plants, including berries, roots, and kelp, however none of these are a significant part of their diet.[53] The polar bear's biology is specialized to require large amounts of fat from marine mammals, and it cannot derive sufficient caloric intake from terrestrial food.[56][57]

Being both curious animals and scavengers,[53][58] polar bears investigate and consume garbage where they come into contact with humans.[53] Polar bears may attempt to consume almost anything they can find, including hazardous substances such as styrofoam, plastic, car batteries, ethylene glycol, hydraulic fluid, and motor oil.[53][58] The dump in Churchill, Manitoba was closed in 2006 to protect bears, and waste is now recycled or transported to Thompson, Manitoba.[59][60]

Polar bear males frequently play-fight. During the mating season, actual fighting is intense and often leaves scars or broken teeth.
Behavior

Unlike grizzly bears, polar bears are not territorial. Although stereotyped as being voraciously aggressive, they are normally cautious in confrontations, and often choose to escape rather than fight.[61] Fat polar bears rarely attack humans unless severely provoked, whereas hungry polar bears are extremely unpredictable and are known to kill and sometimes eat humans.[54] Polar bears are stealth hunters, and the victim is often unaware of the bear's presence until the attack is underway.[62] Whereas brown bears often maul a person and then leave, polar bear attacks are more likely to be predatory and are almost always fatal.[62] However, due to the very small human population around the Arctic, such attacks are rare.

In general, adult polar bears live solitary lives. Yet, they have often been seen playing together for hours at a time and even sleeping in an embrace,[54] and polar bear zoologist Nikita Ovsianikov has described adult males as having "well-developed friendships."[61] Cubs are especially playful as well. Among young males in particular, play-fighting may be a means of practicing for serious competition during mating seasons later in life.[63] Polar bears have a wide range of vocalisations, including bellows, roars, growls, chuffs and purrs.[64]

In 1992, a photographer near Churchill took a now widely circulated set of photographs of a polar bear playing with a Canadian Eskimo Dog a tenth of its size.[65][66] The pair wrestled harmlessly together each afternoon for ten days in a row for no apparent reason, although the bear may have been trying to demonstrate its friendliness in the hope of sharing the kennel's food.[65] This kind of social interaction is uncommon; it is far more typical for polar bears to behave aggressively towards dogs.[65]
Reproduction and lifecycle

A polar bear swimming

Courtship and mating take place on the sea ice in April and May, when polar bears congregate in the best seal hunting areas.[67] A male may follow the tracks of a breeding female for 100 km (62 mi) or more, and after finding her engage in intense fighting with other males over mating rights, fights which often result in scars and broken teeth.[67] Polar bears have a generally polygynous mating system; recent genetic testing of mothers and cubs, however, has uncovered cases of litters in which cubs have different fathers.[68] Partners stay together and mate repeatedly for an entire week; the mating ritual induces ovulation in the female.[69]

After mating, the fertilized egg remains in a suspended state until August or September. During these four months, the pregnant female eats prodigious amounts of food, gaining at least 200 kg (440 lb) and often more than doubling her body weight.[67]
Maternity denning and early life

Cubs are born helpless, and typically nurse for two and a half years.

When the ice floes break up in the fall, ending the possibility of hunting, each pregnant female digs a maternity den consisting of a narrow entrance tunnel leading to one to three chambers.[67] Most maternity dens are in snowdrifts, but may also be made underground in permafrost if it is not sufficiently cold yet for snow.[67] In most subpopulations, maternity dens are situated on land a few kilometers from the coast, and the individuals in a subpopulation tend to reuse the same denning areas each year.[22] The polar bears that do not den on land make their dens on the sea ice. In the den, she enters a dormant state similar to hibernation. This hibernation-like state does not consist of continuous sleeping; however, the bear's heart rate slows from 46 to 27 beats per minute.[70] Her body temperature does not decrease during this period as it would for a typical mammal in hibernation.[41][71]

Between November and February, cubs are born blind, covered with a light down fur, and weighing less than 0.9 kg (2.0 lb).[69] On average, each litter has two cubs.[67] The family remains in the den until mid-February to mid-April, with the mother maintaining her fast while nursing her cubs on a fat-rich milk.[67] By the time the mother breaks open the entrance to the den, her cubs weigh about 10 to 15 kilograms (22 to 33 lb).[67] For about 12 to 15 days, the family spends time outside the den while remaining in its vicinity, the mother grazing on vegetation while the cubs become used to walking and playing.[67] Then they begin the long walk from the denning area to the sea ice, where the mother can once again catch seals.[67] Depending on the timing of ice-floe breakup in the fall, she may have fasted for up to eight months.[67]

Cubs may fall prey to wolves or to starvation. Female polar bears are noted for both their affection towards their offspring, and their valiance in protecting them. One case of adoption of a wild cub has been confirmed by genetic testing.[68] Adult male bears males occasionally kill and eat polar bear cubs,[72] for reasons that are unclear.[73] In Alaska, 42% of cubs now reach 12 months of age, down from 65% 15 years ago.[74] In most areas, cubs are weaned at two and a half years of age,[67] when the mother chases them away or abandons them. The western coast of Hudson Bay is unusual in that its female polar bears sometimes wean their cubs at only one and a half years.[67] This was the case for 40% of cubs there in the early 1980s; however by the 1990s, fewer than 20% of cubs were weaned this young.[75] After the mother leaves, sibling cubs sometimes travel and share food together for weeks or months.[54]

A female emerging from her maternity den
Later life

Females begin to breed at the age of four years in most areas, and five years in the Beaufort Sea area.[67] Males usually reach sexual maturity at six years, however as competition for females is fierce, many do not breed until the age of eight or ten.[67] A study in Hudson Bay indicated that both the reproductive success and the maternal weight of females peaked in their mid-teens.[76]

Polar bears appear to be less affected by infectious diseases and parasites than most terrestrial mammals.[73] Polar bears are especially susceptible to Trichinella, a parasitic roundworm they contract through cannibalism,[77] although infections are usually not fatal.[73] Only one case of a polar bear with rabies has been documented, even though polar bears frequently interact with Arctic foxes, which often carry rabies.[73] Bacterial Leptospirosis and Morbillivirus have been recorded. Polar bears sometimes have problems with various skin diseases which may be caused by mites or other parasites.

Polar bears rarely live beyond 25 years.[78] The oldest wild bears on record died at the age of 32, whereas the oldest captive was a female who died in 1991 at the age of 43.[79] The oldest living polar bear is Debby of the Assiniboine Park Zoo, who was probably born in December, 1966.[79] The causes of death in wild adult polar bears are poorly understood, as carcasses are rarely found in the species's frigid habitat.[73] In the wild, old polar bears eventually become too weak to catch food, and gradually starve to death. Polar bears injured in fights or accidents may either die from their injuries or become unable to hunt effectively, leading to starvation.[73]
Ecological role

A female nursing a two-year-old cub

The polar bear is the apex predator within its range. Several animal species, particularly Arctic Foxes and Glaucous Gulls, routinely scavenge polar bear kills.[48]

The relationship between ringed seals and polar bears is so close that the abundance of ringed seals in some areas appears to regulate the density of polar bears, while polar bear predation in turn, regulates density and reproductive success of ringed seals.[51] The evolutionary pressure of polar bear predation on seals probably accounts for some significant differences between Arctic and Antarctic seals. Compared to the Antarctic, where there is no major surface predator, Arctic seals use more breathing holes per individual, appear more restless when hauled out on the ice, and rarely defecate on the ice.[48] The baby fur of most Arctic seal species is white, presumably to provide camouflage from predators, whereas Antarctic seals all have dark fur at birth.[48]

Polar bears rarely enter conflict with other predators, though recent brown bear encroachments into polar bear territories have led to antagonistic encounters. Brown bears tend to dominate polar bears in disputes over carcasses,[80] and dead polar bear cubs have been found in brown bear dens.[81] Wolves are rarely encountered by polar bears, though there are two records of wolf packs killing polar bear cubs.[82] Polar bears are sometimes the host of arctic mites such as Alaskozetes antarcticus.[48]
Hunting
Indigenous people

Skins of hunted polar bears in Ittoqqortoormiit, Greenland

Polar bears have long provided important raw materials for Arctic peoples, including the Inuit, Yupik, Chukchi, Nenets, Russian Pomors and others. Hunters commonly used teams of dogs to distract the bear, allowing the hunter to spear the bear or shoot it with arrows at closer range.[83] Almost all parts of captured animals had a use.[84] The fur was used in particular to sew trousers and, by the Nenets, to make galoshes-like outer footwear called tobok; the meat is edible, despite some risk of trichinosis; the fat was used in food and as a fuel for lighting homes, alongside seal and whale blubber; sinews were used as thread for sewing clothes; the gallbladder and sometimes heart were dried and powdered for medicinal purposes; the large canine teeth were highly valued as talismans.[85] Only the liver was not used, as its high concentration of vitamin A is poisonous.[86] Hunters make sure to either toss the liver into the sea or bury it in order to spare their dogs from potential poisoning.[85] Traditional subsistence hunting was on a small enough scale to not significantly affect polar bear populations, mostly because of the sparseness of the human population in polar bear habitat

The polar bear is classified as a vulnerable species, with 8 of the 19 polar bear subpopulations in decline.[6] For decades, unrestricted hunting[clarification needed] raised international concern for the future of the species; populations have rebounded after controls and quotas began to take effect.[citation needed] For thousands of years, the polar bear has been a key figure in the material, spiritual, and cultural life of Arctic indigenous peoples, and the hunting of polar bears remains important in their cultures.

The IUCN now lists global warming as the most significant threat to the polar bear, primarily because the melting of its sea ice habitat reduces its ability to find sufficient food. The IUCN states, "If climatic trends continue polar bears may become extirpated from most of their range within 100 years."[7] On 14 May 2008, the United States Department of the Interior listed the polar bear as a threatened species under the Endangered Species Act.

Owl

The Owls are the order Strigiformes, comprising 200 extant bird of prey species. Most are solitary, and nocturnal, with some exceptions (e.g. the Northern Hawk Owl). Owls hunt mostly small mammals, insects, and other birds, though a few species specialize in hunting fish. They are found in all regions of the Earth except Antarctica, most of Greenland, and some remote islands. Though owls are typically solitary, the literary collective noun for a group of owls is a parliament.

Living owls are divided into two families: the typical owls, Strigidae; and the barn-owls, Tytonidae.

Description

A little owl with its head completely facing the back.

Owls have large forward-facing eyes and ear-holes, a hawk-like beak, a flat face, and usually a conspicuous circle of feathers, a facial disc, around each eye. Although owls have binocular vision, their large eyes are fixed in their sockets, as with other birds, and they must turn their entire head to change views. Most birds of prey sport eyes on the sides of their heads, but the stereoscopic nature of the owl's forward-facing eyes permits a greater sense of depth perception necessary for low-light hunting.

Owls are farsighted and are unable to see anything clearly within a few centimeters of their eyes. Caught prey can be felt by owls with the use of filoplumes, which are small hair-like feathers on the beak and feet that act as "feelers". Their far vision, particularly in low light, is exceptionally good. Contrary to popular myth, an owl cannot turn its head completely backwards. It can turn its head 135 degrees in either direction; it can thus look behind its own shoulders, with a total 270-degree field of view.[1]

The smallest owl is the Elf Owl (Micrathene whitneyi), at as little as 31 g (1.1 oz) and 13.5cm (5.3 inches). Some of the pygmy owls are scarcely larger. The largest owls are two of the eagle owls; the Eurasian Eagle Owl (Bubo bubo) and Blakiston's Fish Owl (Bubo blakistoni)—which may reach a size of 60 - 71cm (28.4 in) long, have a wingspan of almost 2 m (6.6 ft), and an average weight of nearly 4.5kg (10 lb).

Eagle Owl

Different species of owls make different sounds; the wide range of calls aids owls in finding mates or announcing their presence to potential competitors, and also aids ornithologists and birders in locating these birds and recognizing species. The facial disc helps to funnel the sound of prey to their ears. In many species, these are placed asymmetrically, for better directional location.[2][verification needed]

The plumage of owls is generally cryptic, but many species have facial and head markings, including face masks, ear tufts and brightly coloured irises. These markings are generally more common in species inhabiting open habitats, and are thought to be used in signalling with other owls in low light conditions.[3]

Owl eggs are usually white and almost spherical, and range in number from a few to a dozen, depending on species. Eggs are laid at intervals of 1 to 3 days and do not hatch at the same time. This accounts for the wide variation in the size of sibling nestlings. Owls do not construct nests, but rather look for a sheltered nesting site or an abandoned nest in trees, underground burrows, or in buildings, barns and caves.
Behaviour

Most owls are nocturnal, actively hunting for prey only under the cover of darkness. Several types of owl, however, are crepuscular, active during the twilight hours of dawn and dusk; one example is the pygmy owl (Glaucidium). A few owls are also active during the day; examples are the Burrowing Owl (Speotyto cunicularia) and the Short-eared Owl (Asio flammeus).

The serrations on the leading edge of an owl's flight feathers reduce noise.

Much of the owls' hunting strategy depends on stealth and surprise. Owls have at least two adaptations that aid them in achieving stealth. First, the dull coloration of owls' feathers can render them almost invisible under certain conditions. Secondly, serrated edges on the leading edge owls' remiges muffle an owl's wingbeats, allowing its flight to be practically silent. Some fish-eating owls, for which silence is of no evolutionary advantage, lack this adaptation.

An owl's sharp beak and powerful talons allow it to kill its prey before swallowing it whole (unless it is too big). Scientists studying the diets of owls are helped by their habit of regurgitating the indigestible parts of their prey (such as bones, scales and fur) in the form of pellets. These "owl pellets", which are plentiful and easy to interpret, are often sold by companies to schools for dissection by students as a lesson in biology and ecology. [4]
Evolution and systematics

A Great Horned Owl (Bubo virginianus) sleeping at daytime in a hollow tree.

The systematic placement of owls is disputed. For example, the Sibley-Ahlquist taxonomy finds that, based on DNA-DNA hybridization, owls are more closely related to the nightjars and their allies (Caprimulgiformes) than to the diurnal predators in the order Falconiformes; consequently, the Caprimulgiformes are placed in the Strigiformes, and the owls in general become a family Strigidae. This is not supported by more recent research.[5] In any case, the relationships of the Caprimulgiformes, the owls, the falcons and the accipitrid raptors are not resolved to satisfaction; currently there is an increasing trend to consider each group (with the possible exception of the accipitrids) a distinct order.

There are some 220 to 225 extant species of owls, subdivided into two families: typical owls (Strigidae) and barn-owls (Tytonidae). Some entirely extinct families have also been erected based on fossil remains; these differ much from modern owls in being less specialized or specialized in a very different way (such as the terrestrial Sophiornithidae). The Paleocene genera Berruornis and Ogygoptynx show that owls were already present as a distinct lineage some 60 - 57 mya (million years ago), and presumably also some 5 million years earlier, at the extinction of the non-avian dinosaurs. This makes them one of the oldest known groups of non-Galloanserae landbirds. The supposed "Cretaceous owls" Bradycneme and Heptasteornis are apparently non-avialan maniraptors.[6]

During the Paleogene, the Strigiformes radiated into ecological niches now mostly filled by other groups of birds. The owls as we know them today, on the other hand, evolved their characteristic morphology and adaptations during that time, too. By the early Neogene, the other lineages had been displaced by other bird orders, leaving only barn-owls and typical owls. The latter at that time were usually a fairly generic type of (probably earless) owl similar to today's North American Spotted Owl or the European Tawny Owl; the diversity in size and ecology found in typical owls today developed only subsequently.

Around the Paleogene-Neogene boundary (some 25 mya), barn-owls were the dominant group of owls in southern Europe and adjacent Asia at least; the distribution of fossil and present-day owl lineages indicates that their decline is contemporary with the evolution of the different major lineages of typical owls, which for the most part seems to have taken place in Eurasia. In the Americas, there was rather an expansion of immigrant lineages of ancestral typical owls.

The supposed fossil herons "Ardea" perplexa (Middle Miocene of Sansan, France) and "Ardea" lignitum (Late Pliocene of Germany) were more probably owls; the latter was apparently close to the modern genus Bubo. Judging from this, the Late Miocene remains from France described as "Ardea" aureliensis should also be restudied.[7] The Messelasturidae, some of which were initially believed to be basal Strigiformes, are now generally accepted to be diurnal birds of prey showing some convergent evolution towards owls. The taxa often united under Strigogyps[8] were formerly placed in part with the owls, specifically the Sophiornithidae; they appear to be Ameghinornithidae instead.[9]

For fossil species and paleosubspecies of extant taxa, see the genus and species articles.

Unresolved and basal forms (all fossil)
Berruornis (Late Paleocene of France) - basal? Sophornithidae?
Strigiformes gen. et ap. indet. (Late Paleocene of Zhylga, Kazakhstan)
Palaeoglaux (Middle – Late Eocene of WC Europe) - own family Palaeoglaucidae or Strigidae?
Palaeobyas (Late Eocene/Early Oligocene of Quercy, France) - Tytonidae? Sophiornithidae?
Palaeotyto (Late Eocene/Early Oligocene of Quercy, France) - Tytonidae? Sophiornithidae?
Strigiformes gen. et spp. indet. (Early Oligocene of Wyoming, USA)[10]
Ogygoptyngidae
Ogygoptynx (Middle/Late Paleocene of Colorado, USA)
Protostrigidae
Eostrix (Early Eocene of WC USA and England - Middle Eocene of WC USA)
Minerva (Middle – Late Eocene of W USA) - formerly Protostrix, includes "Aquila" ferox, "Aquila" lydekkeri, and "Bubo" leptosteus
Oligostrix (mid-Oligocene of Saxony, Germany)
Sophiornithidae
Sophiornis
Strigidae: Typical owls

A Long-eared Owl, Asio otus, in erect pose
Aegolius: saw-whet owls, four species
Asio: eared owls, 6–7 species
Athene: 2–4 species (depending on whether Speotyto and Heteroglaux are included or not)
Bubo: horned owls, eagle-owls and fish-owls; paraphyletic with Nyctea, Ketupa and Scotopelia, some 25 species
Ciccaba: four species
Glaucidium: pygmy-owls, about 30–35 species
Gymnoglaux: Bare-legged Owl or Cuban Screech-owl
Jubula: Maned Owl
Lophostrix: Crested Owl
Megascops: screech-owls, some 20 species
Micrathene: Elf Owl
Mimizuku: Giant Scops-owl or Mindanao Eagle-owl
Ninox: Australasian hawk-owls, some 20 species
Nesasio - Fearful Owl
Otus: scops-owls; probably paraphyletic, about 45 species
Pseudoscops: Jamaican Owl and possibly Striped Owl
Ptilopsis: white-faced owls, two species
Pulsatrix: spectacled owls, three species
Pyrroglaux: Palau Owl
Strix: earless owls, about 15 species
Surnia: Northern Hawk-owl
Uroglaux: Papuan Hawk-owl
Xenoglaux: Long-whiskered Owlet
Mascarenotus: Mascarene owls, three species; extinct (c.1850)
Sceloglaux: Laughing Owl; extinct (1914?)
Grallistrix: stilt-owls, four species; prehistoric
Ornimegalonyx: Caribbean giant owls, 1–2 species; prehistoric

Fossil genera
Mioglaux (Late Oligocene? - Early Miocene of WC Europe) - includes "Bubo" poirreiri
"Otus/Strix" wintershofensis: fossil (Early/Middle Miocene of Wintershof West, Germany) - may be close to extant genus Ninox[10]
Intutula (Early/Middle –? Late Miocene of C Europe) - includes "Strix/Ninox" brevis
Alasio (Middle Miocene of Vieux-Collonges, France) - includes "Strix" collongensis

Placement unresolved

Masked Owl, Tyto novaehollandiae.
"Strix" edwardsi: fossil (Middle Miocene)
"Asio" pygmaeus: fossil (Early Pliocene of Odessa, Ukraine)
Ibiza Owl, Strigidae gen. et sp. indet.: prehistoric[11]
Tytonidae: Barn-owls
Genus Tyto: typical barn-owls, stand up to 1⁄2 feet (0.15 m) tall. Some 15 species and possibly one recently extinct
Genus Phodilus: bay-owls, 1–2 extant species and possibly one recently extinct

Fossil genera
Nocturnavis (Late Eocene/Early Oligocene) - includes "Bubo" incertus
Necrobyas (Late Eocene/Early Oligocene - Late Miocene) - includes "Bubo" arvernensis and Paratyto
Selenornis (Late Eocene/Early Oligocene) - includes "Asio" henrici
Prosybris (Early Oligocene? - Early Miocene)

Rare animals. Axolot salamander

Hi, guys! Nowdays, when I'm posting this I haven't got any message for you. 

he axolotl (pronounced /ˈæksəlɒtəl/), Ambystoma mexicanum, is the best known of the Mexican neotenic mole salamanders belonging to the Tiger Salamander complex. Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled. The species originates from the lake underlying Mexico City and is also called ajolote (which is also the common name for the Mexican Mole Lizard). Axolotls are used extensively in scientific research due to their ability to regenerate most body parts, ease of breeding, and large embryos. They are commonly kept as pets in the United States, Great Britain, Australia, Japan (sold under the name wooper looper (ウーパールーパー Ūpā Rūpā?)) and other countries.

Axolotls should not be confused with waterdogs, the larval stage of the closely related Tiger Salamanders (Ambystoma tigrinum and Ambystoma mavortium), which are widespread in much of North America and also occasionally become neotenic, nor with mudpuppies (Necturus spp.), fully-aquatic salamanders which are not closely related to the axolotl but bear a superficial resemblance.

As of 2008, wild axolotls are near extinction  due to urbanization in Mexico City and polluted waters. Nonnative fish such as African tilapia and Asian carp have also recently been introduced to the waters. These new fish have been eating the axolotls' young, as well as its primary source of food.[2] The axolotl is currently on the International Union for Conservation of Nature's annual Red List of threatened species.

Description

Adult axolotl.

A sexually mature adult axolotl, at age 18–24 months, ranges in length from 15–45 centimetres (5.9–18 in), although a size close to 23 centimetres (9.1 in) is most common and greater than 30 centimetres (12 in) is rare. Axolotls possess features typical of salamander larvae, including external gills and a caudal fin extending from behind the head to the vent. Their heads are wide, and their eyes are lidless. Their limbs are underdeveloped and possess long, thin digits. Males are identified by their swollen cloacae lined with papillae, while females are noticeable for their wider bodies full of eggs. Three pairs of external gill stalks (rami) originate behind their heads and are used to move oxygenated water. The external gill rami are lined with filaments (fimbriae) to increase surface area for gas exchange. Four gill slits lined with gill rakers are hidden underneath the external gills. Axolotls have barely visible vestigial teeth, which would have developed during metamorphosis. The primary method of feeding is by suction, during which their rakers interlock to close the gill slits. External gills are used for respiration, although buccal pumping (gulping air from the surface) may also be used in order to provide oxygen to their lungs. Axolotls have four different colours, two naturally occurring colours and two mutants. The two naturally occurring colours are wildtype (varying shades of brown usually with spots) and melanoid (black). The two mutant colours are leucistic (pale pink with black eyes) and albino (golden, tan or pale pink with pink eyes).
Habitat and ecology

The axolotl is only native to Lake Xochimilco and Lake Chalco in central Mexico. Unfortunately for the axolotl, Lake Chalco no longer exists as it was drained by humans to avoid periodic flooding, and Lake Xochimilco remains a diminished glimpse of its former self, existing mainly as canals. The water temperature in Xochimilco rarely rises above 20 °C (68 °F), though it may fall to 6 or 7 °C (45 °F) in the winter, and perhaps lower. The wild population has been put under heavy pressure by the growth of Mexico City.  Axolotls are also sold as food in Mexican markets and were a staple in the Aztec diet  They are currently listed by CITES as an endangered species and by IUCN as critically endangered in the wild, with a decreasing population.

Axolotls are members of the Ambystoma tigrinum (Tiger salamander) complex, along with all other Mexican species of Ambystoma. Their habitat is like that of most neotenic species—a high altitude body of water surrounded by a risky terrestrial environment. These conditions are thought to favor neoteny. However, a terrestrial population of Mexican Tiger Salamanders occupies and breeds in the axolotl's habitat.

The axolotl is carnivorous, consuming small prey such as worms, insects, and small fish in the wild. Axolotls locate food by smell, and will "snap" at any potential meal, sucking the food into their stomachs with vacuum force.
Axolotl's neoteny

Axolotls exhibit a property called neoteny, meaning that they reach sexual maturity without undergoing metamorphosis. Many species within the axolotl's genus are either entirely neotenic or have neotenic populations. In the axolotl, metamorphic failure is caused by a lack of thyroid stimulating hormone, which is used to induce the thyroid to produce thyroxine in transforming salamanders. The genes responsible for neoteny in laboratory animals may have been identified; however, they are not linked in wild populations, suggesting artificial selection is the cause of complete neoteny in laboratory and pet axolotls.

Unlike some other neotenic salamanders (Sirens and Necturus), axolotls can be induced to metamorphose by an injection of iodine (used in the production of thyroid hormones) or by shots of thyroxine hormone. Another method for inducing transformation, though one that is very rarely successful, involves removing an axolotl in good condition to a shallow tank in a vivarium and slowly reducing the water level so that the axolotl has difficulty submerging. It will then, over a period of weeks, slowly metamorphose into an adult salamander. During transformation, the air in the vivarium must remain moist, and the maturing axolotl sprayed with a fine mist of pure water. The odds of the animal being able to metamorphose via this method are extremely small, and most attempts at inducing metamorphosis lead to death. This is likely due to the strong genetic basis for neoteny in laboratory and pet axolotls, which means that few captive animals have the ability to metamorphose on their own. Artificial metamorphosis also dramatically shortens the axolotl's lifespan if it survives the process. A neotenic axolotl will live an average of 10–15 years (though an individual in Paris is credited with achieving 25 years), while a metamorphosed specimen will scarcely live past the age of five. The adult form resembles a terrestrial Mexican Tiger Salamander, but has several differences, such as longer toes, which support its status as a separate species.
Use as a model organism

Six adult axolotls (including a leucistic specimen) were shipped from Mexico City to the Jardin des Plantes in Paris in 1863. Unaware of their neoteny, Auguste Duméril was surprised when, instead of the axolotl, he found in the vivarium a new species, similar to the salamander. This discovery was the starting point of research about neoteny. It is not certain that Mexican Tiger Salamanders were not included in the original shipment.

Vilem Laufberger of Germany used thyroid hormone injections to induce an axolotl to grow into a terrestrial adult salamander. The experiment was repeated by the Englishman Julian Huxley, who was unaware the experiment had already been done, using ground thyroid hormones. Since then, experiments have been done often with injections of iodine or various thyroid hormones used to induce metamorphosis.

Today, the axolotl is still used in research as a model organism, and large numbers are bred in captivity. Axolotls are especially easy to breed compared to other salamanders in their family, which are almost never captive bred due to the demands of terrestrial life. One attractive feature for research is the large and easily manipulated embryo, which allows viewing of the full development of a vertebrate. Axolotls are used in heart defect studies due to the presence of a mutant gene that causes heart failure in embryos. Since the embryos survive almost to hatching with no heart function, the defect is very observable. The presence of several color morphs has also been extensively studied.

The feature of the salamander that attracts most attention is its healing ability: the axolotl does not heal by scarring and is capable of the regeneration of entire lost appendages in a period of months, and, in certain cases, more vital structures. Some have indeed been found restoring the less vital parts of their brains. They can also readily accept transplants from other individuals, including eyes and parts of the brain—restoring these alien organs to full functionality. In some cases, axolotls have been known to repair a damaged limb as well as regenerating an additional one, ending up with an extra appendage that makes them attractive to pet owners as a novelty. In metamorphosed individuals, however, the ability to regenerate is greatly diminished. The axolotl is therefore used as a model for the development of limbs in vertebrates.
Captivity

An axolotl in captivity

Axolotls live at temperatures of 14 °C (57 °F)-20 °C (68 °F), preferably 17 °C (63 °F)-18 °C (64 °F). As for all cold-blooded organisms, lower temperatures result in slower metabolism; higher temperatures can lead to stress and increased appetite. Chlorine, commonly added to tapwater, is harmful to axolotls. A single typical axolotl typically requires a 40 litres (8.8 imp gal; 11 US gal) tank with a water depth of at least 15 centimetres (5.9 in). Axolotls spend a majority of the time at the bottom of the tank.

In laboratory colonies, adult axolotls are often housed three to a one-gallon container, and water changes are performed more regularly. Salts, such as Holtfreter's solution, are usually added to the water to prevent infection.

In captivity, axolotls eat a variety of readily available foods, including trout and salmon pellets, frozen or live bloodworms, earthworms, and waxworms.

Facts about pets.Hamsters

Hi, guys! Now, when I am creating this post, I have so cool mind, so, I decided to tell about one of my favourite pets, the funniest animal in the world- hamster! ;)

Hamsters are rodents belonging to the subfamily Cricetinae. The subfamily contains about 25 species, classified in six or seven genera. 

Hamsters are crepuscular. In the wild, they burrow underground in the daylight to avoid being caught by predators. Their diet contains a variety of foods, including dried food, berries, nuts, fresh fruits and vegetables. In the wild they will eat any wheat, nuts and small bits of fruit and vegetables that they might find lying around on the ground, and will occasionally eat small insects such as small fruit flies, crickets, and meal worms. They have elongated fur-lined pouches on both sides of their heads that extend to their shoulders, which they stuff full of food to be stored, brought back to the colony or to be eaten later.

Although the Golden Hamster (Mesocricetus auratus) was first described scientifically in 1839, it was not until 1930 that researchers were able to successfully breed and domesticate hamsters  Pet Syrian hamsters are descended from hamsters first found and captured in Syria by zoologist Israel Aharon 

Hamster behaviour can vary depending on their environment, genetics, and interaction with people. Because they are easy to breed in captivity, hamsters are often used as lab animals in more economically developed countries. Hamsters have also become established as popular small house pets 

Gorilla, Wild animals

Hi, guys! I've just done my biology and there was an article about gorillas. I was very excited and decided to tell you about it, too.

Gorillas are the largest of the living primates. They are ground-dwelling and predominantly herbivorous. They inhabit the forests of central Africa. Gorillas are divided into two species and (still under debate as of 2008) either four or five subspecies. The DNA of gorillas is 98%–99% identical to that of a human,[2] and they are the next closest living relatives to humans after the two chimpanzee species.

Gorillas live in tropical or subtropical forests. Although their range covers a small percentage of Africa, gorillas cover a wide range of elevations. The Mountain Gorilla inhabits the Albertine Rift montane cloud forests of the Virunga Volcanoes, ranging in altitude from 2,200–4,300 metres (7,200–14,100 ft). Lowland Gorillas live in dense forests and lowland swamps and marshes as low as sea level.

Evolution and classification

Female gorilla.

The closest relatives of gorillas are chimpanzees and humans, from which gorillas diverged about 7 million years ago.[5] Human genes differ only 1.6% on average from their corresponding gorilla genes in their sequence, but there is further difference in how many copies each gene has.[6]

Until recently there was considered to be a single gorilla species, with three subspecies: the Western Lowland Gorilla, the Eastern Lowland Gorilla and the Mountain Gorilla.[7][8] There is now agreement that there are two species with two subspecies each. More recently it has been claimed that a third subspecies exists in one of the species.

Primatologists continue to explore the relationships between various gorilla populations.[7] The species and subspecies listed here are the ones upon which most scientists agree.[citation needed]
Genus Gorilla   
Western Gorilla (Gorilla gorilla)
Western Lowland Gorilla (Gorilla gorilla gorilla)
Cross River Gorilla (Gorilla gorilla diehli)
Eastern Gorilla (Gorilla beringei)
Mountain Gorilla (Gorilla beringei beringei)
Eastern Lowland Gorilla (Gorilla beringei graueri)

The proposed third subspecies of Gorilla beringei, which has not yet received a trinomen, is the Bwindi population of the Mountain Gorilla, sometimes called the Bwindi Gorilla.
Physical characteristics


Two Western Lowland Gorillas move around at Ueno Zoo.

Gorillas move around by knuckle-walking. Adult males range in height from 1.65–1.75 metres (5 ft 5 in–5 ft 9 in), and in weight from 140–200 kg (310–440 lb). Adult females are often half the size of a silverback, averaging about 1.4 metres (4 ft 7 in) tall and 100 kg (220 lb). Occasionally, a silverback of over 1.8 metres (5 ft 11 in) and 230 kg (510 lb) has been recorded in the wild. However, obese gorillas in captivity have reached a weight of 270 kg (600 lb).[9] Gorillas have a facial structure which is described as mandibular prognathism, that is, their mandible protrudes farther out than the maxilla.

The Eastern Gorilla is more darkly colored than the Western Gorilla, with the Mountain Gorilla being the darkest of all. The Mountain Gorilla also has the thickest hair. The Western Lowland Gorilla can be brown or grayish with a reddish forehead. In addition, gorillas that live in lowland forests are more slender and agile than the more bulky Mountain Gorilla Almost all gorillas share the same blood type (B)  and, like humans, have individual finger prints.[12]
Behavior
Group life
"Blackback" redirects here. For other uses, see Blackback (disambiguation).
"Silverback" redirects here. For other uses, see Silverback (disambiguation).

A silverback is an adult male gorilla, typically more than 12 years of age and named for the distinctive patch of silver hair on his back. A silverback gorilla has large canine teeth that come with maturity. Blackbacks are sexually mature males of up to 11 years of age.

A silverback gorilla portrait.

Silverbacks are the strong, dominant troop leaders. Each typically leads a troop (group size ranges from 5 to 30) and is in the center of the troop's attention, making all the decisions, mediating conflicts, determining the movements of the group, leading the others to feeding sites and taking responsibility for the safety and well-being of the troop. Blackbacks may serve as backup protection.

Males will slowly begin to leave their original troop when they are about 11 years old, traveling alone or with a group of other males for 2–5 years before being able to attract females to form a new group and start breeding. While infant gorillas normally stay with their mother for 3–4 years, silverbacks will care for weaned young orphans, though never to the extent of carrying the little gorillas. If challenged by a younger or even by an outsider male, a silverback will scream, beat his chest, break branches, bare his teeth, then charge forward. Sometimes a younger male in the group can take over leadership from an old male. If the leader is killed by disease, accident, fighting or poachers, the group will split up, as the animals disperse to look for a new protective male. Occasionally, a group may be taken over in its entirety by another male. There is a strong risk that the new male will kill the infants of the dead silverback.
Food and foraging

Female and baby gorillas.

Gorillas are herbivores  eating fruits, leaves, and shoots. Further they are classified as foliovores. Much like other animals that feed on plants and shoots, they sometimes ingest small insects as well (however there has been video proof that gorillas do eat ants and termites much in the same way as chimpanzees.)   Gorillas spend most of the day eating. Their large sagittal crest and long canines allow them to crush hard plants like bamboo. Lowland gorillas feed mainly on fruit while Mountain gorillas feed mostly on herbs, stems and roots. 
Reproduction and lifespan

Gestation is 8½ months. There are typically 3 to 4 years between births. Infants stay with their mothers for 3–4 years. Females mature at 10–12 years (earlier in captivity); males at 11–13 years. Lifespan is between 30–50 years, although there have been exceptions. For example the Dallas Zoo's Jenny lived to the age of 55.[15][16][17] Recently, gorillas have been observed engaging in face-to-face sex, a trait that was once considered unique to humans and the Bonobo.