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For other uses, see Penguin (disambiguation).

Penguins
Temporal range: Late Danian-Recent, 62–0 Ma Possible Cretaceous origin according to molecular data[1][2][3]
Penguin species of different genera; from top-left, clockwise: Emperor penguin (Aptenodytes forsteri), snares penguin (Eudyptes robustus), little penguin (Eudyptula minor), yellow-eyed penguin (Megadyptes antipodes), gentoo penguin (Pygoscelis papua), African penguin (Spheniscus demersus)
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Clade: Austrodyptornithes
Order: Sphenisciformes
Sharpe, 1891
Family: Spheniscidae
Bonaparte, 1831
Modern genera

Aptenodytes
Eudyptes
Eudyptula
Megadyptes
Pygoscelis
Spheniscus
For prehistoric genera, see Systematics

Breeding range of penguins, all species (aqua); some species have wider seasonal migration ranges

Penguins are a group of aquatic flightless birds from the order Sphenisciformes (/sfɪˈnɪsəfɔːrmiːz/) of the family Spheniscidae (/sfɪˈnɪsɪdiː, -daɪ/).[4] They live almost exclusively in the Southern Hemisphere: only one species, the Galápagos penguin, is found north of the Equator. Highly adapted for life in the ocean water, penguins have countershaded dark and white plumage and flippers for swimming. Most penguins feed on krill, fish, squid and other forms of sea life which they catch with their bills and swallow whole while swimming. A penguin has a spiny tongue and powerful jaws to grip slippery prey.[5]

They spend about half of their lives on land and the other half in the sea. The largest living species is the emperor penguin (Aptenodytes forsteri):[6] on average, adults are about 1.1 m (3 ft 7 in) tall and weigh 35 kg (77 lb). The smallest penguin species is the little blue penguin (Eudyptula minor), also known as the fairy penguin, which stands around 30–33 cm (12–13 in) tall and weighs 1.2–1.3 kg (2.6–2.9 lb).[7] Today, larger penguins generally inhabit colder regions, and smaller penguins inhabit regions with temperate or tropical climates. Some prehistoric penguin species were enormous: as tall or heavy as an adult human. There was a great diversity of species in subantarctic regions, and at least one giant species in a region around 2,000 km south of the equator 35 mya, during the Late Eocene, a climate decidedly warmer than today.[8]

Etymology

A group of emperor penguins (Aptenodytes forsteri) in Antarctica

The word penguin first appears in literature at the end of the 16th century as a synonym for the great auk.[9] When European explorers discovered what are today known as penguins in the Southern Hemisphere, they noticed their similar appearance to the great auk of the Northern Hemisphere and named them after this bird, although they are not closely related.[10]

The etymology of the word penguin is still debated. The English word is not apparently of French,[11] Breton[12] or Spanish[13] origin (the latter two are attributed to the French word pingouin), but first appears in English or Dutch.[14]

Some dictionaries suggest a derivation from Welsh pen, 'head' and gwyn, 'white',[15] including the Oxford English Dictionary, the American Heritage Dictionary,[16] the Century Dictionary[16] and Merriam-Webster,[17] on the basis that the name was originally applied to the great auk, either because it was found on White Head Island (Template:Lang-cy) in Newfoundland, or because it had white circles around its eyes (though the head was black).

An alternative etymology links the word to Latin pinguis, which means 'fat' or 'oil'.[18] Support for this etymology can be found in the alternative Germanic word for penguin, fettgans or 'fat-goose', and the related Dutch word vetgans.

Adult male penguins are sometimes called cocks, females sometimes called hens; a group of penguins on land is a waddle, and a group of penguins in the water is a raft.

Pinguinus

Main article: Great auk

Since 1871, the Latin word Pinguinus has been used in scientific classification to name the genus of the great auk (Pinguinus impennis, meaning "plump or fat without flight feathers"),[19] which became extinct in the mid-19th century.[9] As confirmed by a 2004 genetic study, the genus Pinguinus belongs in the family of the auks (Alcidae), within the order of the Charadriiformes.[20][21]

The birds currently known as penguins were discovered later and were so named by sailors because of their physical resemblance to the great auk. Despite this resemblance, however, they are not auks, and are not closely related to the great auk.[10][19] They do not belong in the genus Pinguinus, and are not classified in the same family and order as the great auk. They were classified in 1831 by Charles Lucien Bonaparte in several distinct genera within the family Spheniscidae and order Sphenisciformes.

Systematics and evolution

Living and recently extinct species

Adélie penguin (Pygoscelis adeliae) feeding young. Like its relatives, a neatly bi-coloured species with a head marking.
Magellanic penguins (Spheniscus magellanicus). The closed neck collar denotes this species.
Southern rockhopper penguin (Eudyptes chrysocome) displaying its distinctive crest
Two king penguins and one gentoo penguin on a beach on South Georgia, British overseas territory

The number of extant penguin species is debated. Depending on which authority is followed, penguin biodiversity varies between 17 and 20 living species, all in the subfamily Spheniscinae. Some sources consider the white-flippered penguin a separate Eudyptula species, while others treat it as a subspecies of the little blue penguin;[22][23] the actual situation seems to be more complicated.[24] Similarly, it is still unclear whether the royal penguin is a separate species or merely a color morph of the macaroni penguin. The status of the rockhopper penguins is also unclear.

Updated after Marples (1962),[25] Acosta Hospitaleche (2004),[26] and Ksepka et al. (2006).[3]

Subfamily Spheniscinae – modern penguins

Image Genus Species
Aptenodytes Miller, JF, 1778 – great penguins
Pygoscelis Wagler, 1832 – brush-tailed penguins
Eudyptula Bonaparte, 1856 – little penguins
Spheniscus Brisson 1760 – banded penguins
Megadyptes Milne-Edwards, 1880
Eudyptes Vieillot, 1816 – crested penguins

Fossil genera

Basal Sphenisciformes

Species Notes Source
Waimanu manneringi Slack et al. 2006
Muriwaimanu tuatahi Mayr et al. 2017
Sequiwaimanu roseae Mayr et al. 2017
Crossvallia unienwillia Jadwiszczak et al. 2013
?Crossvallia waiparensis Mayr et al. 2019
Petradyptes stonehousei Ksepka et al. 2023
Kaiika maxwelli Fordyce & Thoman 2011
Kumimanu biceae Mayr et al. 2017
Kumimanu fordecyi Ksepka et al. 2023
Kupoupou stilwelli Blokland et al. 2019

Advanced Sphenisciformes

Species Notes Source
Anthropornis nordenskjoldii Jadwiszczak et al. 2002
Anthropornis grandis Jadwiszczak et al. 2002
UCMP 321021 (Anthropornis sp.) Ksepka & Clarke, 2010
Palaeeudyptes antarcticus
Palaeeudyptes marplesi
Palaeeudyptes klekowskii Jadwiszczak et al. 2002
Palaeeudyptes gunnari May represent the opposite sex of P. klekowskii [1] Jadwiszczak et al. 2002
Chilean Palaeeudyptes
Burnside "Palaeeudyptes" Ksepka & Clarke, 2010
Duntroon "Palaeeudyptes" Ksepka & Clarke, 2010
Archaeospheniscus lowei Giovanardi et al. 2021
Archaeospheniscus lopdelli Giovanardi et al. 2021
Notodyptes wimani Formerly Archaeospheniscus Giovanardi et al. 2021
Delphinornis larseni Jadwiszczak et al. 2002
Delphinornis gracilis Jadwiszczak et al. 2002
Delphinornis arctowskii Jadwiszczak et al. 2002
Mesetaornis polaris Jadwiszczak et al. 2002
Marambiornis exilis Jadwiszczak et al. 2002
Aprosdokitos mikrotero Hospitaleche et al. 2017
Perudyptes devriesi Ksepka & Clarke, 2010
Eretiscus tonni Hospitaleche & Tambussi, 2008
Palaeospheniscus patagonicus Hospitaleche & Tambussi, 2008
Palaeospheniscus bilocular Hospitaleche & Tambussi, 2008
Palaeospheniscus bergi Hospitaleche & Tambussi, 2008
Paraptenodytes antarcticus Hospitaleche & Tambussi, 2008
Arthrodytes andrewsi Hospitaleche & Tambussi, 2008
Madrynornis mirandus Hospitaleche & Tambussi, 2008
Pachydyptes simpsoni Park & Fitzgerald, 2012
Pachydyptes ponderosus Giovanardi et al. 2021
Anthropodyptes gilli Park & Fitzgerald, 2012
Pseudaptenodytes macraei Park & Fitzgerald, 2012
Marambiornopsis sobrali Jadwiszczak et al. 2021
Icadyptes salasi Clarke et al. 2007
Kairuku waewaeroa Giovanardi et al. 2021
Kairuku grebneffi Giovanardi et al. 2021
Kairuku waitaki Giovanardi et al. 2021
Glenn Murray Kairuku Giovanardi et al. 2021
Platydyptes novaezealandiae Giovanardi et al. 2021
Platydyptes marplesi Giovanardi et al. 2021
Inkayacu paracasensis Clarke et al. 2010

Extinct species of extant genera

Species Notes Source
Spheniscus megaramphus Hospitaleche & Tambussi, 2008
Spheniscus urbinai Hospitaleche & Tambussi, 2008
Spheniscus chilensis Hospitaleche & Tambussi, 2008
Spheniscus muizoni Hospitaleche & Tambussi, 2008
Pygoscelis grandis Hospitaleche & Tambussi, 2008
Pygoscelis tyreei
Pygoscelis calderensis Hospitaleche & Tambussi, 2008
Eudyptes atatu Thomas et al. 2020
Eudyptes warhami Cole et al. 2019
Eudyptes calauina Hoffmeister et al. 2014
Eudyptula wilsonae Thomas et al. 2023
Megadyptes antipodes richdalei Cole et al. 2019
Megadyptes antipodes waitaha Cole et al. 2019
Aptenodytes ridgeni

Poorly understood taxa

Species Notes Source
Dege hendeyi
Inguza predemersus
Duntroonornis parvus
Nucleornis insolitus
Marplesornis novaezealandiae
Korora oliveri
Paraptenodytes robustus
Platydyptes amiesi
"Pakudyptes hakataramea" Also called the "Hakataramea Penguin" Ando, 2007 (unpublished)

Invalid taxa

Species Notes Source
Tonniornis mesetaensis Named on an isolated humerus which is unable to be compared to other species present in the same locality. Ksepka & Clarke, 2010
Tonniornis minimum Named on an isolated humerus which is unable to be compared to other species present in the same locality. Similar size to a specimen referred to Delphinornis larseni. Ksepka & Clarke, 2010
Tereingaornis moisleyi Genus is a nomen dubium due to lack of identifiable traits, but the specimen may belong to a new species (the Te Ringa Falls Penguin) Thomas et al. 2019
Wimanornis seymourensis Synonymous with Palaeeudypytes gunnari
Orthopteryx gigas Hospitaleche and Reguero, 2010
Ichtyopteryx gracilis Hospitaleche and Reguero, 2010
Palaeoapterodytes ictus Hospitaleche, 2010
Psuedaptenodytes minor Lack of diagnostic characteristics on the holotype Park & Fitzgerald, 2012

The Early Oligocene genus Cruschedula was formerly thought to belong to Spheniscidae; however, re-examination of the holotype in 1943 resulted in the genus being placed in Accipitridae.[28] Further examination in 1980 resulted in placement as Aves incertae sedis.[29]

Taxonomy

The family name of Spheniscidae was given by Charles Lucien Bonaparte from the genus Spheniscus,[30] the name of that genus comes from the Greek word σφήν sphēn "wedge" used for the shape of an African penguin's swimming flippers.[31]

Some recent sources[3][32] apply the phylogenetic taxon Spheniscidae to what here is referred to as Spheniscinae. Furthermore, they restrict the phylogenetic taxon Sphenisciformes to flightless taxa, and establish the phylogenetic taxon Pansphenisciformes as equivalent to the Linnean taxon Sphenisciformes,[32] i.e., including any flying basal "proto-penguins" to be discovered eventually. Given that neither the relationships of the penguin subfamilies to each other nor the placement of the penguins in the avian phylogeny is presently resolved, this is confusing, so the established Linnean system is followed here.

Evolution

Penguin tracks in the sand on Bruny Island, Tasmania

The evolutionary history of penguins is well-researched and represents a showcase of evolutionary biogeography. Although penguin bones of any one species vary much in size and few good specimens are known, the alpha taxonomy of many prehistoric forms still leaves much to be desired. Some seminal articles about penguin prehistory have been published since 2005;[3][33][34][35] the evolution of the living genera can be considered resolved by now.

The basal penguins lived around the time of the Cretaceous–Paleogene extinction event somewhere in the general area of (southern) New Zealand and Byrd Land, Antarctica.[3] Due to plate tectonics, these areas were at that time less than 1,500 kilometres (930 mi) apart rather than the 4,000 kilometres (2,500 mi) of today. The most recent common ancestor of penguins and their sister clade can be roughly dated to the Campanian–Maastrichtian boundary, around 70–68 mya.[33][35][36] What can be said as certainly as possible in the absence of direct (i.e., fossil) evidence is that, by the end of the Cretaceous, the penguin lineage must have been evolutionarily well distinct, though much less so morphologically.

Basal fossils

The oldest known fossil penguin species is Waimanu manneringi, which lived in the early Paleocene epoch of New Zealand, or about 62 mya.[35] While they were not as well-adapted to aquatic life as modern penguins, Waimanu were generally loon-like birds but already flightless, with short wings adapted for deep diving.[35] They swam on the surface using mainly their feet, but the wings were – as opposed to most other diving birds (both living and extinct) – already adapting to underwater locomotion.[37]

Perudyptes from northern Peru was dated to 42 mya. An unnamed fossil from Argentina proves that, by the Bartonian (Middle Eocene), some 39–38 mya,[38] primitive penguins had spread to South America and were in the process of expanding into Atlantic waters.[32]

Palaeeudyptines

During the Late Eocene and the Early Oligocene (40–30 mya), some lineages of gigantic penguins existed. Nordenskjoeld's giant penguin was the tallest, growing nearly 1.80 meters (5.9 feet) tall. The New Zealand giant penguin was probably the heaviest, weighing 80 kg or more. Both were found on New Zealand, the former also in the Antarctic farther eastwards.

Traditionally, most extinct species of penguins, giant or small, had been placed in the paraphyletic subfamily called Palaeeudyptinae. More recently, with new taxa being discovered and placed in the phylogeny if possible, it is becoming accepted that there were at least two major extinct lineages. One or two closely related ones occurred in Patagonia, and at least one other—which is or includes the paleeudyptines as recognized today – occurred on most Antarctic and Subantarctic coasts.

But size plasticity seems to have been great at this initial stage of penguin radiation: on Seymour Island, Antarctica, for example, around 10 known species of penguins ranging in size from medium to huge apparently coexisted some 35 mya during the Priabonian (Late Eocene).[39] It is not even known whether the gigantic palaeeudyptines constitute a monophyletic lineage, or whether gigantism was evolved independently in a much restricted Palaeeudyptinae and the Anthropornithinae – whether they were considered valid, or whether there was a wide size range present in the Palaeeudyptinae as delimited as is usually done these days (i.e., including Anthropornis nordenskjoeldi).[3] The oldest well-described giant penguin, the 5-foot (1.5 m)-tall Icadyptes salasi, actually occurred as far north as northern Peru about 36 mya.

In any case, the gigantic penguins had disappeared by the end of the Paleogene, around 25 mya. Their decline and disappearance coincided with the spread of the Squalodontoidea and other primitive, fish-eating toothed whales, which certainly competed with them for food, and were ultimately more successful.[33] A new lineage, the Paraptenodytes, which includes smaller but decidedly stout-legged forms, had already arisen in southernmost South America by that time. The early Neogene saw the emergence of yet another morphotype in the same area, the similarly sized but more gracile Palaeospheniscinae, as well as the radiation that gave rise to the penguin biodiversity of our time.

Origin and systematics of modern penguins

Modern penguins constitute two undisputed clades and another two more basal genera with more ambiguous relationships.[34] To help resolve the evolution of this order, 19 high-coverage genomes that, together with two previously published genomes, encompass all extant penguin species have been sequenced.[40] The origin of the Spheniscinae lies probably in the latest Paleogene and, geographically, it must have been much the same as the general area in which the order evolved: the oceans between the Australia-New Zealand region and the Antarctic.[33] Presumably diverging from other penguins around 40 mya,[33] it seems that the Spheniscinae were for quite some time limited to their ancestral area, as the well-researched deposits of the Antarctic Peninsula and Patagonia have not yielded Paleogene fossils of the subfamily. Also, the earliest spheniscine lineages are those with the most southern distribution.

The genus Aptenodytes appears to be the basalmost divergence among living penguins.[3][41] They have bright yellow-orange neck, breast, and bill patches; incubate by placing their eggs on their feet, and when they hatch the chicks are almost naked. This genus has a distribution centred on the Antarctic coasts and barely extends to some Subantarctic islands today.

Pygoscelis contains species with a fairly simple black-and-white head pattern; their distribution is intermediate, centred on Antarctic coasts but extending somewhat northwards from there. In external morphology, these apparently still resemble the common ancestor of the Spheniscinae, as Aptenodytes' autapomorphies are, in most cases, fairly pronounced adaptations related to that genus' extreme habitat conditions. As the former genus, Pygoscelis seems to have diverged during the Bartonian,[42] but the range expansion and radiation that led to the present-day diversity probably did not occur until much later; around the Burdigalian stage of the Early Miocene, roughly 20–15 mya.[33]

The genera Spheniscus and Eudyptula contain species with a mostly Subantarctic distribution centred on South America; some, however, range quite far northwards. They all lack carotenoid colouration and the former genus has a conspicuous banded head pattern; they are unique among living penguins by nesting in burrows. This group probably radiated eastwards with the Antarctic Circumpolar Current out of the ancestral range of modern penguins throughout the Chattian (Late Oligocene), starting approximately 28 mya.[33] While the two genera separated during this time, the present-day diversity is the result of a Pliocene radiation, taking place some 4–2 mya.[33]

The Megadyptes–Eudyptes clade occurs at similar latitudes (though not as far north as the Galápagos penguin), has its highest diversity in the New Zealand region, and represents a westward dispersal. They are characterized by hairy yellow ornamental head feathers; their bills are at least partly red. These two genera diverged apparently in the Middle Miocene (Langhian, roughly 15–14 mya), but again, the living species of Eudyptes are the product of a later radiation, stretching from about the late Tortonian (Late Miocene, 8 mya) to the end of the Pliocene.[33]

Geography

The geographical and temporal pattern of spheniscine evolution corresponds closely to two episodes of global cooling documented in the paleoclimatic record.[33] The emergence of the Subantarctic lineage at the end of the Bartonian corresponds with the onset of the slow period of cooling that eventually led to the ice ages some 35 million years later. With habitat on the Antarctic coasts declining, by the Priabonian more hospitable conditions for most penguins existed in the Subantarctic regions rather than in Antarctica itself.[43] Notably, the cold Antarctic Circumpolar Current also started as a continuous circumpolar flow only around 30 mya, on the one hand forcing the Antarctic cooling, and on the other facilitating the eastward expansion of Spheniscus to South America and eventually beyond.[33] Despite this, there is no fossil evidence to support the idea of crown radiation from the Antarctic continent in the Paleogene, although DNA study favors such a radiation.[43]

Later, an interspersed period of slight warming was ended by the Middle Miocene Climate Transition, a sharp drop in global average temperature from 14 to 12 mya, and similar abrupt cooling events followed at 8 mya and 4 mya; by the end of the Tortonian, the Antarctic ice sheet was already much like today in volume and extent. The emergence of most of today's Subantarctic penguin species almost certainly was caused by this sequence of Neogene climate shifts.

Relationship to other bird orders

Penguin ancestry beyond Waimanu remains unknown and not well-resolved by molecular or morphological analyses. The latter tend to be confounded by the strong adaptive autapomorphies of the Sphenisciformes; a sometimes perceived fairly close relationship between penguins and grebes is almost certainly an error based on both groups' strong diving adaptations, which are homoplasies. On the other hand, different DNA sequence datasets do not agree in detail with each other either.

Humboldt penguins in an aquarium. The penguin is an accomplished swimmer, having flippers instead of wings.

What seems clear is that penguins belong to a clade of Neoaves (living birds except for paleognaths and fowl) that comprises what is sometimes called "higher waterbirds" to distinguish them from the more ancient waterfowl. This group contains such birds as storks, rails, and the seabirds, with the possible exception of the Charadriiformes.[44]

Inside this group, penguin relationships are far less clear. Depending on the analysis and dataset, a close relationship to Ciconiiformes[35] or to Procellariiformes[33] has been suggested. Some think the penguin-like plotopterids (usually considered relatives of cormorants and anhingas) may actually be a sister group of the penguins and those penguins may have ultimately shared a common ancestor with the Pelecaniformes and consequently would have to be included in that order, or that the plotopterids were not as close to other pelecaniforms as generally assumed, which would necessitate splitting the traditional Pelecaniformes into three.[45]

A 2014 analysis of whole genomes of 48 representative bird species has concluded that penguins are the sister group of Procellariiformes,[46] from which they diverged about 60 million years ago (95% CI, 56.8-62.7).[47]

The distantly related puffins, which live in the North Pacific and North Atlantic, developed similar characteristics to survive in the Arctic and sub-Arctic environments. Like the penguins, puffins have a white chest, black back and short stubby wings providing excellent swimming ability in icy water. But, unlike penguins, puffins can fly, as flightless birds would not survive alongside land-based predators such as polar bears and foxes; there are no such predators in the Antarctic. Their similarities indicate that similar environments, although at great distances, can result in similar evolutionary developments, i.e. convergent evolution.[48]

Anatomy and physiology

Penguin wings have the same general bone structure as flighted birds, but the bones are shorter and stouter to allow them to serve as fins. 1). Humerus 2). Sesamoid Bone 3). Radius 4). Ulna 5). Radial Carpal bone 6). Carpometacarpus 7). Phalanges
Taxidermized penguin skin

Penguins are superbly adapted to aquatic life. Their wings have evolved to become flippers, useless for flight in the air. In the water, however, penguins are astonishingly agile. Penguins' swimming looks very similar to birds' flight in the air.[49] Within the smooth plumage a layer of air is preserved, ensuring buoyancy. The air layer also helps insulate the birds in cold waters. On land, penguins use their tails and wings to maintain balance for their upright stance.

All penguins are countershaded for camouflage – that is, they have black backs and wings with white fronts.[50] A predator looking up from below (such as an orca or a leopard seal) has difficulty distinguishing between a white penguin belly and the reflective water surface. The dark plumage on their backs camouflages them from above.

Gentoo penguins are the fastest underwater birds in the world. They are capable of reaching speeds up to 36 km (about 22 miles) per hour while searching for food or escaping from predators. They are also able to dive to depths of 170–200 meters (about 560–660 feet).[51] The small penguins do not usually dive deep; they catch their prey near the surface in dives that normally last only one or two minutes. Larger penguins can dive deep in case of need. Emperor penguins are the world's deepest-diving birds. They can dive to depths of approximately 550 meters (1,800 feet) while searching for food.[52]

Penguins either waddle on their feet or slide on their bellies across the snow while using their feet to propel and steer themselves, a movement called "tobogganing", which conserves energy while moving quickly. They also jump with both feet together if they want to move more quickly or cross steep or rocky terrain.

Penguins have an average sense of hearing for birds;[53] this is used by parents and chicks to locate one another in crowded colonies.[54] Their eyes are adapted for underwater vision and are their primary means of locating prey and avoiding predators; in air it has been suggested that they are nearsighted, although research has not supported this hypothesis.[55]

Gentoo penguin swimming underwater at the Nagasaki Penguin Aquarium

Penguins have a thick layer of insulating feathers that keeps them warm in water (heat loss in water is much greater than in air). The emperor penguin has a maximum feather density of about nine feathers per square centimeter which is actually much lower than other birds that live in antarctic environments. However, they have been identified as having at least four different types of feather: in addition to the traditional feather, the emperor has afterfeathers, plumules, and filoplumes. The afterfeathers are downy plumes that attach directly to the main feathers and were once believed to account for the bird's ability to conserve heat when under water; the plumules are small down feathers that attach directly to the skin, and are much more dense in penguins than other birds; lastly the filoplumes are small (less than 1 cm long) naked shafts that end in a splay of fibers— filoplumes were believed to give flying birds a sense of where their plumage was and whether or not it needed preening, so their presence in penguins may seem inconsistent, but penguins also preen extensively.[56]

The emperor penguin has the largest body mass of all penguins, which further reduces relative surface area and heat loss. They also are able to control blood flow to their extremities, reducing the amount of blood that gets cold, but still keeping the extremities from freezing. In the extreme cold of the Antarctic winter, the females are at sea fishing for food, leaving the males to brave the weather by themselves. They often huddle together to keep warm and rotate positions to make sure that each penguin gets a turn in the centre of the heat pack.

Calculations of the heat loss and retention ability of marine endotherms [57] suggest that most extant penguins are too small to survive in such cold environments.[58] In 2007, Thomas and Fordyce wrote about the "heterothermic loophole" that penguins utilize in order to survive in Antarctica.[59] All extant penguins, even those that live in warmer climates, have a counter-current heat exchanger called the humeral plexus. The flippers of penguins have at least three branches of the axillary artery, which allows cold blood to be heated by blood that has already been warmed and limits heat loss from the flippers. This system allows penguins to efficiently use their body heat and explains why such small animals can survive in the extreme cold.[60]

They can drink salt water because their supraorbital gland filters excess salt from the bloodstream.[61][62][63] The salt is excreted in a concentrated fluid from the nasal passages.

The great auk of the Northern Hemisphere, now extinct, was superficially similar to penguins, and the word penguin was originally used for that bird centuries ago. They are only distantly related to the penguins, but are an example of convergent evolution.[64]

Isabelline penguins

An isabelline Adélie penguin on Gourdin Island

Perhaps one in 50,000 penguins (of most species) are born with brown rather than black plumage. These are called isabelline penguins. Isabellinism is different from albinism. Isabelline penguins tend to live shorter lives than normal penguins, as they are not well-camouflaged against the deep and are often passed over as mates.

Distribution and habitat

See also: List of Sphenisciformes by population

Although almost all penguin species are native to the Southern Hemisphere, they are not found only in cold climates, such as Antarctica. In fact, only a few species of penguin actually live so far south. Several species live in the temperate zone;[65][failed verification] one, the Galápagos penguin, lives as far north as the Galápagos Islands, but this is only made possible by the cold, rich waters of the Antarctic Humboldt Current that flows around these islands.[66] Also, though the climate of the Arctic and Antarctic regions is similar, there are no penguins found in the Arctic.[67]

Gálapagos Penguins near Isabela Island

Several authors have suggested that penguins are a good example of Bergmann's Rule[68][69] where larger-bodied populations live at higher latitudes than smaller-bodied populations. There is some disagreement about this and several other authors have noted that there are fossil penguin species that contradict this hypothesis and that ocean currents and upwellings are likely to have had a greater effect on species diversity than latitude alone.[70][71]

Major populations of penguins are found in Angola, Antarctica, Argentina, Australia, Chile, Namibia, New Zealand, and South Africa.[72][73] Satellite images and photos released in 2018 show the population of 2 million in France's remote Ile aux Cochons has collapsed, with barely 200,000 remaining, according to a study published in Antarctic Science.[74]

Behaviour

Chinstrap penguins in Antarctica

Breeding

Gentoo penguin watching over a sleeping chick at Brown Bluff
Gentoo penguin watching over a sleeping chick at Brown Bluff

Penguins for the most part breed in large colonies, the exceptions being the yellow-eyed and Fiordland species; these colonies may range in size from as few as 100 pairs for gentoo penguins to several hundred thousand in the case of king, macaroni and chinstrap penguins.[75] Living in colonies results in a high level of social interaction between birds, which has led to a large repertoire of visual as well as vocal displays in all penguin species.[76] Agonistic displays are those intended to confront or drive off, or alternately appease and avoid conflict with, other individuals.[76]

Penguins form monogamous pairs for a breeding season, though the rate the same pair recouples varies drastically. Most penguins lay two eggs in a clutch, although the two largest species, the emperor and the king penguins, lay only one.[77] With the exception of the emperor penguin, where the male does it all, all penguins share the incubation duties.[78] These incubation shifts can last days and even weeks as one member of the pair feeds at sea.

Penguins generally only lay one brood; the exception is the little penguin, which can raise two or three broods in a season.[79]

Penguin eggs are smaller than any other bird species when compared proportionally to the weight of the parent birds; at 52 g (2 oz), the little penguin egg is 4.7% of its mothers' weight, and the 450 g (1 lb) emperor penguin egg is 2.3%.[77] The relatively thick shell forms between 10 and 16% of the weight of a penguin egg, presumably to reduce the effects of dehydration and to minimize the risk of breakage in an adverse nesting environment.[80] The yolk, too, is large and comprises 22–31% of the egg. Some yolk often remains when a chick is born, and is thought to help sustain the chick if the parents are delayed in returning with food.[81]

When emperor penguin mothers lose a chick, they sometimes attempt to "steal" another mother's chick, usually unsuccessfully as other females in the vicinity assist the defending mother in keeping her chick.[82] In some species, such as emperor and king penguins, the chicks assemble in large groups called crèches.

Conservation status

The majority of living penguin species have declining populations. According to the IUCN Red List, their conservation statuses range from Least Concern through to Endangered.

Species IUCN Red List Status Trend Mature Individuals Last assessment
Emperor penguin, Aptenodytes forsteri Near Threatened Unknown 2018[83]
King penguin, Aptenodytes patagonicus Least Concern Increasing 2018[84]
Little penguin, Eudyptula minor Least Concern Stable 469,760 2018[85]
Southern rockhopper penguin, Eudyptes chrysocome Vulnerable Decreasing 2,500,000 2018[86]
Macaroni penguin, Eudyptes chrysolophus Vulnerable Decreasing 2018[87]
Northern rockhopper penguin, Eudyptes moseleyi Endangered Decreasing 480,600 2018[88]
Fiordland penguin, Eudyptes pachyrynchus Vulnerable Decreasing 2,500-9,999 2018[89]
Snares penguin, Eudyptes robustus Vulnerable Stable 63,000 2018[90]
Royal penguin, Eudyptes schlegeli (disputed) Near Threatened Stable 1,700,000 2018[91]
Erect-crested penguin, Eudyptes sclateri Endangered Decreasing 150,000 2016[92]
Yellow-eyed penguin, Megadyptes antipodes Endangered Decreasing 2,528-3,480 2018[93]
Adélie penguin, Pygoscelis adeliae Least Concern Increasing 7,580,000 2018[94]
Chinstrap penguin, Pygoscelis antarctica Least Concern Decreasing 8,000,000 2018[95]
Gentoo penguin, Pygoscelis papua Least Concern Stable 774,000 2018[96]
African penguin, Spheniscus demersus Endangered Decreasing 50,000 2018[97]
Humboldt penguin, Spheniscus humboldti Vulnerable Decreasing 32,000 2018[98]
Magellanic penguin, Spheniscus magellanicus Near Threatened Decreasing 2018[99]
Galápagos penguin, Spheniscus mendiculus Endangered Decreasing 1,200 2018[100]

Penguins and humans

The cook on the Endurance preparing an emperor penguin for consumption.
An Adélie penguin encountering a human during the Antarctic summer

Penguins have no special fear of humans and will often approach groups of people. This is probably because penguins have no land predators in Antarctica or the nearby offshore islands. They are preyed upon by other birds like skuas, especially in eggs and as fledglings. Other birds like petrels, sheathbills, and gulls also eat the chicks. Dogs preyed upon penguins while they were allowed in Antarctica during the age of early human exploration as sled dogs, but dogs have long since been banned from Antarctica.[101] Instead, adult penguins are at risk at sea from predators such as sharks, orcas, and leopard seals. Typically, penguins do not approach closer than around 9 feet (2.7 meters), at which point they appear to become nervous.[102]

In June 2011, an emperor penguin came ashore on New Zealand's Peka Peka Beach, 3,200 kilometres (2,000 mi) off course on its journey to Antarctica.[103] Nicknamed Happy Feet, after the film of the same name, it was suffering from heat exhaustion and had to undergo a number of operations to remove objects like driftwood and sand from its stomach.[104] Happy Feet was a media sensation, with extensive coverage on TV and the web, including a live stream that had thousands of views[105] and a visit from English actor Stephen Fry.[106] Once he had recovered, Happy Feet was released back into the water south of New Zealand.[107]

Main article: Cultural depictions of penguins
Tux, the mascot of the Linux kernel

Penguins are widely considered endearing for their unusually upright, waddling gait, swimming ability and (compared to other birds) lack of fear of humans. Their black-and-white plumage is often likened to a white tie suit. Some writers and artists have penguins based at the North Pole, but there are no wild penguins in the Arctic. The cartoon series Chilly Willy helped perpetuate this myth, as the title penguin would interact with Arctic or sub-Arctic species, such as polar bears and walruses.

Penguins have been the subject of many books and films, such as Happy Feet, Surf's Up and Penguins of Madagascar, all CGI films; March of the Penguins, a documentary based on the migration process of the emperor penguin; and Farce of the Penguins, a parody of the documentary. Mr. Popper's Penguins is a children's book written by Richard and Florence Atwater; it was named a Newbery Honor Book in 1939. Penguins have also appeared in a number of cartoons and television dramas, including Pingu, created by Silvio Mazzola in 1986 and covering more than 100 short episodes. At the end of 2009, Entertainment Weekly put it on its end-of-the-decade "best-of" list, saying, "Whether they were walking (March of the Penguins), dancing (Happy Feet), or hanging ten (Surf's Up), these oddly adorable birds took flight at the box office all decade long."[108]

A video game called Pengo was released by Sega in 1982. Set in Antarctica, the player controls a penguin character who must navigate mazes of ice cubes. The player is rewarded with cut-scenes of animated penguins marching, dancing, saluting and playing peekaboo. Several remakes and enhanced editions have followed, most recently in 2012. Penguins are also sometimes depicted in music.[109]

In 1941, DC Comics introduced the avian-themed character of the Penguin as a supervillain adversary of the superhero Batman (Detective Comics #58). He became one of the most enduring enemies in Batman's rogues gallery. In the 60s Batman TV series, as played by Burgess Meredith, he was one of the most popular characters, and in Tim Burton's reimagining of the story, the character played by Danny Devito in the 1992 film Batman Returns, employed an actual army of penguins (mostly African penguins and king penguins).

Several pro, minor, college and high school sport teams in the United States have named themselves after the species, including the Pittsburgh Penguins team in the National Hockey League and the Youngstown State Penguins in college athletics.

Penguins featured regularly in the cartoons of U.K. cartoonist Steve Bell in his strip in The Guardian newspaper, particularly during and following the Falklands War. Opus the Penguin, from the cartoons of Berkeley Breathed, is also described as hailing from the Falklands. Opus was a comical, "existentialist" penguin character in the cartoons Bloom County, Outland and Opus. He was also the star in the animated Christmas TV special A Wish for Wings That Work.

In the mid-2000s, penguins became one of the most publicized species of animals that form lasting homosexual couples. A children's book, And Tango Makes Three, was written about one such penguin family in the New York Zoo.

References

  1. ^ Tambussi, C.; Hospitaleche, C. A. (2007). "Antarctic birds (Neornithes) during the Cretaceous–Eocene time" (PDF). Revista de la Asociación Geológica. 62 (4): 604–617. Archived (PDF) from the original on April 2, 2021. Retrieved March 21, 2021.
  2. ^ Hackett, S. J.; Kimball, R. T.; Reddy, S.; Bowie, R. C. K.; Braun, E. L.; Braun, M. J. (2008). "A Phylogenomic Study of Birds Reveals Their Evolutionary History". Science. 320 (5884): 1763–1768. Bibcode:2008Sci...320.1763H. doi:10.1126/science.1157704. PMID 18583609. S2CID 6472805.
  3. ^ a b c d e f g Ksepka, D. T.; Bertelli, S.; Giannini, N. P. (2006). "The phylogeny of the living and fossil Sphenisciformes (penguins)". Cladistics. 22 (#5): 412–441. doi:10.1111/j.1096-0031.2006.00116.x. S2CID 85673628.
  4. ^ Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (2023). "Kagu, Sunbittern, tropicbirds, loons, penguins". World Bird List Version 13.1. International Ornithologists' Union. Retrieved April 16, 2023.
  5. ^ "Diet and Eating Habits". Sea World Parks and Entertainment.
  6. ^ DK (2016). Animal!. Penguin. ISBN 9781465459008. Archived from the original on June 2, 2021. Retrieved November 18, 2020.
  7. ^ Grabski, Valerie (2009). "Little Penguin – Penguin Project". Penguin Sentinels/University of Washington. Archived from the original on December 16, 2011. Retrieved September 24, 2022.
  8. ^ Caballero, Rodrigo; Huber, Matthew (August 27, 2013). "State-dependent climate sensitivity in past warm climates and its implications for future climate projections". Proceedings of the National Academy of Sciences. 110 (35): 14162–14167. Bibcode:2013PNAS..11014162C. doi:10.1073/pnas.1303365110. ISSN 0027-8424. PMC 3761583. PMID 23918397.
  9. ^ a b Fuller, Errol (2003). The Great Auk: The Extinction of the Original Penguin. Bunker Hill Publishing, Inc. p. 17. ISBN 978-1-59373-003-1.
  10. ^ a b Crofford, Emily (1989). Gone Forever: The Great Auk. New York: Crestwood House. p. 10. ISBN 978-0-89686-459-7.
  11. ^ "PINGOUIN : Etymologie de PINGOUIN". Centre National de Ressources Textuelles et Lexicales. Archived from the original on October 26, 2008. Retrieved January 25, 2010.
  12. ^ Harper, Douglas. "penguin". Online Etymology Dictionary.
  13. ^ "Pingüino". Diccionario de la lengua española (in European Spanish) (22nd ed.). Real Academia Española. Archived from the original on June 9, 2011. Del fr. pingouin
  14. ^ "PINGOUIN : Etymologie de PINGOUIN". Centre National de Ressources Textuelles et Lexicales. Archived from the original on October 26, 2008. Retrieved January 25, 2010.
  15. ^ "penguin". Online Etymology Dictionary. Archived from the original on June 4, 2016. Retrieved April 29, 2016.
  16. ^ a b "penguin". Wordnik. Archived from the original on September 5, 2011. Retrieved October 7, 2014.
  17. ^ "Penguin – Definition". Merriam-Webster. August 31, 2012. Archived from the original on October 29, 2013. Retrieved September 8, 2013.
  18. ^ Tui De Roy; Mark Jones; Julie Cornthwaite (2013). Penguins:The Ultimate Guide. Princeton University Press. p. 151.
  19. ^ a b Gaskell, Jeremy (2000). Who Killed the Great Auk?. Oxford University Press (USA). p. 152. ISBN 0-19-856478-3. Archived from the original on October 18, 2021. Retrieved November 18, 2020.
  20. ^ Thomas, G. H.; Wills, M. A.; Székely, T. S. (2004). "A supertree approach to shorebird phylogeny". BMC Evolutionary Biology. 4: 28. doi:10.1186/1471-2148-4-28. PMC 515296. PMID 15329156.
  21. ^ Johnsgard, Paul A. (1987). Diving Birds of North America. Lincoln: University of Nebraska Press. pp. 265–266. ISBN 0-8032-2566-0. Retrieved May 11, 2010.
  22. ^ Williams
  23. ^ Davis; Lloyd S. & Renner; M. (1995). Penguins. London: T & A D Poyser. ISBN 0-7136-6550-5
  24. ^ Banks, Jonathan C.; Mitchell, Anthony D.; Waas, Joseph R. & Paterson, Adrian M. (2002). "An unexpected pattern of molecular divergence within the blue penguin (Eudyptula minor) complex" (PDF). Notornis. 49 (#1): 29–38. Archived from the original (PDF) on July 24, 2007.
  25. ^ Marples, B. J. (1962): Observations on the history of penguins. In: Leeper, G. W. (ed.), The evolution of living organisms. Melbourne, Melbourne University Press. pp. 408–416.
  26. ^ (in Spanish) Acosta Hospitaleche, Carolina (2004) Los pingüinos (Aves, Sphenisciformes) fósiles de Patagonia. Sistemática, biogeografía y evolución Archived September 15, 2014, at the Wayback Machine. Doctoral thesis, Department of Natural Sciences and Museum, Universidad Nacional de La Plata. La Plata, Argentina.
  27. ^ Cole, T.L.; Ksepka, D.T.; Mitchell, K.J.; Tennyson, A.J.; Thomas, D.B.; Pan, H.; Zhang, G.; Rawlence, N.J.; Wood, J.R.; Bover, P.; Bouzat, J.L. (2019). "Mitogenomes uncover extinct penguin taxa and reveal island formation as a key driver of speciation". Molecular Biology and Evolution. 36 (4): 784–797. doi:10.1093/molbev/msz017. PMID 30722030.
  28. ^ Simpson, G.G. (1946). "Fossil penguins" (PDF). Bulletin of the American Museum of Natural History. 81. Archived (PDF) from the original on August 11, 2007. Retrieved September 25, 2010.
  29. ^ Olson, S.L. (1985). "Faunal Turnover in South American Fossil Avifaunas: The Insufficiencies of the Fossil Record" (PDF). Evolution. 39 (5): 1174–1177. doi:10.2307/2408747. JSTOR 2408747. PMID 28561505. Archived (PDF) from the original on July 17, 2009. Retrieved September 25, 2010.
  30. ^ Fraser, Ian; Gray, Jeannie (2019). Australian Bird Names: Origins and Meanings. Clayton South, Victoria, Australia: CSIRO Publishing. pp. 86–87. ISBN 9781486311637.
  31. ^ Jobling, James A. (2010). The Helm Dictionary of Scientific Bird Names. London, England, UK: Helm Publishing. p. 361. ISBN 978-1-4081-2501-4.
  32. ^ a b c Clarke, Julia A.; Olivero, Eduardo B. & Puerta, Pablo (2003). "Description of the earliest fossil penguin from South America and first Paleogene vertebrate locality of Tierra Del Fuego, Argentina" (PDF). American Museum Novitates (3423): 1–18. doi:10.1206/0003-0082(2003)423<0001:dotefp>2.0.co;2. hdl:2246/2788. S2CID 19041678. Archived (PDF) from the original on July 24, 2007. Retrieved January 4, 2007.
  33. ^ a b c d e f g h i j k l Baker, A. J; Pereira, S. L.; Haddrath, O. P; Edge, K.-A. (2006). "Multiple gene evidence for expansion of extant penguins out of Antarctica due to global cooling". Proceedings of the Royal Society B: Biological Sciences. 273 (#1582): 11–7. doi:10.1098/rspb.2005.3260. PMC 1560011. PMID 16519228.
  34. ^ a b Bertelli, S.; Giannini, N. P. (2005). "A phylogeny of extant penguins (Aves: Sphenisciformes) combining morphology and mitochondrial sequences". Cladistics. 21 (3): 209–239. doi:10.1111/j.1096-0031.2005.00065.x. S2CID 85071808.
  35. ^ a b c d e Slack, Kerryn E.; Jones, Craig M.; Ando, Tatsuro; Harrison, G.L. "Abby"; Fordyce, R. Ewan; Arnason, Ulfur; Penny, David (2006). "Early Penguin Fossils, plus Mitochondrial Genomes, Calibrate Avian Evolution". Molecular Biology and Evolution. 23 (#6): 1144–1155. CiteSeerX 10.1.1.113.4549. doi:10.1093/molbev/msj124. PMID 16533822. Supplementary Material Archived December 16, 2009, at the Wayback Machine
  36. ^ The exact divergence dates according to Baker et al. (2006) mentioned in this section are not as precisely resolved, as it appears to be due to uncertainties of the molecular clock used.
  37. ^ Elliott, K. H.; Ricklefs, R. E.; Gaston, A. J.; Hatch, S. A.; Speakman, J. R.; Davoren, G. K. (2013). "High flight costs, but low dive costs, in auks support the biomechanical hypothesis for flightlessness in penguins". Proceedings of the National Academy of Sciences. 110 (#23): 9380–9384. Bibcode:2013PNAS..110.9380E. doi:10.1073/pnas.1304838110. PMC 3677478. PMID 23690614.
  38. ^ Contra Baker et al. (2006).
  39. ^ Jadwiszczak, Piotr (2006). "Eocene penguins of Seymour Island, Antarctica: taxonomy" (PDF). Polish Polar Research. 27 (#1): 3–62. Archived from the original (PDF) on July 24, 2007. Retrieved February 2, 2007.
  40. ^ Pan, Hailin; Cole, Theresa L.; Bi, Xupeng; Fang, Miaoquan; Zhou, Chengran; Yang, Zhengtao; Ksepka, Daniel T.; Hart, Tom; Bouzat, Juan L.; Argilla, Lisa S.; Bertelsen, Mads F. (September 1, 2019). "High-coverage genomes to elucidate the evolution of penguins". GigaScience. 8 (9). doi:10.1093/gigascience/giz117. PMC 6904868. PMID 31531675.
  41. ^ Christidis L, Boles WE (2008). Systematics and Taxonomy of Australian Birds. Canberra: CSIRO Publishing. p. 97. ISBN 978-0-643-06511-6.
  42. ^ It is likely that, during the Bartonian, there was a near-synchronous but allopatric split between the ancestors of Aptenodytes, Pygoscelis, and the common ancestor of all remaining genera (Baker).
  43. ^ a b Baker, A., Pereira, SL, Haddrath, OP, Edge, KA (2006). "Multiple gene evidence for expansion of extant penguins out of Antarctica due to global cooling". Proceedings of the Royal Society B: Biological Sciences. 273 (#1582): 11–7. doi:10.1098/rspb.2005.3260. PMC 1560011. PMID 16519228.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  44. ^ Fain, M. G.; Houde, P. (2004). "Parallel Radiations in the Primary Clades of Birds" (PDF). Evolution. 58 (11): 2558–73. doi:10.1554/04-235. PMID 15612298. S2CID 1296408. Archived from the original (PDF) on April 7, 2013.
  45. ^ Mayr, G. (2005). "Tertiary plotopterids (Aves, Plotopteridae) and a novel hypothesis on the phylogenetic relationships of penguins (Spheniscidae)" (PDF). Journal of Zoological Systematics and Evolutionary Research. 43: 61–71. doi:10.1111/j.1439-0469.2004.00291.x. Archived (PDF) from the original on October 13, 2006. Retrieved July 8, 2006.
  46. ^ Jarvis, E. D.; Mirarab, S.; Aberer, A. J.; Li, B.; Houde, P.; Li, C.; Ho, S. Y. W.; Faircloth, B. C.; Nabholz, B.; Howard, J. T.; Suh, A.; Weber, C. C.; Da Fonseca, R. R.; Li, J.; Zhang, F.; Li, H.; Zhou, L.; Narula, N.; Liu, L.; Ganapathy, G.; Boussau, B.; Bayzid, M. S.; Zavidovych, V.; Subramanian, S.; Gabaldon, T.; Capella-Gutierrez, S.; Huerta-Cepas, J.; Rekepalli, B.; Munch, K.; et al. (2014). "Whole-genome analyses resolve early branches in the tree of life of modern birds" (PDF). Science. 346 (#6215): 1320–1331. Bibcode:2014Sci...346.1320J. doi:10.1126/science.1253451. hdl:10072/67425. PMC 4405904. PMID 25504713. Archived from the original (PDF) on February 24, 2015. Retrieved August 28, 2015.
  47. ^ Li, C.; Zhang, Y.; Li, J.; Kong, L.; Hu, H.; Pan, H.; Xu, L.; Deng, Y.; Li, Q.; Jin, L.; Yu, H.; Chen, Y.; Liu, B.; Yang, L.; Liu, S.; Zhang, Y.; Lang, Y.; Xia, J.; He, W.; Shi, Q.; Subramanian, S.; Millar, C. D.; Meader, S.; Rands, C. M.; Fujita, M. K.; Greenwold, M. J.; Castoe, T. A.; Pollock, D. D.; Gu, W.; et al. (December 12, 2014). "Two Antarctic penguin genomes reveal insights into their evolutionary history and molecular changes related to the Antarctic environment". GigaScience. 3 (#1): 27. doi:10.1186/2047-217X-3-27. PMC 4322438. PMID 25671092.
  48. ^ Karleskint, George (2012). Introduction to Marine Biology. Cengage Publishing. p. 30. ISBN 978-1285402222. Archived from the original on July 21, 2020. Retrieved August 15, 2018.
  49. ^ "Penguin swimming under water, Galapagos". Youtube.com. April 14, 2008. Archived from the original on June 8, 2014. Retrieved September 8, 2013.
  50. ^ Buskey, Theresa (March 2001). "The Antarctic Polar Region". In Alan Christopherson, M.S. (ed.). The Polar Regions. LIFEPAC. 804 N. 2nd Ave. E., Rock Rapids, IA: Alpha Omegan Publications, Inc. ISBN 978-1-58095-156-2.{{cite book}}: CS1 maint: location (link)
  51. ^ Rafferty, John. "Gentoo Penguin". Britannica Online Encyclopedia. Encyclopedia Britannica Inc. Archived from the original on January 25, 2021. Retrieved January 20, 2021.
  52. ^ Rafferty, John. "Emperor Penguin". Britannica Online Encyclopedia. Britannica Encyclopedia Inc. Archived from the original on January 25, 2021. Retrieved January 20, 2021.
  53. ^ Wever, E. G.; Herman, P. N.; Simmons, J. A.; Hertzler, D. R. (1969). "Hearing in the blackfooted penguin, Spheniscus demersus, as represented by the cochlear potentials". Proceedings of the National Academy of Sciences of the United States of America. 63 (#3): 676–80. Bibcode:1969PNAS...63..676W. doi:10.1073/pnas.63.3.676. JSTOR 59401. PMC 223504. PMID 5259756.
  54. ^ Jouventin, P; Aubin, T; Lengagne, T (1999). "Finding a parent in a king penguin colony: The acoustic system of individual recognition". Animal Behaviour. 57 (#6): 1175–1183. doi:10.1006/anbe.1999.1086. PMID 10373249. S2CID 45578269.
  55. ^ Sivak, J; Howland, H. C.; McGill-Harelstad, P (1987). "Vision of the Humboldt penguin (Spheniscus humboldti) in air and water". Proceedings of the Royal Society of London B. 229 (#1257): 467–72. Bibcode:1987RSPSB.229..467S. doi:10.1098/rspb.1987.0005. JSTOR 36191. PMID 2881308. S2CID 32860474.
  56. ^ Ed Young (October 20, 2015). "Busting Myths About Penguin Feathers". National Geographic. Archived from the original on October 7, 2018. Retrieved October 7, 2018.
  57. ^ Downhower, J.F.; Blumer, L.S. (1988). "Calculating just how small a whale can be". Nature. 335 (#6192): 675. Bibcode:1988Natur.335..675D. doi:10.1038/335675b0. PMID 3173490. S2CID 47562824.
  58. ^ Williams, T.D. (1995). The penguins: Spheniscidae. New York: Oxford University Press.
  59. ^ Thomas, D.B.; Fordyce, R.E. (2007). "The heterothermic loophole exploited by penguins". Australian Journal of Zoology. 55 (#5): 317–321. doi:10.1071/zo07053.
  60. ^ Thomas, D.B.; Fordyce, R.E. (2012). "Biological plasticity in penguin heat-retention structures". Anatomical Record. 295 (#2): 249–256. doi:10.1002/ar.21538. PMID 22213564. S2CID 23175291.
  61. ^ "Animal Fact Sheets". Archived from the original on July 20, 2006. Retrieved July 21, 2006.
  62. ^ "Humboldt Penguin: Saint Louis Zoo". Archived from the original on September 28, 2006. Retrieved July 21, 2006.
  63. ^ van der Merwe, H.J. "African Penguins and Penguins of the World". iafrica.com. Archived from the original on October 12, 2006. Retrieved July 21, 2006.
  64. ^ Convergence and divergence in the evolution of aquatic birds Archived May 29, 2008, at the Wayback Machine by Marcel Van Tuinen, Dave Brian Butvill, John A. W. Kirsch and S. Blair Hedges.
  65. ^ Askew, Nick (June 24, 2009). "List of Penguin Species". BirdLife International. Archived from the original on August 22, 2016. Retrieved August 8, 2016.
  66. ^ Piper, Ross (2007), Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals, Greenwood Press.
  67. ^ Grobman, Arnold Brams (1964). Book: BSCS Biology, By Arnold Brams Grobman. Kendall/Hunt. ISBN 9780787290085. Archived from the original on October 18, 2021. Retrieved November 18, 2020.
  68. ^ Ashton, K. (2002). "Patterns of within-species body size variation of birds: strong evidence for Bergmann's rule". Global Ecology and Biogeography. 11 (#6): 505–523. Bibcode:2002GloEB..11..505A. doi:10.1046/j.1466-822X.2002.00313.x.
  69. ^ Meiri, S; Dayan, T. (2003). "On the validity of Bergmann's rule" (PDF). Journal of Biogeography. 30 (#3): 331–351. Bibcode:2003JBiog..30..331M. doi:10.1046/j.1365-2699.2003.00837.x. S2CID 11954818. Archived (PDF) from the original on September 24, 2015. Retrieved November 13, 2014.
  70. ^ Clarke, J. A.; Ksepka; Stucchi; Urbina; Giannini; Bertelli; Narváez; Boyd (2007). "Paleogene equatorial penguins challenge the proposed relationship between biogeography, diversity, and Cenozoic climate change". Proceedings of the National Academy of Sciences of the United States of America. 104 (#28): 11545–11550. Bibcode:2007PNAS..10411545C. doi:10.1073/pnas.0611099104. PMC 1913862. PMID 17601778.
  71. ^ Gohlich, U. B. (2007). "The oldest fossil record of the extant penguin genus Spheniscus – a new species from the Miocene of Peru". Acta Palaeontologica Polonica. 52: 285–298. Archived from the original on November 13, 2014. Retrieved November 13, 2014.
  72. ^ "Penguins of Australia and New Zealand". Southern Indian Education Center. Archived from the original on February 17, 2012. Retrieved September 8, 2013.
  73. ^ Jadwiszczak, P. (2009). "Penguin past: The current state of knowledge". Polish Polar Research. 30: 3–28. Archived from the original on March 7, 2022. Retrieved November 13, 2014.
  74. ^ "World's biggest king penguin colony shrinks 90 percent". World's biggest king penguin colony shrinks 90 percent (in Turkish). Archived from the original on August 1, 2018. Retrieved August 1, 2018.
  75. ^ Williams, p. 17
  76. ^ a b Williams, p. 57
  77. ^ a b Williams, p. 23
  78. ^ Numata, M.; Davis, L. S.; Renner, M. (2000). "Prolonged foraging trips and egg desertion in little penguins (Eudyptula minor)". New Zealand Journal of Zoology. 27 (#4): 277–289. doi:10.1080/03014223.2000.9518236.
  79. ^ Reilly PN, Balmford P (1975). "A breeding study of the little penguin, Eudyptula minor, in Australia". In Stonehouse, Bernard (ed.). The Biology of Penguins. London: Macmillan. pp. 161–87. ISBN 978-0-333-16791-5.
  80. ^ Meyer-Rochow V.B. (2015). "Examples of four incompletely resolved aspects of the biology of penguins elated to digestive and reproductive physiology, vision and locomotion". In Jenkins Owen P. (ed.). Advances in Animal Science and Zoology. Hauppauge, N.Y.: Nova Sci Publ Inc. pp. 65–80. ISBN 978-1-63483-328-8.
  81. ^ Williams, p. 24
  82. ^ Gorvett, Zaria (December 23, 2015). "If you think penguins are cute and cuddly, you're wrong". BBC Earth. Archived from the original on March 8, 2020. Retrieved March 9, 2020.
  83. ^ International), BirdLife International (BirdLife (May 1, 2004). "IUCN Red List of Threatened Species: Emperor Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  84. ^ International), BirdLife International (BirdLife (August 7, 2018). "IUCN Red List of Threatened Species: King Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  85. ^ International), BirdLife International (BirdLife (August 8, 2018). "IUCN Red List of Threatened Species: Little Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  86. ^ International), BirdLife International (BirdLife (August 7, 2018). "IUCN Red List of Threatened Species: Southern Rockhopper Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  87. ^ International), BirdLife International (BirdLife (August 7, 2018). "IUCN Red List of Threatened Species: Macaroni Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  88. ^ International), BirdLife International (BirdLife (August 7, 2018). "IUCN Red List of Threatened Species: Northern Rockhopper Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  89. ^ International), BirdLife International (BirdLife (August 7, 2018). "IUCN Red List of Threatened Species: Fiordland Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  90. ^ International), BirdLife International (BirdLife (August 7, 2018). "IUCN Red List of Threatened Species: Snares Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  91. ^ International), BirdLife International (BirdLife (August 7, 2018). "IUCN Red List of Threatened Species: Royal Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  92. ^ International), BirdLife International (BirdLife (October 1, 2016). "IUCN Red List of Threatened Species: Erect-crested Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  93. ^ International), BirdLife International (BirdLife (August 7, 2018). "IUCN Red List of Threatened Species: Yellow-eyed Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  94. ^ International), BirdLife International (BirdLife (August 7, 2018). "IUCN Red List of Threatened Species: Adelie Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  95. ^ International), BirdLife International (BirdLife (August 16, 2018). "IUCN Red List of Threatened Species: Chinstrap Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  96. ^ International), BirdLife International (BirdLife (August 7, 2018). "IUCN Red List of Threatened Species: Gentoo Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  97. ^ International), BirdLife International (BirdLife (August 8, 2018). "IUCN Red List of Threatened Species: African Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  98. ^ International), BirdLife International (BirdLife (August 9, 2018). "IUCN Red List of Threatened Species: Humboldt Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  99. ^ International), BirdLife International (BirdLife (August 9, 2018). "IUCN Red List of Threatened Species: Magellanic Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  100. ^ International), BirdLife International (BirdLife (August 9, 2018). "IUCN Red List of Threatened Species: Galapagos Penguin". IUCN Red List of Threatened Species. Archived from the original on March 4, 2020. Retrieved June 2, 2020.
  101. ^ "Removal of the sledge dogs from Antarctica". Natural Environment Research Council – British Antarctic Survey. Archived from the original on November 13, 2014.
  102. ^ "beautyofbirds.com". Beauty Of Birds. 2011. Archived from the original on April 17, 2021. Retrieved April 17, 2021.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  103. ^ "Emperor penguin not out of the woods yet". 3 News NZ. June 25, 2011. Archived from the original on December 10, 2013. Retrieved November 21, 2012.
  104. ^ "Happy Feet pulls through third operation". 3 News NZ. June 27, 2011. Archived from the original on December 14, 2011. Retrieved November 21, 2012.
  105. ^ "The truth about Happy Feet's home". 3 News NZ. August 8, 2011. Archived from the original on December 10, 2013. Retrieved November 21, 2012.
  106. ^ "Stephen Fry visits Happy Feet". 3 News NZ. August 11, 2011. Archived from the original on February 1, 2012. Retrieved November 21, 2012.
  107. ^ "Happy Feet starts the long journey home" (Video). 3 News NZ. August 29, 2011. Archived from the original on February 2, 2012. Retrieved November 21, 2012.
  108. ^ Geier, Thom; Jensen, Jeff; Jordan, Tina; Lyons, Margaret; Markovitz, Adam; Nashawaty, Chris; Pastorek, Whitney; Rice, Lynette; Rottenberg, Josh; Schwartz, Missy; Slezak, Michael; Snierson, Dan; Stack, Tim; Stroup, Kate; Tucker, Ken; Vary, Adam B.; Vozick-Levinson, Simon; Ward, Kate, "The 100 Greatest Movies, TV Shows, Albums, Books, Characters, Scenes, Episodes, Songs, Dresses, Music Videos, and Trends That Entertained Us Over the Past 10 Years" Archived April 15, 2014, at the Wayback Machine. Entertainment Weekly. December 11, 2009 (1079/1080):74-84
  109. ^ Shuker, R. (2012). Understanding popular music culture. Routledge.[ISBN missing][page needed]

Bibliography

Library resources about
Penguin
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