Penguin - Penguin (English spelling)

Japanese: ペンギン - ぺんぎん（英語表記）penguin

A general term for seabirds belonging to the family Spheniscidae in the order Spheniscidae of the class Aves. Members of this family, Spheniscidae, are found only in the Southern Hemisphere, and are particularly abundant in the waters of the Antarctic and Sub-Antarctic Circles. They are about 40 to 112 centimeters long. Their feathers are short and dense, covering the whole body, their wings are fin-like, and their tails and legs are short. They use their fin-like wings to dive and catch and eat fish, zooplankton, and squid. They swim by lifting their neck out of the water, and can dive quickly and move through the water at high speeds, but they can also move by jumping out of the water into the air, taking in air, landing on the water, and then gaining momentum and jumping out of the water again, just like dolphins. As birds adapted to diving, they are not agile on land, but they move by standing upright and walking or hopping. On ice, they can also slide along, sliding with their chest and abdomen touching each other.

Penguins breed on every island in the Antarctic and Sub-Antarctic, with particularly large populations along the coasts of the Antarctic Peninsula and Antarctica. They also breed on islands in southern Australia and New Zealand, on islands off the southwest coast of southern Africa, in Patagonia at the southern tip of South America, and off the coasts of Peru and Chile. Their northernmost range is the tropical Galapagos Islands near the equator.

[Hiroshi Hasegawa]

Classification

There are 18 extant species in 6 genera. The largest species is the Emperor Penguin Aptenodytes fosteri , which grows to a height of 1 meter when standing upright. It is the only species that breeds in the interior of the continent during the Antarctic winter, and returns to its nesting site shortly after the sea freezes over. A single egg is laid in May or June, and the male carries it on his feet and continues to incubate it without food in the dark and bitter cold, which often drops to below -40°C. The female spends the winter at sea, but returns 7 or 8 weeks after laying the egg, takes turns incubating the egg with the male, and takes care of the hatched chicks. The chicks grow slowly in early spring, then grow rapidly, and become independent around the time of midsummer in the Antarctic. The King Penguin A. patagonica is the next largest species, growing to a height of about 80 centimeters. It breeds in colonies on sub-Antarctic islands. It nests in the shade of grass and lays a single egg. They lay eggs on their feet, incubate them, and raise their chicks in winter. They were once hunted in large numbers by humans and disappeared from some islands, but were later protected and have repopulated on some islands.

Yellow-browed penguins, Megadyptes antipodes , breed on the cold-water islands of southern New Zealand and the surrounding area. They live in these areas all year round, and in mid-September they come up onto grassy coastal slopes to lay two eggs. The nests are built in the shade, with grass covering the nesting area. This species nests in small, scattered groups, and does not form large, dense colonies.

The Adelie penguin genus Pygoscelis consists of three species: the Gentoo penguin P. papua , the Adelie penguin P. adeliae , and the Chinstrap penguin P. antarctica . They breed on islands in the Antarctic and Sub-Antarctic regions, and on the coasts of continents, and eat plankton and crustaceans, as well as young fish. The Gentoo penguin is the largest of these penguins, and builds nests using pebbles and grass, laying two eggs in early spring. The chicks become independent by autumn. The Chinstrap penguin breeds on the Antarctic Peninsula and several nearby islands, laying two eggs. The Adelie penguin breeds in a wide area, including the Sub-Antarctic region, and breeds in the deepest part of the Antarctic continent along with the Emperor penguin. They nest in particularly large groups. They build nests using pebbles, lay two eggs, and incubate the eggs lying on their side. This species is the most well studied, and in addition to their breeding ecology, their display behavior and communication have also been analyzed.

The genus Eudyptes has six species, all of which have a golden or deep yellow feather crest over their eyes. They breed on islands in the cold waters of the subantarctic and spend the winter in the warmer northern waters. They lay two eggs, the first of which is smaller than the second. Only one chick is raised. The males of this species are larger, especially in terms of their beaks. The macaroni penguin E. chrysolophus nests in large, tightly packed colonies on flat ground or rough slopes, often building nests in the shade of stones or grass. The royal penguin E. schlegeli , which some researchers treat as the same species as the macaroni penguin, breeds only on Macquarie Island in Australia. The rockhopper penguin E. crestatus breeds on islands in cold waters. They travel between their nests and the sea by hopping up and down steep rocky slopes. They build nests in the shade of rocks, stones, or grass and lay two eggs. There are three other species, all of which breed on islands near New Zealand and live a similar lifestyle.

The two smallest penguin species are classified in the genus Eudyptula . They are just over 40 centimetres long and are found off the southern coasts of New Zealand and Australia. They live in warm seas all year round and come up onto the shore at night to visit caves or burrows they have dug in the ground. They lay two eggs in a clutch, but sometimes three. They catch and eat fish.

The remaining group, the Humboldt penguin genus Spheniscus , includes four species and is the most northerly of the penguin genus, living in warm waters. They build their nests in the shade of grass or trees, or in holes in the ground to avoid strong sunlight. All species can dig holes using their beaks and feet. They usually raise two chicks. They also feed mainly on fish. The Magellanic penguin S. magellanicus breeds on the coasts from southern Chile to Patagonia. Their nesting sites vary from open coasts to grassy slopes and forests. Where there is shelter, they build their nests in the shade, and where there is no shelter, they dig their own shallow burrows. The Humboldt penguin S. humboldti breeds on the coasts of northern Chile to Peru, and nest in small groups in caves and holes. They depend on the abundant fish schools nourished by the Humboldt Current, which contributes to the deposition of guano. However, due to the excessive mining of guano in the past, their nesting sites have been lost, and their numbers are now declining. The Galapagos Islands, located at the end of the Humboldt Current, are home to the Galapagos penguin S. mendiculus . They nest alone or in small groups in caves on the coast.

The other species is the African penguin S. demersus , which breeds on the southern and southwestern coasts of South Africa. This species is also nourished by the Benguela Current. It takes advantage of the abundant fish population and contributes to the deposition of guano. They build nests by digging holes under rocks on bare ground or in the shade of sparse vegetation, and lay two eggs.

[Hiroshi Hasegawa]

Ecology

An interesting thing about penguin breeding is that chicks of species that breed in groups form dense clusters of chicks when they grow up; particularly large clusters are formed by Emperor penguins and Adélie penguins, which breed in the Antarctic. This is thought to be a way for them to protect themselves together from predators such as South Polar skuas and southern giant petrels, and to protect each other from the cold and blizzards. Parent birds come around the group of chicks and make cries to call their chicks and feed them. Chicks do not enter the water until their downy feathers have been replaced by their natural feathers. Parent birds molt their entire bodies in a short period after breeding. During this time they stay on land and do not feed. In this way, penguins have various adaptations to live in cold regions.

[Hiroshi Hasegawa]

Relationship with human life

Penguins were once hunted as food for humans, and the oil extracted from them was used. Their eggs were also collected and used as food. This large-scale hunting and killing has led to a decline in the number of penguins, especially in warm regions. Guano was also mined as a good fertilizer, and the Humboldt and Cape penguins, which dig burrows and breed there, lost their nesting sites and their populations declined. In recent years, every country has banned or restricted the capture of birds and has begun to protect them. However, another new problem has arisen. Oil pollution in the ocean can kill many seabirds at once. This has led to a significant decline in the number of Cape penguins. Another problem is friction with fishing, which not only causes seabirds to get caught in nets, but also causes humans to take the food that seabirds eat. If humans take too much Antarctic krill, it could affect not only whales and penguins that depend on it for their livelihoods, but could also change the biological community itself.

[Hiroshi Hasegawa]

Major penguin species [specimen illustration]
©Yoshitaka Morikami ">

Major penguin species [specimen illustration]

Adelie penguin
They live in colonies in Antarctica and the surrounding islands. Their heads and backs are dark black, and their chests and ventral sides are white. The white rings around their eyes are conspicuous. Total length is about 76cm. Penguin family ©Shogakukan ">

Adelie penguin

Adelie penguin parent and child
Penguin chicks do not enter the water until all the down on their bodies has been replaced with their natural feathers. The parents also molt completely in a short period of time after breeding, but during that time they stay on land and do not feed. ©Shogakukan ">

Adelie penguin parent and child

Adelie penguin flock
Along with the Emperor Penguin, they live in the deepest parts of the Antarctic continent and form large colonies .

Adelie penguin flock

Rockhopper penguin
It is found on cold sea islands in the Southern Hemisphere, such as the Falkland Islands and the Auckland Islands. It has yellow ornamental feathers above its red eyes. It climbs up and down rocky slopes by hopping. Total length 61cm. Penguin family ©Shogakukan Photo by Hideyuki Asakura ">

Rockhopper penguin

King Penguin
It is found on islands in the sub-Antarctic Ocean, such as the Falkland Islands and the Kerguelen Islands. The back of the head and neck and the upper part of the chest are orange. It is the second largest penguin. It is also called the king penguin. Total length is 95 cm. Family: Spheniscidae ©Shogakukan ">

King Penguin

Yellow-eyed Penguin
It is found in southern New Zealand and the surrounding islands in cold waters. Its head is yellowish-white and its eyes are yellow. It is also called the ground penguin. Total length 66cm. Spheniscidae ©Shogakukan ">

Yellow-eyed Penguin

Cape Penguin
Found only in the coastal areas of southern Africa. They have a lot of white on their face and red eyes. In recent years, their numbers have decreased due to the loss of nesting sites caused by the mining of guano (bird droppings). Total length: about 65 cm. Penguin family ©Shogakukan Photo by Hideyuki Asakura ">

Cape Penguin

Gentoo Penguin
They breed on islands in the Antarctic and Sub-Antarctic regions, as well as on the coasts of continents. They have a white band on their head connecting the eyes. The sides of their beak are orange. Total length is 75cm. Family: Penguins ©Shogakukan ">

Gentoo Penguin

Humboldt Penguin
Distributed on islands from Peru to northern Chile. Similar to the Cape penguin and Magellanic penguin of the same genus, but with more pink areas around the eyes and a thinner white band on the head. Total length about 70 cm. Penguin family ©Shogakukan Photo by Hideyuki Asakura ">

Humboldt Penguin

Magellanic Penguin
Found along the coast from southern Chile to southern Argentina. There are two black bands on the chest. Total length is about 71 cm. Penguin family ©Shogakukan Photo by Hideyuki Asakura ">

Magellanic Penguin

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

鳥綱ペンギン目ペンギン科に属する海鳥の総称。この科Spheniscidaeの仲間は、南半球だけに分布し、とくに南極および亜南極圏の海域に多く生息する。全長約40～112センチメートル。羽は短く密で、全身を覆い、翼はひれ状になり、尾と足は短い。ひれ状の翼を用いて潜水し、魚類や動物プランクトン、イカ類をとらえて食べる。頸(くび)から上を水から出して遊泳し、すばやく潜水して水中を高速で進むことができるが、ちょうどイルカのように水中から空中に飛び出し、空気を吸い込んで着水し、また勢いをつけて水から飛び出すことを繰り返して、移動することもある。潜水適応した鳥なので、地上では敏捷(びんしょう)ではないが、直立姿勢をとり、歩いたり跳ねたりして移動する。氷上では胸腹部をつけて、滑るようにはうこともある。

　南極圏・亜南極圏のどの島をとってもペンギンが繁殖しない所はなく、南極半島と南極大陸の沿岸には、とくに多くのペンギンが繁殖している。また、オーストラリア南部やニュージーランド付属の島嶼(とうしょ)、アフリカ南部・南西海岸の島、南アメリカ南端のパタゴニア、ペルーやチリ沿岸にも繁殖する。分布の最北は赤道付近の熱帯ガラパゴス諸島である。

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分類

現生種は6属18種に分類される。最大種はエンペラーペンギンAptenodytes fosteriで、直立姿勢で1メートルの高さになる。南極の冬に、大陸の奥地に入って繁殖するただ一つの種で、海が氷結してまもなく集団営巣地に戻る。5、6月に1卵を産卵し、雄はこれを足の上にのせ、しばしば零下40℃以下に下がる暗黒の酷寒の中で、絶食して抱卵を続ける。雌は海で越冬するが、産卵から7、8週間後になると戻り、雄と抱卵を交替し、孵化(ふか)した雛(ひな)の世話をする。雛は春先はゆっくり成長し、以後急速に大きくなり、南極が真夏を迎えるころひとり立ちする。キングペンギンA. patagonicaは次に大きい種で、高さ約80センチメートルになる。亜南極圏の島で集団繁殖する。草の陰に営巣し、1卵を産む。卵を足の上にのせて抱卵し、冬季に雛を育てる。かつて人間によって多量に捕殺され、いくつかの島では姿を消した。しかし、その後保護され、再定着した島もある。

　ニュージーランド南部とその周辺の冷海域の島にはキンメペンギンMegadyptes antipodesが繁殖する。周年この海域で生活し、9月なかばに、草のある海岸斜面にあがって2卵を産む。巣は物陰につくられ、草で産座が敷かれる。この種は、まばらで小さな集まりをつくって営巣し、密な大集団をつくることはない。

　アデリーペンギン属Pygoscelisは、ジェンツーペンギンP. papua、アデリーペンギンP. adeliae、ヒゲペンギンP. antarcticaの3種からなる。南極圏・亜南極圏の島や大陸沿岸で繁殖し、甲殻類プランクトンや稚魚を食べる。このうちジェンツーペンギンがいちばん大形で、小石や草を用いて巣をつくり、春先に2卵を産む。秋になるまでに雛は独立する。ヒゲペンギンは南極半島とその近くのいくつかの島で繁殖し、2卵を産む。アデリーペンギンは亜南極圏を含む広い地域で繁殖し、エンペラーペンギンとともに南極大陸のもっとも奥まで繁殖分布する。とくに大きな集団をつくって営巣する。小石を集めて巣をつくり2卵を産み、体を横にして卵を抱く。この種はもっともよく研究され、繁殖生態のほか、誇示行動、コミュニケーションについても解析されている。

　マカロニペンギン属Eudyptesは6種で、どれも目の上に金色あるいは濃い黄色の羽冠をもつ。亜南極圏の冷海域の島で繁殖し、冬季には北の暖かい海で過ごす。2卵を産み、初卵は第2卵よりも小さい。雛は1羽育つのみである。この仲間は雄のほうが体が大きく、とくに嘴(くちばし)は太い。マカロニペンギンE. chrysolophusは平地や荒れた斜面にきっちりまとまった大きな集団をつくって営巣し、石や草陰によく巣をつくる。研究者によってはマカロニペンギンと同一種として取り扱うロイヤルペンギンE. schlegeliは、オーストラリアのマックォーリー島でのみ繁殖する。イワトビペンギンE. crestatusは冷海の島で繁殖する。急峻(きゅうしゅん)な岩の斜面を跳びはねて登り降りし、巣と海とを往復する。岩や石、草の陰に巣をつくり、2卵を産む。このほかに3種あるが、すべてニュージーランド近海の島で繁殖し、似た生活をする。

　ペンギン類でもっとも小形の2種はコビトペンギン属Eudyptulaに分類される。これらは全長40センチメートル余りで、ニュージーランドとオーストラリア南岸に分布する。周年温暖な海にすみ、夜、海岸にあがって、洞や土中に掘った巣穴に通う。1腹2卵、ときに3卵を産むことがある。魚類をとらえて食べる。

　残る一つのグループはフンボルトペンギン属Spheniscusで、4種が含まれ、ペンギン類のなかでは北に分布し、温暖な海域で生活する。草や木の陰、土中の穴に巣をつくって、強い太陽光を避ける。どの種も嘴と足を使って穴を掘ることができる。普通、2羽の雛を育てる。これらもおもに魚類を食べる。マゼランペンギンS. magellanicusはチリ南部からパタゴニアにかけての海岸で繁殖する。営巣地は開けた海岸から、草地斜面、林とさまざまで、遮蔽(しゃへい)物がある所ではその陰に巣をつくり、そうでない所では浅い巣穴を自ら掘る。フンボルトペンギンS. humboldtiはチリ北部からペルーの海岸地方で繁殖し、洞や穴で小集団をつくって営巣する。フンボルト海流が養う豊富な魚群に依存して生活し、グアノの堆積(たいせき)に寄与してきた。しかし、かつてのグアノの乱掘によって営巣場所を奪われ、現在は数が少なくなっている。フンボルト海流の終点に位置するガラパゴス諸島にはガラパゴスペンギンS. mendiculusが生息する。海岸の洞穴で、単独または小さな集団をつくって営巣する。

　もう1種は南アフリカ南部・南西部の沿岸で繁殖するケープペンギンS. demersusである。この種もベンゲラ海流が養われる。豊かな魚類を利用し、グアノ堆積に寄与した。裸地で岩の下に穴を掘ったり、まばらに生える植生の陰を利用して巣をつくり、2卵を産む。

［長谷川博］

生態

ペンギン類の繁殖で興味深いのは、集団で繁殖する種の雛が、成長してから雛だけの密集した集合をつくることで、とくに、南極圏で繁殖するエンペラーペンギン、アデリーペンギンなどで大きな集合が形成される。これはオオトウゾクカモメやオオフルマカモメなどの捕食者から共同で身を守り、寒さやブリザードからお互いを守る意味をもつと考えられている。親鳥は、雛集団の周囲にきて鳴き声を発し、自分の雛を呼び出して給餌(きゅうじ)する。雛は全身の綿羽が本来の羽毛に生え換わるまで水には入らない。親鳥は繁殖のあと短期間に全身の換羽を行う。その間は陸にとどまり餌(えさ)をとることはない。このようにペンギンには、寒冷地で生活するためのさまざまな適応がみられる。

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人間生活との関係

ペンギン類はかつて人間の食料としてとらえられ、搾った油も利用された。卵も採集され、食料となった。こうした多量の捕殺によって、温暖な地方に生息するペンギンの数がとくに減少した。またグアノは良質の肥料として採掘され、そこに巣穴を掘って繁殖していたフンボルトペンギン、ケープペンギンは営巣場所を奪われ、減少した。近年ではどの国でも鳥類の捕獲を禁止・制限し、保護するようになった。しかし、別の新しい問題が生じている。海洋の油汚染は、多くの海鳥を一挙に殺してしまうことがある。ケープペンギンはこのために現在では数が著しく減ってしまった。もう一つは、漁業との摩擦で、海鳥が網にかかる事故だけでなく、海鳥の餌を人間がとってしまうということがあげられる。南極のオキアミを人間がとりすぎてしまえば、それに依存して生活するクジラ類やペンギン類などに限らず、ひいては生物群集そのものを変質させてしまうおそれがある。

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ペンギンのおもな種類〔標本画〕

アデリーペンギン

アデリーペンギンの親子

アデリーペンギンの群れ

イワトビペンギン

キングペンギン

キンメペンギン

ケープペンギン

ジェンツーペンギン

フンボルトペンギン

マゼランペンギン