Young chicks are at much greater risk of predation than adults. Brown skuas (Catharacta lonnbergi) are the main predators of penguin chicks. Skuas mainly feed on the chicks and eggs found along the edge of the population which are perceived as weak and solitary. The formation of chick crèches act as an anti-predator-defense. Skuas are less likely to attack the crèches of gentoo chicks because it is hard to distinguish where one chick is within a group.
In the water, waddell seals (Leptonychotes weddellii) have been seen feeding on gentoos. Leopard seals (Hydrurga leptonyx) will travel in the gentoo breeding grounds and attack penguins leaving and returning to the colony. They are most often seen eating chicks as they first enter the water during fledging. Other species of seals such as fur seals from the genus Arctocephalus and southern sea-lions from the genus Otaria have been observed eating gentoos, although their impact on the population is unknown.
The main adaptation to evade predators is countershading. Aquatic predators can look down and see the black dorsal side of the gentoo, which blends in with the ocean floor. Likewise, seals looking up see the white ventral side, which blends in with the light from the sky.
Known Predators:
Anti-predator Adaptations: cryptic
Like all penguin species, the ventral side of gentoo penguins is white while the dorsal side is black. This color pattern is known as countershading. This adaptation is useful while swimming underwater; the lightly colored ventral side helps penguins blend in with the sky for predators or prey that are looking up. The dark dorsal side blends in with the ocean floor for predators or prey looking down.
The major difference between gentoo penguins and other penguin species are their head markings. Gentoos feature two white wedges around their eyes that are connected by a medium-sized line across the tops of their heads. Their heads are mostly covered in black feathers but small flecks of white feathers can also be found.
The feathers of gentoos are very fine; every square inch of their body can be covered with up to 70 feathers. Gentoos are part of a group called the "brush-tail penguins" which characterizes their tails as having longer feathers than those of other penguin species. Their tails consist of 14 to 18 feathers and are about 15 centimeters long. Because gentoos are aquatic, they must make their feathers waterproof. Using their bills, they do so by covering their feathers with oil found in the uropygial gland near the base of their tails.
Of the 17 penguin species, gentoo penguins are the third largest in size. They stand roughly at 76 centimeters when they reach adulthood. Depending on the time of the year, they can weigh anywhere from 4.5 to 8.5 kilograms. Heavier weights are seen during their month-long molting phase.
Their feet are stout, fat, and webbed. They are bright orange with long black claws extending from the webbing. The beak of a gentoo is partially black but has a bright dark-orange to red spot on either side. The color of the spot is attributed to the carotenoids absorbed from the krill they eat.
There is very little difference between the males and females. The main characteristic differentiating between the sexes is size. Males are significantly larger than females in almost all respects such as bill length, flipper length, and height.
Gentoo penguins look very similar from the time they hatch until their first molt which occurs at around 14 months. Chicks have downy-gray feathers and a weak, dull-colored bill. The white wedges around the eyes are noticeable at a young age; however, they are not as well-defined or connected along the top of their head like the adults.
Range mass: 4.5 to 8.5 kg.
Range length: 70 to 95 cm.
Average length: 75 cm.
Range wingspan: 22.2 to 25.6 cm.
Other Physical Features: endothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes alike; male larger
On average, gentoo penguins live to be 13 years old. Most deaths occur within the first year of life, with only a 30 to 50 percent chance of surviving until the next year. Beyond the first year, survival increases to an annual rate of 80 percent.
In captivity, the mean life span for P. papau is 10.5 years. Some individuals have lived to be older; however there are many deaths due to weather patterns (for outside exhibits) and for not maintaining a sufficient diet for the penguins.
Average lifespan
Status: wild: 13 years.
Average lifespan
Status: captivity: 10.5 years.
Gentoo penguins typically are found along the shoreline. This allows the penguins to be able to quickly access food while remaining close to their nest. They prefer elevations close to 115 meters above sea level along the shore because the snow in these areas tends to melt first. The higher the altitude, the decreased likelihood of nest-flooding as the snow starts to melt during the summer. The terrain in these areas is also flat which helps to stabilize their nests. Gentoo penguins prefer north-facing locations for nesting, which is thought to be linked to absorbing solar radiation. The main feature of gentoo habitats is the prevalence of small pebbles, typically under 5 centimeters in diameter. These pebbles are the main building blocks in creating a sufficient nest to hold the eggs during breeding season.
Gentoo penguins also spend some of their day underwater for feeding excursions. These aquatic trips are typically short; the longest dive on record is only two minutes long. Gentoos typically dive down only 3 to 20 meters, with occasional deeper dives up to 70 meters.
Average elevation: 115 m.
Range depth: 3.5 to 70.0 m.
Average depth: 9.0 m.
Habitat Regions: polar ; terrestrial ; saltwater or marine
Terrestrial Biomes: tundra ; icecap
Aquatic Biomes: coastal
Visually speaking, gentoo penguins see excellently underwater, although they are impaired when on land. Their retinas are very sensitive to the colors seen underwater such as green, blue, and purple. However this vision becomes impaired once they reach the surface of the water.
Gentoo penguins communicate with each other through a squawking vocalization. These calls typically are higher pitched and louder in males. Gentoos vocalize for a variety of reasons for example, when a male or female returns after feeding they will point their beaks straight up into the air and bellow out squawks to announce their return.
During incubation the parents take turns sitting on the eggs. When the other parent returns (mainly from feeding), a series of displays ensue. The arriving penguin does either a loud display in which he/she bellows out into the air or can do a bowing display in which the penguin bows down to the nest and gives a low hissing sound. Either of these displays communicates to the penguin on the egg that the returning penguin is ready to watch over the nest. The change-over of the nest between parents usually takes three minutes. Sometimes, the displays are reciprocated by the current incubator.
At times during the mating season, the male will rub the female's face and then the two of them will rub their bills together. Also, when one returns to the breeding ground with a stone to use for the nest, the other will bow repeatedly to accept the stone. These displays likely serve to strengthen the pair bond.
Gentoo penguins will also make sounds when another penguin is encroaching on its territory. Gentoos will make low hissing sounds if the interaction is not a high threat level. As a threat looms closer, gentoos will let out grunts.
Chicks communicate with their parents when they want food with high-pitched chirping sounds. In other situations, chicks make a modified whistle call until they reach their first molt where they develop the adult call. Chicks can distinguish their parents call apart from the calls of the thousands of other gentoos that may be nesting within the colony. Like all birds, gentoo penguins perceive their environments through visual, auditory, tactile, and chemical stimuli.
Communication Channels: visual ; tactile ; acoustic
Other Communication Modes: duets
Perception Channels: visual ; tactile ; acoustic ; chemical
The worldwide gentoo penguin population is stable with around 628,000 individuals. Some of these colonies are increasing moderately while others are declining rapidly. The constant, and sometimes drastic, changes in population size has gentoos listed as "Near Threatened" on the IUCN Red List. There are currently no conservation efforts in action, although some proposals suggest extending long-term observations on breeding colonies to limit disturbances of nesting sites. Protected areas have been set up in gentoo breeding grounds, including those on MacQuarie Island and Heard Island.
CITES: no special status
IUCN Red List of Threatened Species: near threatened
There are no known adverse effects of Pygoscelis papau on humans.
Penguins have been hunted for their blubber, which can be purified to oil and used for fuel. Hundreds of thousands of penguins were killed for their blubber, with some breeding colonies becoming obsolete. Gentoo skins are also collected and used to make caps, clothes, slippers, and purses. In the late 1980's, egg collecting was popular by sailors and by locals. These eggs also were consumed in large quantities.
Positive Impacts: body parts are source of valuable material
Gentoos live in colonies with other gentoos, but are also known to live in colonies with other penguin species. Although the species all forage in the ocean, different species are partitioned to forage at different depths or distances. P. papau do not negatively affect other penguin species since they mainly forage right offshore.
Because gentoos live in large colonies with thousands of birds, flea and tick prevalence is high. Fleas from the genus Parapsyllus are common. The most prevalent tick is Ixodes uriae, which mainly affects the exposed skin of chicks such as ear canals, feet, and faces.
Cestodes, members of the genus Tetrabothrius, have been found in the intestines of Pygoscelis papau but little is known about their life cycle. The cestodes are found in various crustaceans that make up the gentoos' diet. Members of the genus Corynosoma also have been reported in gentoos.
Parorchites zederi, another species of cestode, latches onto the inside of gentoos' intestines. These parasites create small pouches in the intestines and insert their pseudoscoleces ("false heads") in them to feed. The areas that P. zederi latch onto increase in volume due to the creation of more intestinal cells and blood flow to the area increases.
Commensal/Parasitic Species:
Gentoo penguins are carnivores and mainly consume fish, crustaceans, and cephalopods. Different times of the year mark different percentages of their diet. Krill (Euphausia vallentini) and shrimp (Nauticaris marioni) make up most of the crustacean diet. In February and March, crustaceans make up about 10% of their diet but from March to June it jumps to 75%. All other times of the year, crustaceans are absent from their diet.
From June to October, rockcod (Lepidonotothen squamifrons) make up 90% of their diet, but they also consume unicorn icefish (Channichthys rhinoceratus). Cephalopods only make up 10% of their diet during the year. The main types of cephalopods foraged on are octopi and sometimes small squid. The seasonal diet variation is due the presence of other penguin species during breeding season, seasonal migration of prey, as well as the availability of prey at varying depths. Most other penguins forage in deeper waters which will push some prey species closer to shore and into the prime range for gentoos.
Gentoo penguins feed in shallow regions. When they are underwater, their metabolic rate slows down enabling them to stay underwater for longer periods to forage.
During the chick-rearing stage, parent gentoos will return to the nest and regurgitate their freshly caught food for their chicks to eat.
Animal Foods: fish; mollusks; aquatic crustaceans
Primary Diet: carnivore (Piscivore )
Pygoscelis papua, or more commonly known as gentoo penguins, are exclusively found in the Southern Hemisphere between 45 and 65 degrees south latitude. Within this range, gentoos are found on the Antarctic Peninsula as well as many sub-Antarctic islands. Only about 13% of all gentoo penguins live south of the Antarctic ice pack.
One of the most predominant locations gentoos inhabit is the Falkland Islands in the South Atlantic Ocean. Around 40% of P. papua worldwide are found within this archipelago.
Biogeographic Regions: antarctica (Native )
Females' choice of male mates is based on male behaviors. First, the male gentoos find the best spot for a potential nest. The prime areas are those that are flat with little to no snow or ice. Once a potential nest site is chosen, the males point their bills vertically in the air and bellow out calls. The calls announce to the females to come and investigate their nest site. If a female waddles by and "likes" the nest site, the male and female will mutually display by trumpeting or bowing.
Gentoo penguins are monogamous during a breeding season, with some pair bonds lasting a lifetime. "Divorces" (the breaking of pair-bonds) do occur between breeding seasons. In this case, females choose a new partner that has displayed greater reproductive success. As colonial breeders, direct observation of nesting success is possible. The divorce rate in gentoos is less than 20 percent, which is relatively low compared to other penguin species. The benefit to a monogamous relationship is that mates do not have to expend time and energy finding new mates each year.
Mating System: monogamous
Gentoo penguins can begin breeding at two years of age, although most don't until they are about three or four. Living in colonies, gentoo penguins can gather in groups of over 2,000 pairs at one breeding site. At the beginning of the breeding season, nests are built by the parents. Gentoo nests are spaced about a meter apart. The egg-laying season for P. papau begins from June to mid-August and usually finishes in late October to late November.
After the nest has been completed, the female will stay at the nest and lay her egg 5 days post-breeding. A second egg is laid three days later. The eggs are spherical and greenish-white. The weight of the first egg in relation to the second egg varies between nesting locations, but on average egg weight is 125 grams. There have been rare cases where one or three eggs were laid.
If the set of eggs is lost, gentoo penguins can lay a second set of eggs during the same breeding season. These eggs are laid near the end of the breeding season when the female regains sufficient energy. The downside to a late laying is reduced energy, causing a late molting period. Females do not have enough energy to begin their molt right after breeding and therefore delay molting. This, in turn, delays egg-laying the following year. Indeed, the female may not have enough energy to lay a clutch the next year.
The eggs are incubated for an average of 35 days before hatching. Although the eggs are laid days apart from each other, they typically hatch on the same day or one day apart. The chicks are frail and weigh about 96 grams. The chicks stay at the nest for the first 75 days until they are ready to fledge and visit the ocean for the first time. During this fledging period, gentoo chicks make an average of 5 trips to sea. The young reach independence 20 days post-fledging.
Breeding interval: Gentoo penguins breed once a year.
Breeding season: The breeding season for gentoo penguins starts in June to mid-August and ends in late October to late November.
Range eggs per season: 1 to 3.
Range time to hatching: 34 to 35 days.
Average time to hatching: 37 days.
Range fledging age: 75 to 105 days.
Average fledging age: 80 days.
Range time to independence: 85 to 105 days.
Average time to independence: 100 days.
Range age at sexual or reproductive maturity (female): 2 to 3 years.
Average age at sexual or reproductive maturity (female): 2 years.
Range age at sexual or reproductive maturity (male): 2 to 3 years.
Average age at sexual or reproductive maturity (male): 2 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
Both parents are involved in nest-building. The nest is bowl shaped with a wide edge and a hollow center. Nest size ranges between 10 to 20 cm in height and around 45 cm in diameter. Nests are made from small stones found around the nesting site, including stones stolen from other nests. Medium-sized nests can contain over 1,700 pebbles. Although pebbles are the main component of nests, sometimes molted feathers, twigs, and vegetation are used.
Members of both sexes defend their nests from other birds that come too close. P. papau will stick out its bill toward the invader and let out a low hiss. Competition for territory exists between two adjacent nests in which parents will turn their neck towards their neighbor and try to grab and twist their bill. Although rare, fighting with bills and flippers has been observed.
The female lays two eggs within 3 days of each other. The eggs are kept safely under the male or female for the 35 days of incubation. For the first three to four weeks, the chicks are guarded in the nest. The parents take turns getting food and regurgitating it for the chicks. Near the end of this stage, the chicks begin to move short distances away from the nest and form groups with other chicks (creches). These groups serve to protect against predators while both parents to forage for the growing young. The young fledge at 70 days old and will enter the sea for the first time. Both parents will still feed their chicks (although not as often) during the fledging period. Feedings have occasionally been recorded post-independence.
Parental Investment: altricial ; male parental care ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Male, Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female); pre-independence (Provisioning: Male, Female)
The gentoo penguin (/ˈdʒɛntuː/ JEN-too) (Pygoscelis papua) is a penguin species (or possibly a species complex) in the genus Pygoscelis, most closely related to the Adélie penguin (P. adeliae) and the chinstrap penguin (P. antarcticus). The earliest scientific description was made in 1781 by Johann Reinhold Forster with a type locality in the Falkland Islands. The species calls in a variety of ways, but the most frequently heard is a loud trumpeting, which the bird emits with its head thrown back.[2]
The application of "gentoo" to the penguin is unclear. Gentoo was an Anglo-Indian term to distinguish Hindus from Muslims.[3] The English term may have originated from the Portuguese gentio ("pagan, gentile"). Some speculate that the white patch on the bird's head was thought to resemble a turban.[4]
It may also be a variation of another name for this bird, "Johnny penguin", with Johnny being Juanito in Spanish and sounds vaguely like gentoo.[5][6][7] The Johnny rook, a predator, is likely named after the Johnny penguin.[8]
The specific name papua is a misnomer; in the original description, Johann Reinhold Forster, a naturalist who had circumnavigated the world with Captain James Cook, mistakenly assumed that the species occurred in Papua (New Guinea), the closest gentoos being over 6000 km to the south (on Macquarie Island).[4] No penguins are found in New Guinea.[9] Others trace the error to a "possibly fraudulent claim" in 1776 by French naturalist Pierre Sonnerat, who also alleged a Papuan location for the king penguin despite never having been to the island himself.[10]
The gentoo penguin is one of three species in the genus Pygoscelis. Mitochondrial and nuclear DNA evidence suggests the genus split from other penguins around 38 million years ago (Mya), about 2 million years after the ancestors of the genus Aptenodytes. In turn, the Adélie penguins split off from the other members of the genus around 19 Mya and the chinstrap and gentoo finally diverged around 14 Mya.[11]
There are 4 subspecies recognized by the International Ornithological Congress:[12]
Although the population on the Kerguelen Islands is tentatively included in taeniata, it may also be a distinct subspecies.[13]
Before 2021, only two subspecies of the gentoo penguin have been recognised: P. p. papua (subantarctic gentoo) and the smaller P. p. ellsworthi (Antarctic gentoo).[14][15] However, a 2020 study suggested that the gentoo penguin be split into a species complex of four morphologically similar but separate species: the northern gentoo penguin (P. papua sensu stricto), the southern gentoo penguin (P. ellsworthi), the eastern gentoo penguin (P. taeniata) and the newly described South Georgia gentoo penguin (P. poncetii).[16][17] The International Ornithological Congress incorporated the results of this study in 2021, but relegated the newly recognized or newly described species to being subspecies of P. papua.[13]
The gentoo penguin is easily recognised by the wide, white stripe extending like a bonnet across the top of its head and its bright orange-red bill. It has pale whitish-pink, webbed feet and a fairly long tail – the most prominent tail of all penguin species. Chicks have grey backs with white fronts. As the gentoo penguin waddles along on land, its tail sticks out behind, sweeping from side to side, hence the scientific name Pygoscelis, which means "rump-tailed".[18]
Gentoo penguins can reach a length of 70 to 90 cm (28 to 35 in),[19][20] making them the third-largest species of penguin after the emperor penguin and the king penguin. Males have a maximum weight around 8.5 kg (19 lb) just before moulting and a minimum weight of about 4.9 kg (11 lb) just before mating. For females, the maximum weight is 8.2 kg (18 lb) just before moulting, but their weight drops to as little as 4.5 kg (9.9 lb) when guarding the chicks in the nest.[21] Birds from the north are on average 700 g (1.5 lb) heavier and 10 cm (3.9 in) longer than the southern birds. Southern gentoo penguins reach 75–80 cm (30–31 in) in length.[22] They are the fastest underwater swimmers of all penguins, reaching speeds up to 36 km/h (22 mph).[23] Gentoos are well adapted to extremely cold and harsh climates.
The breeding colonies of gentoo penguins are located on ice-free surfaces. Settlements can be located directly on the shoreline or considerably inland. They prefer shallow coastal areas and often nest between tufts of grass. In South Georgia, for example, breeding colonies are 2 km inland. In colonies farther inland, where the penguins nest in grassy areas, they shift location slightly yearly because the grass becomes trampled over time.
Gentoos breed on many subantarctic islands. The main colonies are on the Falkland Islands, South Georgia and the South Sandwich Islands and Kerguelen Islands; smaller colonies are found on: Macquarie Island, Heard Islands, Crozet Islands, South Shetland Islands and the Antarctic Peninsula. The total breeding population is estimated to be over 600,000 birds. Gentoos breed monogamously and infidelity is typically punished with banishment from the colony.[24] Nests are usually made from a roughly circular pile of stones and can be quite large, 20 cm (7.9 in) high and 25 cm (9.8 in) in diameter. The stones are jealously guarded, and their ownership can be the subject of noisy disputes and physical attacks between individuals. They are also prized by the females, even to the point that a male penguin can obtain the favours of a female by offering her a choice stone.
Two eggs are laid, both weighing around 130 g (4.6 oz). The parents share incubation, changing duty daily. The eggs hatch after 34 to 36 days. The chicks remain in the nests for around 30 days before joining other chicks in the colony and forming crèches. The chicks moult into subadult plumage and go out to sea at around 80 to 100 days.
Gentoos mainly live on crustaceans, such as krill and shrimp,[25] with fish and cephalopods[25] making up only about 15% and 10% of the diet respectively.[25] They are, however, opportunistic feeders and around the Falklands are known to take roughly equal proportions of fish (Patagonotothen sp., Thysanopsetta naresi, Micromesistius australis), squat lobsters (Munida gregaria) and squid (Loligo gahi, Gonatus antarcticus, Moroteuthis ingens). Other prey include Lepidonotothen squamifrons, Channichthys rhinoceratus and octopuses.[25]
The gentoos' diet is high in salt, as they eat organisms with relatively the same salinity as seawater, which can lead to complications associated with high sodium concentrations in the body, especially for gentoo chicks. To counteract this, gentoos, as well as many other marine bird species, have a highly developed salt gland located above their eyes that takes the high concentration of sodium within the body and produces a highly saline-concentrated solution that drips out of the body from the tip of the beak.[26]
Gentoo penguins do not store as much fat as Adélie penguins, their closest relative; gentoos require less energy investment when hunting because the net gain of energy after hunting is greater in gentoos than Adélies.[27] As embryos, gentoos require a lot of energy to develop. Oxygen consumption is high for a developing gentoo embryo. As the embryo grows and requires more oxygen, consumption increases exponentially until the gentoo chick hatches. By then, the chick is consuming around 1800 ml O2 per day.[28]
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In the sea, leopard seals, sea lions and killer whales are all predators of the gentoo. On land, no predators of full-grown, healthy gentoo penguins exist. Skuas and giant petrels regularly kill many chicks and steal eggs; petrels kill injured and sick adult gentoos. Various other seabirds, such as the kelp gull and snowy sheathbill, also snatch chicks and eggs. Skuas on King George Island have been observed attacking and injuring adult gentoo penguins in apparent territorial disputes.[29]
As of 2019, the IUCN Red List lists the gentoo as least concerned with a stable population trend, although rapid declines in some key areas are believed to be driving a moderate overall decline in the species population. Examples include Bird Island, South Georgia, where the population has fallen by two-thirds over 25 years.[1] Many threats to this species, including pollution, hunting, fishing and human recreational activities continue to affect them.[30]
The Linux distribution Gentoo Linux is named after the gentoo penguin. This is a nod to the fact that the penguin is the fastest swimming penguin, as Gentoo Linux aims to be a high-performance operating system.[31]: 383
Adult gentoo confronting a southern giant petrel (Macronectes giganteus) that has killed a chick
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Gentoo penguin on a nest
A gentoo penguin swimming
Juvenile gentoos on Petermann Island
Gentoo colony on Carcass Island in the Falklands
A leopard seal eating an adult gentoo
{{cite web}}: CS1 maint: multiple names: authors list (link) {{cite journal}}: CS1 maint: multiple names: authors list (link) This article incorporates text from the ARKive fact-file "Gentoo penguin" under the Creative Commons Attribution-ShareAlike 3.0 Unported License and the GFDL.
The gentoo penguin (/ˈdʒɛntuː/ JEN-too) (Pygoscelis papua) is a penguin species (or possibly a species complex) in the genus Pygoscelis, most closely related to the Adélie penguin (P. adeliae) and the chinstrap penguin (P. antarcticus). The earliest scientific description was made in 1781 by Johann Reinhold Forster with a type locality in the Falkland Islands. The species calls in a variety of ways, but the most frequently heard is a loud trumpeting, which the bird emits with its head thrown back.
