Rockhopper penguin
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What is a rockhopper penguin?
The rockhopper penguin is a crested penguin with red eyes and upright yellow feathers extending from its bill to the back of its head. Once considered a single species (E. chrysocome), they are now divided into two distinct species: the northern rockhopper penguin (E. moseleyi) and the southern rockhopper penguin.
Their combined geographic range includes many subantarctic and cool-temperate islands. They nest in colonies, with northern colonies ranging from 32,000 to 65,000 breeding pairs and southern colonies having upwards of 130,000 breeding pairs. Rockhopper penguins primarily eat krill, but they will also eat other crustaceans and cephalopods. They can dive up to 100 metres (330 feet) in search of food.
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Where do rockhopper penguins live?
Rockhopper penguins live on subantarctic and cool-temperate islands. Northern rockhopper penguins inhabit the Tristan da Cunha island group in the South Atlantic Ocean, as well as St. Paul Island and Nouvelle Amsterdam in the Indian Ocean. Southern rockhopper penguins concentrate in the Falkland Islands and islands near South America’s Cape Horn. They also inhabit Prince Edward and Marion islands, the Crozet Islands, the Kerguelen Islands in the Indian Ocean, and Macquarie and Campbell Island in the Southern Ocean. The IUCN’s Red List of Threatened Species classifies the northern rockhopper penguin as endangered and the southern rockhopper penguin as vulnerable.
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What do rockhopper penguins look like?
Adult rockhopper penguins are small, generally under 22 inches tall and weigh around 5.5 to 6.6 pounds. Though males are slightly larger, both sexes have red eyes, a red-brown beak, and noticeable superciliary stripes. These stripes are thin, upright yellow feathers extending from the beak to the back of the head above each eye.
Their heads, throats, and backs are covered in black feathers, contrasting with their white undersides. They also have a crest of black feathers that stands upright on the top of their heads.
Juveniles are similar to adults but may have lighter-colored or no superciliary stripes and mottled gray plumage under the chin. Rockhopper chicks have a black bill, gray plumage on their head and back, and a white underside. Northern rockhopper penguins are set apart by their slightly thicker superciliary stripe.
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What do rockhopper penguins eat?
Rockhopper penguins mainly eat krill, but they also eat other crustaceans and cephalopods to supplement their diet. Adult rockhopper penguins can dive as deep as 100 metres (330 feet) to find food.
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How do rockhopper penguins care for their young?
Rockhopper penguins nest in colonies of tens of thousands of breeding pairs. Northern rockhopper penguins gather in colonies along rocky shores to breed between mid-July and mid-August. Around mid-September, the egg laying peaks, with two eggs produced.
For 32–33 days, males and females take turns incubating the eggs. After the chicks hatch, this alternating feeding and guarding continues until the chicks are about 25 days old. The surviving young then join a group for protection while their parents look for food. After about 66 days, the young are old enough to leave the nest.
Southern rockhopper penguins follow a similar reproductive pattern. However, adult penguins return to their colonies in late October, egg laying peaks around mid-December, and the surviving young are fully independent at 70 days. Both adults and juveniles are preyed upon by seals at sea. Eggs and chicks are food for several birds.
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What special behaviors help rockhopper penguins survive in their environment?
Rockhopper penguins have several special behaviors that aid their survival. They nest in colonies of tens of thousands, which may offer protection from predators. They are agile among rocks, and can run with surprising speed despite their short legs, using their flippers for balance. When moving fast in the water, they leap to breathe. Both parents take turns incubating eggs and caring for chicks, and the young form protective crèches while parents forage. They can also orient themselves using the sun and recognize shoreline features to return to colonies. They supplement their diet with crustaceans and cephalopods, diving as deep as 100 metres (330 feet) in search of food.
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Rockhopper penguin, either of two species of crested penguins (genus Eudyptes, order Sphenisciformes) characterized by its red eyes, a relatively thin stripe of upright yellow feathers extending from the bill to the back of the head above each eye (the superciliary stripe), and a crest of black feathers that stands upright on the top of the head.
Rockhopper penguins were once part of a single species, E. chrysocome, which was separated into three subspecies—a northern group (E. chrysocome moseleyi), a southern group (E. chrysocome chrysocome), and an eastern group (E. chrysocome filholi). However, their geographic isolation from one another paired with the results of a study conducted in 2006 by French ecologist Pierre Jouventin, which noted several genetic and behavioral differences between E. chrysocome moseleyi, on one hand, and E. chrysocome chrysocome and E. chrysocome filholi, on the other, supported the separation of rockhopper penguins into two distinct species. At present the species is divided into northern rockhopper penguins (E. moseleyi) and southern rockhopper penguins (E. chrysocome).
Distribution
The combined geographic range of both species encompasses many subantarctic and cool-temperate islands, as well as a number of offshore islands in the Tierra del Fuego archipelago. Breeding populations of northern rockhopper penguins occur on the Tristan da Cunha island group in the South Atlantic Ocean and St. Paul Island and Nouvelle Amsterdam in the Indian Ocean. In contrast, southern rockhopper penguins are most concentrated in the Falkland Islands and on islands located along South America’s extreme southern coast near Cape Horn. Additional southern rockhopper colonies occur on Prince Edward and Marion islands, the Crozet Islands, and the Kerguelen Islands in the Indian Ocean and Macquarie Island and Campbell Island in the Southern Ocean.
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Physical features
Adults of both species are small in stature compared with other penguins. Most adults stand under 52–55 cm (about 20–22 inches) tall and weigh 2.5–3 kg (5.5–6.6 pounds). Although males are slightly larger than females, adult members of both sexes have red eyes, a red-brown beak, and prominent superciliary stripes, in addition to black feathers on their head, throat, and back that contrast with their white underside. Juveniles resemble adults in most respects. Some juveniles have lighter-coloured superciliary stripes, whereas other juveniles have no stripes at all. All juveniles possess mottled gray plumage underneath the chin. Rockhopper chicks, however, have a black bill, gray plumage on the head and back, and a white underside. The outward appearance of northern rockhopper penguins is distinguished from that of southern rockhopper penguins by the presence of a slightly thicker superciliary stripe.
Predators and prey
Rockhopper penguins rely on krill but also supplement their diets with other crustaceans and cephalopods. Adults may dive to 100 metres (330 feet) in search of food. Adults and juveniles of both species are preyed upon by southern sea lions (Otaria flavescens), leopard seals (Hydrurga leptonyx), and southern fur seals (Arctocephalus) at sea. Eggs and chicks are food for several birds—including giant fulmars (Macronectes giganteus), kelp gulls (Larus dominicanus), and skuas (Catharacta).
Nesting and breeding
Both species nest in colonies composed of tens of thousands of breeding pairs. The largest colonies of northern rockhopper penguins are located on Gough Island (with 32,000–65,000 breeding pairs) and Inaccessible Island (with 18,000–27,000 breeding pairs) in the Tristan da Cunha island group and Nouvelle Amsterdam Island (with about 25,000 breeding pairs). Colonies of southern rockhopper penguins tend to be significantly larger, with some colonies containing more than 130,000 breeding pairs.
Such population differences in colony size between the species may be partially related to the differences in the number of chicks that survive to adulthood. Southern rockhopper pairs often raise two chicks per season, compared with only one chick for northern rockhopper pairs. In both species, females typically breed at age 4–5, whereas males breed at age 5–6. The average life span for individuals of both species is 10 years; however, some may live as long as 30.
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Between mid-July and mid-August, male and female northern rockhopper penguins congregate in large, congested colonies along rocky shores to breed. Egg laying peaks about mid-September, and two eggs are produced. For the next 32–33 days, males and females take turns incubating the eggs. This alternating feeding and guarding strategy continues after the chicks hatch until the chicks are about 25 days old. The surviving young then join a “crèche” (group) for protection while their parents forage for food in the ocean. In late December, after about 66 days of life, the young are old enough to leave the nest.
The pattern of reproduction in southern rockhopper penguins follows a similar course; however, there are some exceptions. Adult penguins return to their colonies in late October, the egg laying peaks about mid-December of each year, and the surviving young are fully independent at 70 days.
Conservation status
The IUCN’s Red List of Threatened Species has classified the northern rockhopper penguin as endangered since 2008 because of dramatic population declines on Gough Island (96 percent between 1962 and 2007) and Tristan da Cunha (98 percent between the 1880s and 2007). Drift net fishing, competition with the commercial fishing industry, and increased predation pressure by fur seals are often cited as causal factors.
Despite the existence of several colonies made up of hundreds of thousands of individuals, the southern rockhopper penguin is classified as a vulnerable species by the IUCN’s Red List. Between the 1930s and 2007, Falkland Islands populations have undergone severe population declines, which may equate to a loss of more than 55 percent of the global population between 1970 and 2000. Changes in marine food chains caused by overfishing and climate change may be responsible for much of this decline; however, ornithologists also cite pollution related to the extraction of fossil fuels as a significant factor.