Rockhopper penguin
The Rockhopper penguin (scientific name: Eudyptes chrysocome) is one of seventeen species of flightless birds in the family of penguins. It is one of six "Crested Penguins" in the genus Eudyptes which also includes the Fiordland crested, Macaroni, Snares crested, Royal and Big-crested penguins..
 Source: Yan Ropert-Coudert/WoRMS/Encyclopedia of Life |
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Conservation Status  |
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Scientific Classification Kingdom: Animalia |
Like all penguins, the Rockhopper penguin is characterized by its erect posture, stiff wings, excellent swimming capability, awkward movement out of water, and distinctive coloration. The black back and white front, make all penguins difficult to see when swimming, blending against the sea from above and the sky from below.
The Rockhopper penguin are made up of three subspecies, each with a different geographic distribution:
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Contents
Physical Description
The Rockhopper penguin is one of the smallest of the penguin species. The characteristically robust body is white on the underside and slate-gray above, with a yellow line above the eye that extends into yellowish plumes. Behind the head there is also a crest of black feathers. The short bill is reddish brown in color and the eyes are red. Juveniles can be identified by the lack of adult yellow markings.
Rockhopper penguins measure about 55 centimeters in length and weigh around 2.5 kilograms. These birds stand upright on two short feet. Their legs are set far back on the body. The waterproof coat, composed of feathers that average 2.9 centimeters in length, is white on the underside and bluish-black on the top. The head has bright yellow plumage on the brow; the yellow feathers extend along the sides. The top of the head has spiked black feathers. The wings are strong, stiff, narrow and flipper-like. Rockhopper penguins have tiny eyes.
Diagnostic Description: Length: 66-76 cm. Plumage: adult with head, throat, back, wings, tail and under-tail coverts black, breast and white belly. Yellow line above eye does not meet on forehead, but ends in long, pale yellow plumes behind each eye. Immature rockhoppers have a line of cream feathers above eye and replacing plumes behind eye. Bare parts include: a red iris; bill, pink to orange-red; feet dull pink with darker webs and black soles.
Reproduction
Penguins are gregarious, and Rockhopper penguins breed in large colonies that may be composed of over a hundred thousand nests.
Mating calls, which are species specific, are called ecstatic vocalization. This draws attention to the bird and announces its intentions. Penguins mate with the same partners from previous years. Pairs usually return to the same nest on consecutive years.
Rockhopper penguins typically mate in the early spring or late summer, enabling the young to go to the sea in the mid-summer. Eggs are laid in November, clutch size is generally two eggs of unequal size, with only the chick from the larger egg usually surviving to maturity. The first egg is usually 20-50% smaller than second one. The small egg is usually lost, although it is capable of maturing into a normal bird. Sometimes pairs "adopt" a third egg; however, adopted eggs are also typically lost.
Incubation takes around 33 days and both parents will take it in turns sitting on the eggs for extended periods of a time whilst their partner forages for food. Penguins have a bare patch of skin on the lower abdomen (known as a 'brood pouch') that allows greater heat transfer to the eggs. Once the chicks have hatched, the male will remain to brood them for the first 25 days. He is nourished by the female who brings food back to the nest, or else he fasts for the entire period. If the female does not return with food for the chick once it has hatched, the male produces "penguin's milk" from his digestive system and regurgitates it for the baby.
After this time, the chicks are able to leave the nest and are left in small groups known as 'creches' whilst their parents forage.
Lifespan/Longevity
The average lifespan of a Rockhopper penguin is ten years.
Biology
Penguins have a waterproof coat that is maintained by constant grooming; this helps to flatten the feathers and to spread a waxy substance that is secreted just below the tail. Grooming is also an important social bond between pairs. Once a year however, the coat must be replaced; this annual molt takes around 25 days and occurs roughly a month after the completion of breeding. Prior to this imposed fasting period, adults spend time at sea building up fat reserves. After molting, the winter months are spent at sea before returning to shore to breed the following spring. The diet of the Rockhopper penguin is composed of a variety of oceanic species such as crustaceans, squid, octopus and fish. Groups may often feed together and dives may be to depths of up to 100 meters.
Behavior
Penguins are very sociable animals. It is very rare to see one alone. Rockhopper penguins are the most aggressive, as well as the most numerous of penguin species. They hide their heads under their wing while they rest. Rockhopper penguins leave the breeding colony in late summer or fall and spend three to five months at sea, where they find food.
Their loud cry or ecstatic vocalization, is used to announce their presence, attract a mate, or announce the boundaries of their territory. As well as vocalizing, these birds shake their heads and cause their yellow eyebrows to fly into a "halo" in order to attract a mate.
Distribution
Rockhopper penguins breed on a number of Southern Ocean islands. Three subspecies are recognized. The Southern Rockhopper (Eudyptes chrysocome chrysocome) is found in the Falkland Islands, Isla Pinguino, Staten Island and islands off southern Chile and Argentina. The Northern Rockhopper (E. c. moseleyi) breeds on Tristan da Cunha, Amsterdam and St Paul Islands. The third subspecies, Eastern Rockhopper (E. c. fiholi), is found on a variety of islands ranging from below the coast of South Africa to that of New Zealand.
Habitat
Rockhopper penguins are found in high grasses called tussocks, where they make burrows and nest. As their name implies, they live on rocky shorelines. Nesting occurs on cliffs and rocky gullies, usually situated near to freshwater, either natural springs or puddles.
Food Habits
Rockhopper penguins eat primarily krill (Euphausiacea). They also eat squid and other crustaceans. They make daily trips to the sea to forage.
Conservation Status
Many islands that house breeding colonies have been designated as reserves and the populations in the Falklands, Tristan da Cunha, Marion, Amesterdam, Island and Campbell are regularly monitored and studied. Greater investigation of population demographics and of potential threats is required. Following the starvation of over 100,000 Rockhopper penguins in the Falkland Islands, the Spheniscus Penguin Conservation Work Group published a report recommending that commercial fishing be excluded within 30 miles of penguin breeding sites. These measures have been adopted around southern Chile and Argentina, and these sites are healthy and increasing as a result. The adjacent Falklands have refused to introduce such protection, and populations continue to decline. Classified as Vulnerable (VU - A1bce+2bce) on the IUCN Red List 2002.
It is estimated that Rockhopper penguins have undergone a decline of more than 30% in their total population size over the past 30 years. For this reason, they are classified as vulnerable by the IUCN. If the decline continues, they may be up-listed to endangered in the near future. Threats to Rockhopper penguin populations include commercial fishing, which reduces the amount of available prey, and oil spills.
Threats
Some Rockhopper nesting colonies have recently shown dramatic falls in population numbers. The Falkland Islands once housed the stronghold for southern Rockhopper penguins, but over the last 20 years, numbers have declined by 90%. The reasons for these declines range from increasing disturbance and pollution, to declining fish stocks as a result of over fishing, and failure to provide no-fishing zones around penguin colonies. In some areas, such as Nightingale Island, the collection of eggs continues to affect the population whilst around Tristan da Cunha, driftnet fishing practices have caused significant mortality in the population of Rockhopper penguins.
Economic Importance for Humans
Penguins are a tourist attraction, and they are one of the main reasons people travel to the Falkland Islands and other habitats of these penguins.
References
- Eudyptes chrysocome (J. R. Forster, 1781) Encyclopedia of Life (accessed March 25, 2009)
- Species 2000 & ITIS Catalogue of Life: 2009 Annual Checklist. Bisby FA, Roskov YR, Orrell TM, Nicolson D, Paglinawan LE, Bailly N, Kirk PM, Bourgoin T, Baillargeon G., eds (2009), Species 2000: Reading, UK.
- Eudyptes chrysocomePhelan, D. 1999. The Animal Diversity Web (online).(accessed March 25, 2009)
- Rockhopper Penguins International Penguin Conservation Work Group (accessed March 25, 2009)
- New Zealand Penguins (accessed March 25, 2009)
- Southern Rockhopper Penguin BirdLife International] (accessed March 25, 2009)
- Northern Rockhopper Penguin BirdLife International] (accessed March 25, 2009)
- WoRMS, World Registry of Marine Species (accessed March 25, 2009)
- IUCN Red List (accessed March 25, 2009)
- Global Register of Migratory Species (accessed March 25, 2009)
