The Macaroni Penguin (Eudyptes chrysolophus) is a species of penguin found from the Subantarctic to the Antarctic Peninsula. It is one of six species of crested penguin, and bears a distinctive yellow crest. An adult averages about 5.5 kg (12 lb) in weight and 70 cm (28 in) in length. The male and female are similar in the otherwise black and white plumage, although the former is slightly larger with a larger bill. Like all penguins, it is flightless, with a streamlined body and wings stiffened and flattened into flippers for a marine lifestyle.

Their diet consists of a variety of crustaceans, mainly krill, as well as small fish and cephalopods. They moult once a year, spending about three to four weeks ashore, before returning to the sea. Numbering up to 100,000 individuals, the breeding colonies of the Macaroni Penguin are among the largest and densest of all penguin species. There are about 18 million Macaroni Penguins, and the number is decreasing, due to unideal environmental conditions and their many predators. These factors result in their vulnerable conservation status.

Taxonomy

The Macaroni Penguin was described from the Falkland Islands in 1837 by German naturalist Johann Friedrich von Brandt. It is a member of the genus Eudyptes, which is derived from the Ancient Greek words eu "good", and dyptes "diver". The species epithet chrysolophus is derived from the Greek words chryse "golden", and lophos "crest". There are six species in the genus, collectively known as crested penguins.

The common name was given to the species by English explorers, probably due to the bird's conspicuous yellow crest. Maccaronism was a term for a particular style in 18th-century England marked by flamboyant or excessive ornamentation. A person who adopted this fashion was labeled a maccaroni or macaroni, as in the song Yankee Doodle.

Mitochondrial and nuclear DNA evidence suggests that the Macaroni Penguin split from its closest relative, the Royal Penguin (Eudyptes schlegeli), around 1.5 million years ago. Although Macaroni Penguins and Royal Penguins have always been considered separate species, the close similarities of their DNA sequences has recently led some, such as the Australians Les Christidis and Walter Boles, to reclassify the Royal as a subspecies of the Macaroni. The two species are very similar in appearance, but Royal Penguins have white faces instead of the usually black faces of the Macaronis.

Description Macaroni Penguins are known for their conspicuous orange and yellow crests.

The Macaroni Penguin is a large, crested penguin, similar in appearance to other members of the genus Eudyptes, such as the similar but larger Royal Penguin. The adult Macaroni Penguin has an average length of around 71 cm (28 in); the weight varies markedly depending on time of year and sex. Males may average from 3.3 kg (7 lb) after incubating, or 3.7 kg (8 lb) post-molt, to 6.4 kg (14 lb) pre-molt, while females may average 3.2 kg (7 lb) post-molt, to 5.7 kg (13 lb) pre-molt. The head, chin, throat and upperparts are black, and sharply markated against the white underparts. The black plumage has a bluish sheen when new and brownish when old. The most stiking feature is the yellow crest that arises from a patch on the center of the forehead, and extends horizontally backwards to the nape. The flippers are blue-black on the upper surface with a white trailing edge, and mainly white underneath with a black tip and leading edge. The large bulbous bill is orange-brown and the iris is red. There is a patch of pinkish bare skin from the base of the bill to the eye. The legs and feet are pink. The male and female are similar in appearance, although the former tend to be slightly larger. The former also bear larger bills, which average around 6.1 cm (2.4 in), opposed to 5.4 cm (2.1 in) in females; this has been used to tell the sexes apart.

Immature birds are distinguished by their smaller size, smaller duller brown bill, dark grey chin and throat, and absent or underdeveloped head plumes, often just a scattering of yellow feathers. The crest is fully developed in birds aged 3-4 years, a year or two before breeding age.

Macaroni Penguins moult once a year, a process in which they replace all of their old feathers. Before moulting, they spend around two weeks fattening themselves up because moulting requires much energy. During moulting, they do not feed because without feathers they cannot go in the water to forage for food. The process typically takes from three to four weeks, which they spend sitting ashore. Once they are finished moulting, they go back to sea. In the spring they return to their colonies to mate.

Vocalization

The calls of this species are similar to other crested penguins; birds are especially noisy in colonies when establishing territories and forming pairs, and quieten down during incubation. During this pariod, parents make trumpeting calls when changing over shifts at the nest; birds recognise each other more by voice than by location. Calls recorded at colonies on South Georgia have a more rapid rhythm and lower pitch than those on Kerguelen and Crozet Islands.

Distribution and habitat

A 1993 review estimated that there are a minimum of 11,841,600 pairs of Macaroni Penguins worldwide. Macaroni Penguins range from the sub-Antarctic to the Antarctic Peninsula. There are a minimum of 216 breeding colonies at 50 sites. In South America, Macaroni Penguins are found in southern Chile, the Falkland Islands, South Georgia and the South Sandwich Islands, and South Orkney Islands. They also occupy much of Antarctica and the Antarctic Peninsula, including the northern South Shetland Islands, Bouvet Island, the Prince Edward and Marion islands, the Crozet Islands, the Kerguelen Islands, the Heard and McDonald Islands.

While foraging for food, groups will range north to the islands off Australia, New Zealand, southern Brazil, Tristan da Cunha, and South Africa.

Behavior

Like other penguin species, The Macaroni Penguin is a social animal in its nesting and its foraging behavior; its breeding colonies are among the largest and most densely populated of all penguin species. Outside the breeding season, the Macaroni penguin is pelagic; birds disperse into the sea from April or May until October.

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. These behaviours peak early in the breeding period, and colonies particularly quieten when the male Macaroni Penguins are off at sea. Agonistic displays are those which are intended to confront or drive off, or alternately appease and avoid conflict with, other individuals. Macaroni penguins, particularly those on adjacent nests, may engage in bill-jousting; birds lock bills and wrestle, each trying to unseat the other, as well as batter with flippers and peck or strike their opponent's nape. Submissive displays include the slender walk, where birds move through the colony with feathers flattened, flippers moved to the front of the body, and head and neck hunched, and general hunching of head and neck when incubating or standing at the nest.

Diet A macaroni penguin swimming at Twycross Zoo.

The diet of the Macaroni Penguin consists of a variety of crustaceans, squid and fish, although the proportions that each make up vary with locality and season. Krill, particularly Antarctic krill (Euphausia superba), account for over 90% of food during breeding season. Cephalopods and small fish such as the Marbled rockcod (Notothenia rossii), Painted notie (Lepidonotothen larseni), Champsocephalus gunneri, the lanternfish species Krefftichthys anderssoni, Protomyctophum tenisoni and P. normani become more important during chick-rearing. Foraging for food is generally conducted on a daily basis, from dawn (0500-0700) to dusk, when there are chicks to feed. Overnight trips are sometimes made, especially as the chicks grow older. In contrast, birds venture out for 10-20 days during incubation, and before the molt. The habits of Macaroni Penguins outside the breeding season are unknown.

Foraging distance from colonies has been measured at around 50 km (31 mi) at South Georgia, offshore over the continental shelf, and anywhere from 59 to 303 kilometres (37 to 188 mi) at Marion Island. Macaroni Penguins normally forage at depths of 15 to 70 metres (49 to 230 ft), but have been recorded diving down to 100 metres (330 ft) on occasions. Some night foraging does occur, but these dives are much shallower, ranging from only 3 to 6 metres (9.8 to 20 ft) in depth. Dives rarely exceed two minutes in duration. All dives are 'V'-shaped, that is no time is spent at the bottom, and around half the time on a foraging trip is spent diving. Birds have been calculated as catching anywhere from 4-16 krill, or 40-50 amphipods per dive.

Predators

The Macaroni Penguin's predators consist of birds and aquatic mammals. The Leopard Seal (Hydrurga leptonyx), Antarctic Fur Seal (Arctocephalus gazella) and Subantarctic Fur Seal (A. tropicalis) sometimes hunt adult Macaroni Penguins in the water. Colonies suffer low rates of predation if undisturbed; predators generally only taking eggs and young that have been left unattended or deserted. Skua species, the Snowy Sheathbill (Chionis alba), and Kelp Gull (Larus dominicanus) prey on eggs, and skuas and Giant Petrels also sometimes take chicks.

Courtship and breeding

Female Macaroni Penguins can begin breeding at around five years of age, while the males do not normally breed until at least six years old. Females breed at a younger age because the male population is larger. The surplus of male penguins allows the female penguins to select more experienced male partners as soon as the females are physically able to breed. Commencing a few days after females arrive to the colony, sexual displays are used by males to attract partners and advertise their territory, and by pairs once together at the nest site and at changeover of incubation shifts. In the ecstatic display, a penguin bows forward, making loud throbbing sounds, and then extends its head and neck up until the neck and beak are vertical. The bird then waves its head from side to side braying loudly. Birds also engage in mutual bowing, trumpeting, and preening.

Adult Macaroni Penguins typically begin to breed late in October, and lay their eggs in early November. The nest itself is a shallow scrape in the ground which may be lined with some pebbles, stones, or grass, or nestled in a clump of tussock grass (on South Georgia Island). Nests are densely packed, ranging from around 66 cm apart in the middle of a colony to 86 cm at the edges. A fertile Macaroni Penguin will lay two eggs each breeding season. The first egg to be laid weighs 90"?94 grams (3.2"?3.3 oz), 61"?64% the size of the 145"?155-gram (5.1"?5.5 oz) second, and is extremely unlikely to survive. Its fate is mostly unknown, but studies on the related Royal Penguin and Erect-crested Penguin show the female tips the egg out, when the larger second egg is laid. The task of incubating the egg is divided into three roughly equal sessions of around 12 days each over a five week period. The first is shared by both parents, followed by the male returning to sea, leaving the female alone to tend the egg. Upon the male's return, the female goes off to sea and does not return until the chick has hatched. The second egg hatches around 34 days after it is laid. Macaroni Penguins typically leave their breeding colony by April or May.

From the moment the egg is hatched, the male Macaroni Penguin cares for the newly hatched chick. For about three weeks, or twenty-three to twenty-five days, the male protects its offspring and helps to keep it warm, since only a few of its feathers have grown in at this point. The female brings food to the chick every one to two days. At this early stage, chicks have not grown their adult feathers. When they are not being protected by the adult male penguins, the chicks form groups with each other called creches. They do this in order to keep warm and stay protected. Once their adult feathers have grown in, at about 60"?70 days, they are ready to go out to sea on their own.

Conservation

Although the number of Macaroni Penguins is currently high, the decline of the overall population in the last 30 years has resulted in the classification of the species as globally Vulnerable by the IUCN Red List of Threatened Species. Long-term monitoring programs are underway at a number of breeding colonies, and many of the islands that support breeding populations of this penguin are protected reserves. The Heard Islands and McDonald Islands are World Heritage Sites for the Macaroni Penguin. If the threats facing the Macaroni Penguin continue unabated, it seems likely that the population decline will continue.

Cited text

• Williams, Tony D. (1995). The penguins: Spheniscidae. Oxford, England: Oxford University Press. ISBN 0-19-854667-X.