The macaroni penguin (Eudyptes chrysolophus) is a type of penguin found in areas from the Subantarctic to the Antarctic Peninsula. It is one of eight crested penguin species and is closely related to the royal penguin. Some scientists believe the two species might be the same. The macaroni penguin has a bright yellow crest on its forehead. Its face and upper body are black, and these areas are clearly separated from its white belly. Adult macaroni penguins weigh about 5.5 kg (12 lb) and are 70 cm (28 in) long. Males and females look similar, but males are slightly larger and stronger with bigger beaks. Like all penguins, they cannot fly. Their bodies are streamlined, and their wings are stiff and flat, forming flippers that help them swim underwater.
Macaroni penguins eat many types of crustaceans, especially krill, as well as small fish and squid. They consume more marine life each year than any other seabird. These penguins molt once a year, spending about three to four weeks on land before returning to the ocean. Their breeding groups can include up to 100,000 individuals, making them some of the largest and most crowded penguin colonies. After breeding in the summer, they spend six months at sea. A 2009 study found that macaroni penguins from Kerguelen traveled more than 10,000 km (6,200 mi) in the central Indian Ocean during this time.
With about 18 million individuals, the macaroni penguin is the most common penguin species. However, their numbers have decreased since the mid-1970s, and they are now classified as vulnerable.
Taxonomy
The macaroni penguin was first described in the Falkland Islands in 1837 by German naturalist Johann Friedrich von Brandt. It is one of eight species in the genus Eudyptes, which are also called crested penguins. The genus name comes from the Ancient Greek words eu, meaning "good," and dyptes, meaning "diver." The species name chrysolophus is from the Greek words chryse, meaning "golden," and lophos, meaning "crest."
The common name "macaroni penguin" was recorded in the Falkland Islands during the early 19th century. English sailors likely named the species because of its bright yellow crest, which resembled the style of a popular type of hat called a macaroni.
DNA evidence suggests the macaroni penguin split off from its closest relative, the royal penguin (Eudyptes schlegeli), about 1.5 million years ago. These two species are usually considered separate, but some scientists, such as Australian ornithologists Les Christidis and Walter Boles, have suggested the royal penguin might be a subspecies of the macaroni penguin. However, this idea is not accepted by major bird classification resources like the IOC World Bird List. The two species look similar, except the royal penguin has a white face instead of the black face found on the macaroni penguin.
Interbreeding between the macaroni penguin and the Indo-Pacific eastern rockhopper penguin (E. filholi) has been reported at Heard and Marion Islands. Three hybrids were recorded there during a 1987–88 Australian National Antarctic Research Expedition.
Description
The macaroni penguin is a large, crested penguin that looks similar to other penguins in the genus Eudyptes. An adult macaroni penguin is about 70 cm (28 in) long. Their weight changes depending on the season and whether they are male or female. Males weigh about 3.3 kg (7 lb) after incubating eggs or 3.7 kg (8 lb) after molting, up to 6.4 kg (14 lb) before molting. Females weigh about 3.2 kg (7 lb) after molting, up to 5.7 kg (13 lb) before molting. Typical measurements include a thick beak (from the opening of the mouth) that is 7 to 8 cm (2.8 to 3.1 in) long, with the upper part of the beak being about 1 cm shorter. The wing, from the shoulder to the tip, is about 20.4 cm (8.0 in) long, and the tail is 9–10 cm (3.5–3.9 in) long. The head, chin, throat, and upper body are black, clearly separated from the white underparts. The black feathers have a blue shine when new and turn brown with age. The most noticeable feature is the yellow crest that starts from the center of the forehead and extends backward to the back of the head. The flippers are blue-black on top with a white edge and mostly white underneath, with a black tip and leading edge. The large, round beak is orange-brown. The eyes are red, and there is a pink patch of bare skin from the base of the beak to the eye. The legs and feet are pink. Males and females look similar, but males are slightly larger. Males also have larger beaks, averaging 6.1 cm (2.4 in) compared to 5.4 cm (2.1 in) in females. This difference helps identify the sexes.
Young macaroni penguins are smaller, with smaller, duller-brown beaks, dark gray chins and throats, and no or only a few yellow feathers on their heads. Their crests fully develop when they are three to four years old, about one or two years before they begin breeding. Macaroni penguins molt once a year, replacing all their old feathers. Before molting, they spend about two weeks building up fat because they cannot eat during this time, as they cannot swim to find food without feathers. Molting takes three to four weeks, during which they stay on land. After molting, they return to the sea and go back to their colonies to mate in the spring. Survival rates are not well known. At South Georgia Island, between 49% and 78% of breeding adults returned successfully over three years, and about 10% of those that returned did not breed the following year.
Distribution and habitat
A 1993 study found that macaroni penguins are the most common species of penguin, with at least 11,841,600 pairs living worldwide. These penguins live from the Subantarctic region to the Antarctic Peninsula. At least 216 breeding groups have been recorded at 50 different locations. In South America, they are found in southern Chile, the Falkland Islands, South Georgia, the South Sandwich Islands, and the South Orkney Islands. They also live in 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, and the Heard and McDonald Islands. When searching for food, groups of macaroni penguins may travel north to islands near Australia, New Zealand, southern Brazil, Tristan da Cunha, and South Africa.
Ecology
The macaroni penguin eats many types of animals, including crustaceans, squid, and fish. The amounts of each food type depend on where the penguins live and the time of year. During the breeding season, over 90% of their food is Antarctic krill (Euphausia superba). Other foods, such as squid and small fish like marbled rockcod (Notothenia rossii), painted notie (Lepidonotothen larseni), Champsocephalus gunneri, and lanternfish species like Krefftichthys anderssoni, Protomyctophum tenisoni, and P. normani, become more important when the penguins are raising their chicks. Like some other penguin species, macaroni penguins sometimes swallow small stones (10–30 mm in size). Scientists think this behavior may help them dive deeper or break down food, especially the hard shells of crustaceans, which are a major part of their diet.
Macaroni penguins search for food daily from dawn to dusk when they have chicks to feed. They may also go on trips at night, especially as their chicks grow older. A 2008 study using implanted tracking devices found that foraging trips become longer after the chick-rearing period ends. During incubation and before molting, penguins leave their nests for 10–20 days. Macaroni penguins are the largest seabird group consuming marine resources, eating about 9.2 million tonnes of krill each year. Outside the breeding season, they dive deeper, longer, and more efficiently during winter migration than during summer breeding. Foraging dives usually happen during the day, but winter dives are limited by shorter daylight hours.
Macaroni penguins forage up to about 50 km (31 mi) from colonies at South Georgia and up to 59–303 km (37–188 mi) at Marion Island. They typically dive to depths of 15–70 m (49–230 ft), though they have been recorded diving as deep as 100 m (330 ft). Some night dives are shallower, reaching only 3–6 m (9.8–19.7 ft). Dives last no more than two minutes, and all dives are V-shaped, with no time spent on the ocean floor. About half of a foraging trip is spent diving. Each dive, penguins catch 4–16 krill or 40–50 amphipods.
Macaroni penguins are hunted by birds and aquatic mammals. Leopard seals (Hydrurga leptonyx), Antarctic fur seals (Arctocephalus gazella), Subantarctic fur seals (A. tropicalis), and killer whales (Orcinus orca) hunt adult penguins in the water. Predation on colonies is low if the penguins are undisturbed, as predators usually target unattended or abandoned eggs and chicks. Skuas, snowy sheathbills (Chionis alba), and kelp gulls (Larus dominicanus) eat eggs, while skuas and giant petrels also hunt chicks and injured or sick adult penguins.
Life history
Macaroni penguins are social animals that live in large groups when they nest and search for food. Their nesting areas are among the largest and most crowded. Scientist Charles Andre Bost studied macaroni penguins on Kerguelen and found that they spread out over an area larger than 3 million square kilometers. Twelve penguins with tracking devices traveled more than 10,000 kilometers during a six- to seven-month study. They stayed mostly in a region between 47–49°S and 70–110°E in the central Indian Ocean, where they did not come ashore. This area, called the Polar Frontal Zone, is known for having very few krill.
Living in groups leads to a lot of social interaction between penguins, which results in many visual and vocal behaviors. These behaviors are most active early in the breeding season and decrease when males are at sea. Some behaviors are used to challenge or avoid conflicts with others. For example, penguins on nearby nests may "bill-joust," locking their beaks and wrestling to push each other away. They may also use their flippers to strike or peck at the back of an opponent. Other behaviors, like the "slender walk," show submission. During this walk, penguins move with their feathers flat, flippers in front of their bodies, and heads and necks hunched. They may also hunch their heads and necks while sitting on eggs or at their nests.
Female macaroni penguins can begin breeding at about five years old, while males usually start at six or older. This happens because there are more males than females. Males begin showing off to attract mates a few days after females arrive. These displays include the "ecstatic display," where a penguin bows forward, makes loud noises, and then stands upright with its head and neck vertical. It then moves its head side to side while making loud sounds. Penguins also bow to each other, trumpet, and preen. Studies on penguins at South Georgia show that about three-quarters of pairs breed together again the next year.
Adult macaroni penguins usually start breeding in late October and lay their eggs in early November. Their nests are shallow pits in the ground, sometimes lined with pebbles, stones, or grass, or nestled in grass clumps on South Georgia Island. Nests are very close together, with spacing ranging from about 66 cm (26 in) in the middle of a colony to 86 cm (34 in) at the edges. Each breeding season, a pair lays two eggs. The first egg is smaller, weighing 90–94 g (3.2–3.3 oz), about 61–64% the size of the second egg, which weighs 145–155 g (5.1–5.5 oz). The first egg rarely survives. Together, the two eggs weigh 4.8% of the mother’s body weight. The egg has 20% yolk, 66% albumen, and 14% shell. The shell is thick to prevent breaking, and the yolk is large, which helps the chick develop quickly. Some yolk remains after hatching and is eaten by the chick in its first few days.
Studies on related penguin species suggest that females may remove the first egg when the larger second egg is laid. Both parents share the task of incubating the eggs, taking turns in three sessions of about 12 days each over five weeks. The first session is shared by both parents, then the male leaves to go to sea, leaving the female to care for the egg alone. When the male returns, the female goes to sea and stays away until the chick hatches. Both parents fast for long periods during breeding. The male fasts for 37 days after arriving, then returns to sea for 10 days before fasting again for 36 days while incubating the egg and young. The female fasts for 42 days from her arrival until late in the incubation period. Both lose 36–40% of their body weight during this time. The second egg hatches about 34 days after it is laid. Macaroni penguins usually leave their colonies by April or May to return to the ocean.
After the egg hatches, the male penguin cares for the chick for about 23 to 25 days. During this time, the male protects the chick and helps keep it warm, as the chick has few feathers. The female brings food to the chick every one to two days. When not protected by adults, chicks gather in groups called crèches to stay warm and safe. Once their adult feathers grow in at about 60 to 70 days, the chicks are ready to go to sea on their own.
Conservation
The macaroni penguin population is estimated to be about 18 million adult penguins. However, there has been a big decrease in numbers in some areas. For example, the population on South Georgia dropped by half between the mid-1970s and mid-1990s, and the species is no longer found on Isla Recalada in Southern Chile. Over the past 30 years, the overall population decline has led to the species being listed as Vulnerable by the IUCN Red List of Threatened Species. Scientists are monitoring penguin populations at many breeding sites, and several islands where they live are protected as reserves. The Heard Islands and McDonald Islands are World Heritage Sites that support macaroni penguins. The species may be affected by commercial fishing and ocean pollution. A 2008 study suggests that climate changes and fishing activities may have reduced krill numbers, which could harm the ability of female penguins to reproduce.