Macaroni penguin

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Macaroni penguin
SGI-2016-South Georgia (Cooper Bay)–Macaroni penguin (Eudyptes chrysolophus) 01.jpg
In
South Georgia
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Sphenisciformes
Family: Spheniscidae
Genus: Eudyptes
Species:
E. chrysolophus
Binomial name
Eudyptes chrysolophus
(Brandt, 1837)
Macaroni penguin range
Breeding colonies in red
Synonyms

Catarractes chrysolophus Brandt, 1837[2]
Eudyptes saltator (Stephens, 1826)

The macaroni penguin (Eudyptes chrysolophus) is a species of penguin found from the Subantarctic to the Antarctic Peninsula. One of six species of crested penguin, it is very closely related to the royal penguin, and some authorities consider the two to be a single species. It bears a distinctive yellow crest that resembles macaroni, from which its name is derived. Its face and upperparts are black and sharply delineated from the white underparts. Adults weigh on average 5.5 kg (12 lb) and are 70 cm (28 in) in length. The male and female are similar in appearance; the male is slightly larger and stronger with a relatively larger bill. Like all penguins, it is flightless, with a streamlined body and wings stiffened and flattened into flippers for a marine lifestyle.

Its diet consists of a variety of

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. After spending the summer breeding, penguins disperse into the oceans for six months; a 2009 study found that macaroni penguins from Kerguelen travelled over 10,000 km (6,200 mi) in the central Indian Ocean. With about 18 million individuals, the macaroni penguin is the most numerous penguin species. Widespread declines in populations have been recorded since the mid-1970s and their conservation status is classified as vulnerable
.

Taxonomy

The macaroni penguin was described from the Falkland Islands in 1837 by German naturalist Johann Friedrich von Brandt.[3] It is one of six or so species in the genus Eudyptes, collectively known as crested penguins. The genus name is derived from the Ancient Greek words eu "good", and dyptes "diver". The specific name chrysolophus is derived from the Greek words chryse "golden", and lophos "crest".[4]

The common name was recorded from the early 19th century in the Falkland Islands. English sailors apparently named the species for its conspicuous yellow crest.[5] It is similar to the then fashionable Macaroni.

Les Christidis and Walter Boles, to treat the royal penguin as a subspecies of the macaroni penguin.[7][8] The two species are very similar in appearance; the royal penguin has a white face instead of the usually black face of the macaroni penguin.[9] Interbreeding with the Indo-Pacific subspecies of the southern rockhopper penguin (E. chrysocome filholi) has been reported at Heard and Marion Islands, with three hybrid subspecies recorded there by a 1987–88 Australian National Antarctic Research Expedition.[10]

Description

A skeleton on display in Manchester Museum
Showing the conspicuous orange and yellow crests

The macaroni penguin is a large, crested penguin, similar in appearance to other members of the genus Eudyptes. An adult bird has an average length of around 70 cm (28 in);

culmen being around a centimetre less. The wing, from the shoulder to the tip, is around 20.4 cm (8.0 in) and the tail is 9–10 cm (3.5–3.9 in) long.[12] The head, chin, throat, and upper parts are black and sharply demarcated against the white under parts. The black plumage has a bluish sheen when new and brownish when old. The most striking feature is the yellow crest that arises from a patch on the centre 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. The iris is red and a patch of pinkish bare skin is found from the base of the bill to the eye. The legs and feet are pink. The male and female are similar in appearance; males tend to be slightly larger.[3] Males also bear relatively larger bills, which average around 6.1 cm (2.4 in) compared to 5.4 cm (2.1 in) in females; this feature has been used to tell the sexes apart.[11]

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 three to four years, a year or two before breeding age.[3]

Macaroni penguins

moult once a year, a process in which they replace all of their old feathers. They spend around two weeks accumulating fat before moulting because they do not feed during the moult, as they cannot enter the water to forage for food without feathers. The process typically takes three to four weeks, which they spend sitting ashore. Once finished, they go back to sea and return to their colonies to mate in the spring.[13] Overall survival rates are poorly known; the successful return of breeding adults at South Georgia Island varied between 49% and 78% over three years, and around 10% of those that did return did not breed the following year.[14]

Distribution and habitat

A colony climbing in Cooper Bay, South Georgia

A 1993 review estimated that the macaroni was the most abundant species of penguin, with a minimum of 11,841,600 pairs worldwide.[15] Macaroni penguins range from the Subantarctic to the Antarctic Peninsula; at least 216 breeding colonies at 50 sites have been recorded.[16] 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, and the Heard and McDonald Islands.[17] While foraging for food, groups will range north to the islands off Australia, New Zealand, southern Brazil, Tristan da Cunha, and South Africa.[18]

Ecology

Feeding

The diet of the macaroni penguin consists of a variety of

exoskeletons of crustaceans which are a significant part of its diet.[22][23]

Foraging for food is generally conducted on a daily basis, from dawn to dusk when they have chicks to feed. Overnight trips are sometimes made, especially as the chicks grow older;[19] a 2008 study that used surgically implanted data loggers to track the movement of the birds showed the foraging trips become longer once the chick-rearing period is over.[24] Birds venture out for 10–20 days during incubation and before the moult.[19] Macaroni penguins are known to be the largest single consumer of marine resources among all of the seabirds, with an estimated take of 9.2 million tonnes of krill a year.[25] Outside the breeding season, macaroni penguins tend to dive deeper, longer, and more efficiently during their winter migration than during the summer breeding season. Year round, foraging dives usually occur during daylight hours, but winter dives are more constrained by daylight due to the shorter days.[26]

Foraging distance from colonies has been measured at around 50 km (31 mi) at South Georgia,

amphipods per dive.[19]

Predators

The macaroni penguin's

killer whale (Orcinus orca) hunt adult macaroni penguins in the water. Macaroni colonies suffer comparatively low rates of predation if undisturbed; predators generally only take eggs and chicks that have been left unattended or abandoned. Skua species, the snowy sheathbill (Chionis alba), and kelp gull (Larus dominicanus) prey on eggs, and skuas and giant petrels also take chicks and sick or injured adult birds.[14]

Life history

A nesting pair at the Hannah Point, Livingston Island

Like most other penguin species, the macaroni penguin is a

geolocation sensors, the 12 penguins studied travelled over 10,000 km (6,200 mi) during the six- to seven-month study period and spent their time largely within a zone 47–49°S and 70–110°E in the central Indian Ocean, not coming ashore once. This area, known as the Polar Frontal Zone, was notable for the absence of krill.[30]

An individual porpoising in Cooper Bay

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.[31] These behaviours peak early in the breeding period, and colonies particularly quieten when the male macaroni penguins are at sea.[32] Agonistic displays are those which are intended to confront or drive off or, alternatively, appease and avoid conflict with other individuals.[31] 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 its opponent's nape.[33] 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.[34]

Courtship and breeding

An egg from the Kerguelen Islands

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.[citation needed] Commencing a few days after females arrive at 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.[33] In the 'ecstatic display', a penguin bows forward, making loud throbbing sounds, and then extends its head and neck up until its neck and beak are vertical. The bird then waves its head from side to side, braying loudly.[35] Birds also engage in mutual bowing, trumpeting, and preening.[33] Monitoring of pair fidelity at South Georgia has shown around three-quarters of pairs will breed together again the following year.[14]

Adult macaroni penguins typically begin to breed late in October, and lay their

tussock grass (on South Georgia Island).[36] Nests are densely packed, ranging from around 66 cm (26 in) apart in the middle of a colony to 86 cm (34 in) at the edges.[36] A fertile macaroni penguin will lay two eggs each breeding season. The first egg to be laid weighs 90–94 g (3.2–3.3 oz), 61–64% the size of the 145–155 g (5.1–5.5 oz) second, and is extremely unlikely to survive.[36] The two eggs together weigh 4.8% of the mother's body weight; the composition of an egg is 20% yolk, 66% albumen, and 14% shell.[37] Like those of other penguin species, the shell is relatively thick to minimise risk of breakage, and the yolk is large, which is associated with chicks born in an advanced stage of development.[38] Some of the yolk remains at hatching and is consumed by the chick in its first few days.[38]

A preserved chick at the Auckland Museum

The fate of the first egg is mostly unknown, but studies on the related

incubating the egg is divided into three roughly equal sessions of around 12 days each over a five-week period.[36] The first session 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.[citation needed] Both sexes fast for a considerable period during breeding; the male fasts for 37 days after arrival until he returns to sea for around 10 days before fasting while incubating eggs and young for another 36 days, and the female fasts for 42 days from her arrival after the male until late in the incubation period.[39] Both adults lose 36–40% of their body weight during this period.[40] The second egg hatches around 34 days after it is laid. Macaroni penguins typically leave their breeding colony by April or May to disperse into the ocean.[18][41]

From the moment the egg is hatched, the male macaroni penguin cares for the newly hatched chick. For about 23 to 25 days, the male protects its offspring and helps to keep it warm, since only a few of its feathers have grown in by this time. The female brings food to the chick every one to two days. When they are not being protected by the adult male penguins, the chicks form crèches to keep warm and stay protected. Once their adult feathers have grown in at about 60 to 70 days, they are ready to go out to sea on their own.[42]

Conservation

The population of macaroni penguins is estimated at around 18 million mature individuals; a substantial decline has been recorded in several locations.

World Heritage Sites for the macaroni penguin.[43] The macaroni penguin may be being impacted by commercial fishing and marine pollution.[46] A 2008 study suggests the abilities of female penguins to reproduce may be negatively affected by climate- and fishing-induced reductions in krill density.[47]

References

  1. . Retrieved 12 November 2021.
  2. ^ "Species Eudyptes chrysolophus (Brandt, 1837)". Australian Biological Resources Study: Australian Faunal Directory. Canberra, ACT: Department of the Environment, Water, Heritage and the Arts, Commonwealth of Australia. 9 October 2008. Archived from the original on 6 November 2012. Retrieved 25 March 2010.
  3. ^ a b c d Williams (1995) p. 211
  4. .
  5. .
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  8. ^ Juliff, Peter (December 2008). "From the Pole to the Equator: A panoply of Penguins" (PDF). The Bird Observer (857). Bird Observation & Conservation Australia. Archived from the original (PDF) on 2011-07-06. Retrieved 2009-01-27.
  9. ^ Williams (1995) p. 214
  10. .
  11. ^ a b Williams (1995) p. 213
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  14. ^ a b c Williams (1995) p. 219
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  17. ^ Bernstein, Neil; Tirrell, Paul. "Short Communications: New Southerly Record for the Macaroni Penguin (Eudyptes chrysolophus) on the Antarctic Peninsula" (PDF). Auk. Retrieved 2008-12-07.
  18. ^ a b c Curry, Tiera. "Macaroni Penguin". Center for Biological Diversity website. Center for Biological Diversity. Retrieved 2008-11-17.
  19. ^ a b c d Williams (1995) p. 215
  20. ^ Williams (1995) pp. 215–16
  21. ^ Splettstoesser J, Todd FS (1999). "Stomach stones from Emperor Penguin Aptenodytes forsteri colonies in the Weddell Sea" (PDF). Marine Ornithology. 27: 97–100.
  22. .
  23. ^ De Villiers MS, Bruyn PJ (2004). "Stone-swallowing by three species of penguins at sub-antarctic Marion Island" (PDF). Marine Ornithology. 32 (2): 185–86. Retrieved 2012-08-20.
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  28. ^ Brown CR (1987). "Travelling speed and foraging range of macaroni and rockhopper penguins at Marion Island" (PDF). Journal of Field Ornithology. 58: 118–25. Retrieved 2012-08-20.
  29. ^ Green K, Williams R, Green MG (1998). "Foraging ecology and diving behavior of Macaroni Penguins Eudyptes chrysolophus at Heard Island" (PDF). Marine Ornithology. 26: 27–34.
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  31. ^ a b Williams (1995) p. 57
  32. ^ Williams (1995) p. 61
  33. ^ a b c Williams (1995) p. 216
  34. ^ Williams (1995) p. 190
  35. ^ Williams (1995) p. 191
  36. ^ a b c d Williams (1995) p. 217
  37. ^ Williams (1995) p. 218
  38. ^ a b Williams (1995) p. 24
  39. ^ Williams (1995) p. 112
  40. ^ Williams (1995) p. 113
  41. ^ Commonwealth of Australia (2005). "Macaroni Penguins". Heard Island and McDonald Islands. Australian Government Department of the Environment, Water, Heritage, and the Arts. Archived from the original on October 18, 2010. Retrieved 2008-11-04.
  42. ^ Reynolds, Katie (2001). "Eudypteschrysolophus". Animal Diversity Web. Retrieved 2008-11-11.
  43. ^ a b c Benstead, Phil; David Capper; Jonathan Ekstrom; Rachel McClellan; Alison Stattersfield; Andy Symes (2008). "Species Factsheet". BirdLife International. BirdLife International. Retrieved 2009-01-16.
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  46. ^ Ellis S, Croxall JP, Cooper J (1998). Penguin Conservation Assessment and Management Plan. Apple Valley, Minnesota: IUCN/SSC Conservation Breeding Specialist Group.
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Cited texts

External links