Eastern rockhopper penguin

The eastern rockhopper penguin (Eudyptes chrysocome filholi) is a crested penguin with yellow crest feathers.[1] It is a subspecies of the southern rockhopper penguin (Eudyptes chrysocome) found in subantarctic regions and the Indian Ocean.[1] It is one of the smallest crested penguins and has distinctive pink margins around its bill.[2]

Eastern rockhopper penguin
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Sphenisciformes
Family: Spheniscidae
Genus: Eudyptes
Species:
E. chrysocome
Subspecies:
E. c. filholi
Trinomial name
Eudyptes chrysocome filholi
Hutton, 1878
Synonyms

Eudyptes filholi

Description

The eastern rockhopper penguin is a small, crested penguin with a black back and throat, a white belly and pink feet.[1] This seabird measures approximately 45–55 cm in length, and weighs 2.2–4.3 kg.[3] It has a thin yellow stripe that stretches from its lower forehead, over its red eye and splits into crest feathers at the back of its head.[2] The crest feathers are composed of long, thin, spiky yellow feathers on either side of the penguin’s head and they are joined by shorter black feathers.[2] Rockhopper penguins have an orange-brown bill and the eastern rockhopper penguin has distinctive pink margins around the bill.[1] Males and females differ in body size and size of their bill;[1] males are generally larger and have a thicker bill.[2]

Fledglings, which are around 65 days old, are bluish black all over and lack crest feathers.[1] They also have a smaller, thinner bill than juveniles and adults.[1] Juveniles, which are penguins aged 1 to 2 years old, are a black-brown color with a grey throat.[1] They develop a brown-orange bill that is darker than the adult coloring and have small yellow crest feathers.[1] Eastern rockhopper penguins moult and get their adult plumage at 2 years old.[1]

Taxonomy

The rockhopper penguin can be divided into two species; the northern rockhopper penguin (Eudyptes moseleyiI) and the southern rockhopper penguin.[2] These populations differ in many ways including morphological, ecological and behavioural differences.[2] The northern rockhopper penguin is larger than its southern counterpart and has longer crest feathers.[4] Other morphological differences include different color patterns on the underside of their flipper and different size eyestripes.[4] They also exhibit different behavioural traits such as foraging in different water temperatures.[2] Two subspecies of the southern rockhopper penguin are recognized; the eastern and the western rockhopper penguin (Eudyptes chrysocome chrysocome).[2] These subspecies differ mainly in their distribution; the western species is found in Cape Horn, South America and the Falkland Islands while its eastern counterpart occupies the Southern Indian and Pacific Ocean.[2] The eastern rockhopper penguin can also be distinguished by its pink margins around the bill.[2]

Habitat and Distribution

The eastern rockhopper penguin is found in the southern Indian and Pacific ocean from Prince Edward Islands to the Antipodes Islands.[2] Rockhopper penguins, in general, occupied a circumpolar distribution in the arctic during breeding season.[1] Eastern rockhopper penguins breed in the Marion Islands, Macquarie island and subantarctic islands in New Zealand such as the Antipodes islands and Campbell island.[4] These penguins occupy a mainly marine pelagic habitat and only return to land to breed and moult.[1] They spend the winter months, approximately April to October, in the southern Indian Ocean foraging for food and can spend up to 6 months at sea.[1] They travel, on average, 2000 to 4000 km away from their breeding site during this winter period.[1] This species mainly forages in cool waters; ocean temperatures of less than 4.5 degrees Celsius.[5]

Eastern rockhopper penguins are surface nesters and will build their nest on slopes or rocky shores near the coastline.[2] Colonies will usually form on steep cliffs near the sea and can contain tens-of-thousands of nests.[1] Their nests are made of small pebbles and can occasionally contain some vegetation.[1] Some colonies have settled within grasslands such as tussock, however the soil often erodes down to rock with the accumulation of guano and trampling over a few decades.[1] Eastern rockhopper penguins are rarely found more than 200 meters away from the coastline, since it is ideal to remain near their food supply.[1]

Behavior

Vocalization

Eastern rockhopper penguins use calls for parent-chick recognition when returning to the colony with food.[6] They also use a song for courtship that can be described as a short repeated rhythmic ascending song.[2][7] The song of an adult rockhopper penguin can have 5-30 syllables with the first syllable the longest.[6] Their contact call used by chicks and adults is a very short shrill bark.[2]

Diet and foraging

Eastern rockhopper penguins feed on a variety of fish, crustaceans and cephalopods such as krill and squid.[8] Their diet can differ depending on where they are in their life cycle.[5] During their pre-moult season, eastern rockhopper penguins mainly consume crustaceans, while during the breeding period their diet heavily relies on euphausiids in the Marion islands.[5] Different breeding location will also impact their diet; chicks in the Campbell island were found to mainly consume dwarf cod.[9] Rockhopper penguins highly depend on a predictable food source near their nesting habitat to feed their chicks.[10] However, if necessary rockhopper penguins can forage up to 120 km away from their breeding grounds to find food for their chicks.[8]

They are diurnal divers; the majority of their foraging activity occurs during the day with the deepest dives occurring at sunrise.[11] When searching for food, they usually stay at a depth of 6m and dive down 30-50m in the water column to catch their prey.[11] They tend to forage in cool waters since they are most productive.[5] They also selected foraging areas with large generation of eddies currents.[5] This type of current supports high aggregations of prey species.[5]

The predators of the rockhopper penguin includes fur seals and sea lions.[3] As well, brown skuas (Stercorarius antarcticus) and northern giant petrel (Macronectes halli) prey on rockhopper penguin eggs and chicks.[3]

Reproduction

Breeding season starts in October for eastern rockhopper penguins; males return to the breeding colony first and the females follow shortly after.[1] Courtship begins between pairs and both sexes fast until the female lays the first eggs usually around the beginning of November.[1] After the eggs are laid, the male and female will share all the parental duties.[1] The first incubation period is shared and both parents will fast during this time, approximately 7 days.[11] After this, the female takes the first solo incubation shift while the male goes to forage at sea, this can last up to 3 weeks.[11] Once the male returns, he takes over incubation while the female forages for approximately 10 days, by the time she returns, the chicks have hatched.[11] After the chicks hatch, the male will guard the chicks and continue to fast while the female forages and returns with food for the chicks.[3] The chicks form creches when they are around 24 days old and during this time both parents foraged and return with food.[1] A creche is a common occurrence in bird species when the juveniles form protective groups to allow the parents to forage.[12] Parent penguins continue to feed chicks until they fledge around February[13] when they are approximately 65 days old.[1] Adult penguins will return to the breeding colony in April to moult before their winter at sea.[3]

Threats and Conservation

The eastern rockhopper penguin is considered a vulnerable species due to rapid population declines.[13] This decrease in population is mostly seen in breeding regions since it is the easiest form of census.[3] Most research agrees that the decline in rockhopper penguins is due to low food availability and decrease in food quality driven by climate change.[1][3][13] Due to climate change, sea surface and ocean temperatures are changing and this effects the distribution of prey populations.[3] Rockhopper penguins, and many other species, are sensitive to changes in water temperature[13] and as a consequence, adult penguins must forage farther away from breeding colonies.[3] They often return with smaller amounts of food for their chicks which leads to a decrease in body mass.[3] Low food availability also has a large effect on penguin’s moult period.[3] Moulting is a very energy demanding process and requires penguins have sufficient body mass.[3] Due to poor diet, there is an increase in mortality during the moulting season.[3] Low food quality and abundance in wintering regions have also led to an increase in adult mortality.[3] Climate change has additionally affected the amount and intensity of storms in breeding ranges.[13] Intensity of winds displace prey populations and reduce penguin foraging success.[13]

References
  1. Morrison (2013). "Eastern rockhopper penguin | New Zealand Birds Online". New Zealand Birds Online: The digital Encyclopaedia of New Zealand Birds. Retrieved 3 October 2020.
  2. Martínez, Isabel; Christie, David; Jutglar, Francesc; Garcia, Ernest; Kirwan, Guy M. (2020-03-04). "Southern Rockhopper Penguin (Eudyptes chrysocome)". Birds of the World.
  3. Morrison, Kyle W.; Battley, Phil F.; Sagar, Paul M.; Thompson, David R. (February 2015). "Population dynamics of Eastern Rockhopper Penguins on Campbell Island in relation to sea surface temperature 1942–2012: current warming hiatus pauses a long-term decline". Polar Biology. 38 (2): 163–177. doi:10.1007/s00300-014-1575-x. ISSN 0722-4060.
  4. Banks, Jonathan; Van Buren, Amy; Cherel, Yves; Whitfield, James B. (December 2006). "Genetic evidence for three species of rockhopper penguins, Eudyptes chrysocome". Polar Biology. 30 (1): 61–67. doi:10.1007/s00300-006-0160-3. ISSN 0722-4060.
  5. Whitehead, T. O.; Kato, A.; Ropert-Coudert, Y.; Ryan, P. G. (January 2016). "Habitat use and diving behaviour of macaroni Eudyptes chrysolophus and eastern rockhopper E. chrysocome filholi penguins during the critical pre-moult period". Marine Biology. 163 (1): 19. doi:10.1007/s00227-015-2794-6. ISSN 0025-3162.
  6. Searby, Amanda; Jouventin, Pierre (2005). "The double vocal signature of crested penguins: is the identity coding system of rockhopper penguins Eudyptes chrysocome due to phylogeny or ecology?". Journal of Avian Biology. 36 (5): 449–460. doi:10.1111/j.0908-8857.2005.03416.x. ISSN 1600-048X.
  7. Hutton, FW (1879). "Southern Rockhopper Penguin (Eudyptes chrysocome)". Xeno-canto. Retrieved 8 October 2020.
  8. Xavier, J. C.; Cherel, Y.; Ceia, F. R.; Queirós, J. P.; Guimarães, B.; Rosa, R.; Cunningham, D. M.; Moors, P. J.; Thompson, D. R. (October 2018). "Eastern rockhopper penguins Eudyptes filholi as biological samplers of juvenile and sub-adult cephalopods around Campbell Island, New Zealand". Polar Biology. 41 (10): 1937–1949. doi:10.1007/s00300-018-2333-2. ISSN 0722-4060.
  9. Sagar, PM; Murdoch, R; Sagar, MW; Street, A Yardley; Thompson, DR (2005). "Rockhopper penguin (Eudyptes chrysocome filholi) foraging at Antipodes Islands" (PDF). The Ornithological Society of New Zealand. 52: 75–80.
  10. Tremblay, Y; Cherel, Y (2003). "Geographic variation in the foraging behaviour, diet and chick growth of rockhopper penguins". Marine Ecology Progress Series. 251: 279–297. doi:10.3354/meps251279. ISSN 0171-8630.
  11. Hull, Cindy L. (2000). "Comparative diving behaviour and segregation of the marine habitat by breeding Royal Penguins, Eudyptes schlegeli, and eastern Rockhopper Penguins, Eudyptes chrysocome filholi, at Macquarie Island". Canadian Journal of Zoology. 78 (3): 333–345. doi:10.1139/cjz-78-3-333. ISSN 1480-3283.
  12. "Creches". web.stanford.edu. Retrieved 20 October 2020.
  13. "Southern Rockhopper Penguin (Eudyptes chrysocome) - BirdLife species factsheet". BirdLife International. 2020. Retrieved 7 October 2020.

Further reading

Morrison, K.W; Battley, P.F; Sagar, P.M (February 2015). "Population dynamics of Eastern Rockhopper Penguins on Campbell Island in relation to sea surface temperature 1942-2012: current warming hiatus pauses a long-term decline". Biodiversity Conservation. 38 (2): 163–177. doi:10.1007/s00300-014-1575-x.

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