Overview

Brief Summary

Biology

A gregarious species, the northern rockhopper penguin breeds in large colonies that may comprise over a hundred thousand nests. Breeding pairs are monogamous, and usually return to the same nest every year (2). Egg-laying commences around August (3), with the female usually producing a clutch of two eggs of unequal size (2). Usually only the chick from the larger egg survives to maturity. Incubation takes around 33 days, with both parent birds taking it in turns to sit on the eggs for extended periods of a time, whilst the other forages for food. Incubation is aided by a bare patch of skin on the lower abdomen (known as a 'brood pouch') that allows greater heat transfer to the egg. Once hatched, the male will remain to brood the chick for the first 25 days, whilst the female regularly brings food back to the nest. After this time, the chick is able to leave the nest, and will congregate with other chicks in small groups known as 'crèches' whilst the parent birds forage (2). In order to maintain its waterproof coat, the northern rockhopper penguin engages in frequent grooming, which 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. After breeding the northern rockhopper penguin forages extensively in order to build up fat reserves in preparation for its annual moult. It takes around 25 days for the penguin's coat to be fully replaced, at which point it leaves the land and spends the winter months foraging at sea, before returning to shore to breed in the following spring (2). The diet of the northern rockhopper penguin is composed of a variety of oceanic species, such as crustaceans, squid, octopus and fish (4). Groups may often feed together and dives may be to depths of up to 100 metres (2).
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Description

Previously classed as a single species, the rockhopper penguin has now been split into a northern (Eudyptes moseleyi) and southern species (Eudyptes chrysocome) (3). Although both species are similar in appearance, the distinctive yellowish plumes extending from the yellow line above the eye are significantly longer and denser in the northern rockhopper penguin (2) (3). The body is small but robust, with slate-grey upperparts and white underparts, the bill is short and reddish-brown and the eyes are red. Juveniles can be identified by the lack of adult yellow markings (2).
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Distribution

Range Description

Eudyptes moseleyi is found in the South Atlantic and Indian Ocean. It has a restricted breeding range, occurring on just seven islands with a total land area of 250 km2. The majority are found on Gough Island and islands in the Tristan da Cunha group (St Helena to UK), with 83,000 pairs on Middle Island (2009), 64,700 pairs on Gough (2006), 25,000 pairs on Nightingale (2009), 54,000 pairs on Inaccessible (2009) and 6,700 pairs on Tristan (2009) (BirdLife International 2010, BirdLife International 2012). The rest of the population is found in the India Ocean with 24,890 pairs on Amsterdam Island and 9,023 pairs on St Paul Island (French Southern Territories). Early records indicate that millions of penguins used to occur on both Tristan da Cunha and Gough Island. Approximately 2 million pairs (98%) were lost from Gough Island between 1955 and 2006 and Tristan da Cunha is thought to have held hundreds of thousands of pairs in the 1870s, which were reduced to around 5,000 pairs by 1955 (Cuthbert et al. 2009). The breeding colonies on Amsterdam and St Paul Islands have reduced in size by 40% (Guinard et al. 1998). Population modelling, based on those breeding sites that have been accurately surveyed, indicates that over the past 37 years (= 3 generations) the number of Northern Rockhopper Penguins has declined by 57% (Birdlife International 2010).

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Range

Tristan da Cunha, Gough, St. Paul and Amsterdam islands.
  • Clements, J. F., T. S. Schulenberg, M. J. Iliff, D. Roberson, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2014. The eBird/Clements checklist of birds of the world: Version 6.9. Downloaded from http://www.birds.cornell.edu/clementschecklist/download/

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Range

The northern rockhopper penguin breeds on a number of Southern Ocean islands, with the largest populations found on the islands of Tristan da Cunha and Gough, and additional, smaller populations on the islands of Amsterdam and St Paul (4).
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
Adults arrive at the breeding colonies in late July and August. Nests are located in a variety of habitats ranging from open boulder-strewn beaches on Gough Island to among stands of tussock grass (mainly Spartina arundinacea) on Nightingale and Inaccessible islands (Cuthbert 2012). They feed mainly on krill. Other prey items include other crustaceans, squid, octopus and fish (Williams 1995).


Systems
  • Marine
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Nesting occurs on cliffs and rocky gullies, and chosen sites are usually situated near to freshwater, either natural springs or puddles (2).
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
EN
Endangered

Red List Criteria
A2acde+3cde+4acde

Version
3.1

Year Assessed
2012

Assessor/s
BirdLife International

Reviewer/s
Symes, A. & Butchart, S.

Contributor/s
Cuthbert, R. & Hilton, G.

Justification
This species has been classified as Endangered owing to very rapid population decreases over the last three generations (30 years) throughout its range. Precise reasons for the declines are poorly known, but changes in sea temperature, competition and incidental capture in fisheries and introduced predators are all likely to be implicated.

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Status

Classified as Endangered (EN) on the IUCN Red List (1).
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Population

Population
The population is estimated at around 265,000 breeding pairs (Birdlife International 2010, BirdLife International 2012). The majority are found on Gough Island and islands in the Tristan da Cunha group (St Helena to UK), with 83,000 pairs on Middle Island (2009), 64,700 pairs on Gough (2006), 25,000 pairs on Nightingale (2009), 54,000 pairs on Inaccessible (2009) and 6,700 pairs on Tristan (2009) (BirdLife International 2010, BirdLife International 2012). The rest of the population is found in the India Ocean with 24,890 pairs on Amsterdam Island (1993) and 9,023 pairs on St Paul Island (1993) (French Southern Territories). Several populations have experienced major long-term population crashes. Approximately 2 million pairs (98%) were lost from Gough Island between 1955 and 2006 and Tristan da Cunha is thought to have held hundreds of thousands of pairs in the 1870s, which were reduced to around 5,000 pairs by 1955 (Cuthbert et al. 2009). The breeding colonies on Amsterdam and St Paul Islands have reduced in size by 40% (Guinard et al. 1998). Population modelling, based on those breeding sites that have been accurately surveyed, indicates that over the past 37 years (= 3 generations) the number of Northern Rockhopper Penguins has declined by 57% (Birdlife International 2010).

Population Trend
Decreasing
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Threats

Major Threats
Egg collection was common at some colonies until the 1950s, such as on Tristan da Cunha, and may continue on Nightingale, perhaps causing decreases (Richardson 1984, P. G. Ryan in litt. 1999). Penguins were taken historically as bait for use in crab pots at a number of sites, including at St Paul (Indian Ocean) and Tristan da Cunha. The only reported cases of major predation by invasive species are feral pigs on Tristan and Inaccessible (where pigs were eradicated in 1873 and 1930, respectively). Domestic and feral dogs were also reported to be a problem on Tristan da Cunha (BirdLife International 2010). Food supplies may be affected by squid fisheries, climate change and shifts in marine food webs (Cunningham and Moors 1994, Guinard et al. 1998, Hilton et al. 2006). Increasing disturbance and pollution results from ecotourism and fishing (Ellis et al. 1998). Driftnet fishing and rock-lobster fisheries have caused significant mortality (Ryan and Cooper 1991, P. G. Ryan in litt. 1999). One possible ‘top-down’ effect on the eudyptid penguins is competition with pinnipeds–especially subantarctic fur seals Arctocephalus tropicalis (Barlow et al. 2002). In early 2011, a cargo ship ran aground on Nightingale Island. The resultant oil spill reached Inaccessible Island and Tristan more than 30km away. Early indications are that the impact on the breeding population has not been as severe as initially feared (BirdLife International 2012).

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A recent study of the northern rockhopper penguin population (published in 2009), has shown that well over one million birds have been lost from the breeding colonies on the islands of Tristan da Cunha and Gough. While this equates to declines of over 90 percent on both islands, on Gough this loss has occurred in just 45 years, whereas on the main island of Tristan, it has taken almost three times longer. The reasons for the swift decline on Gough are currently unknown, but the penguin may be suffering increased levels of predation, as well as competition for food, from the rapidly rising population of Subantarctic Fur Seals Arctocephalus tropicalis (5). Other factors may include increasing disturbance and pollution, introduced predators, reduced food supplies due to overfishing, and climate change (4).
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Management

Conservation Actions

Conservation Actions
Conservation Actions Underway
Regular monitoring is, or will be, undertaken on Tristan da Cunha, Gough, Amsterdam and St Paul Islands (Cuthbert and Sommer 2004, Cuthbert and Sommer 2004). Several ecological and demographic studies have been undertaken (Ellis et al. 1998, Guinard et al. 1998). Many islands with breeding colonies are reserves. An International Species Action Plan and a series of Regional Action Plans have been developed (BirdLife International 2010).

Conservation Actions Proposed
Continue or start to monitor all populations to assess trends. Conduct long-term demographic studies to understand the causes of current decline (BirdLife International 2010). Conduct research into spatial and temporal links between population trends, sea surface temperature and primary productivity (BirdLife International 2010). Conduct studies to assess interactions with commercial fisheries (Ryan and Cooper 1991). Study the potential impacts of climate change. Assess the threat from introduced predators.

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Conservation

While the northern rockhopper penguin population is being regularly monitored, in order to safeguard against further declines, it is imperative that the causes of the population crash be determined (4) (5). This should be targeted at all possible factors, including studies of interactions with commercial fisheries, the impact of the introduced predatory house mouse on chick survival on Gough Island (4), and the effects of fur seal predation and competition (5). Without the implementation of appropriate conservation measures, this charismatic species will continue to nose dive towards extinction (5).
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Wikipedia

Northern rockhopper penguin

The northern rockhopper penguin, Eudyptes c. moseleyi, is usually considered a subspecies of rockhopper penguin, although fairly recent studies show evidence of distinction from the southern rockhopper penguin group Eudyptes c. chrysocome/E. c. filholi.

A study published in 2009 showed that the population of the northern rockhopper had declined by 90% since the 1950s. For this reason, the northern rockhopper penguin is classified as endangered.

Taxonomy[edit]

The rockhopper penguins have been considered to consist of two species, northern and southern rockhopper penguin, since research published in 2006 demonstrated morphological, vocal, and genetic differences between the two populations.[2][3] Molecular datings suggest that the genetic divergence with the southern rockhopper penguin may have been caused by a vicariant event caused by a shift in the position of the Subtropical Front during the mid-Pleistocene climate transition.[4] Analysis of a part of a mitochondrial control region from a northern rockhopper penguin found on the Kerguelen Islands showed that it may have come from Gough Island, 6,000 km away, and that the southern and northern rockhoppers are genetically separate, though some individuals may disperse from their breeding colonies.[5] Many taxonomists have yet to recognize the split, although some are beginning to do so.

Distribution and habitat[edit]

More than 99% of northern rockhoppers breed on Tristan da Cunha and Gough Island in the south Atlantic Ocean.[6]

Ecology and behaviour[edit]

Food and feeding[edit]

The northern rockhopper penguin feeds on krill and other sea life such as crustaceans, squid, octopus and fish.[6]

Breeding[edit]

It breeds in colonies in a range of locations from sea level or on cliff sides, to sometimes inland.[6]

Population and threats[edit]

Northern rockhopper penguins on Inaccessible Island, drawn by the naturalist aboard HMS Challenger

The current population is estimated to be between 100,000–499,999 breeding pairs at Gough Island, 18,000 to 27,000 pairs at Inaccessible Island, and 3,200 to 4,500 at Tristan da Cunha. In the Indian Ocean, the population was 25,500 pairs on Amsterdam Island, and 9,000 pairs on St Paul Island in 1993; there has been no information available on population trends there since the 1990s. Declines at the Atlantic Ocean sites show a decline of 2.7% per year;[6] the drop in the population at Gough Island has been described as equivalent to the loss of 100 birds every day since the 1950s.[7]

A study published in 2009 showed that the world population of the northern rockhopper had declined by 90% since the 1950s, possibly because of climate change, changes in marine ecosystems and overfishing for squid and octopus by humans.[8] Other possible factors in the decline include disturbance and pollution from ecotourism and fishing, egg-harvesting, predation from introduced house mice (Mus musculus) and predation and competition from subantarctic fur seals (Arctocephalus tropicalis).[6]

The northern rockhopper penguin is classified as endangered because of the decline in numbers over the last three generations (or 30 years).[6]

2011 oil spill[edit]

On March 16, 2011, the Maltese-registered freighter MS Oliva ran aground on Nightingale Island, spilling tons of heavy crude into the ocean. The crew was rescued, but the ship broke up, leaving an oil slick that surrounded the island, threatening its population of rockhopper penguins.[9][10] Nightingale Island has no fresh water, so the penguins were transported to Tristan da Cunha for cleaning.[11]

In culture[edit]

References[edit]

  1. ^ BirdLife International (2012). "Eudyptes moseleyi". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013. 
  2. ^ Jouventin P., Cuthbert R.J., Ottvall R. (2006). Genetic isolation and divergence in sexual traits: evidence for the Northern Rockhopper Penguin Eudyptes moseleyi being a sibling species. Molecular Ecology 15:3413-3423.
  3. ^ Banks J., Van Buren A., Cherel Y., Whitfield J.B. (2006). Genetic evidence for three species of Rockhopper Penguins, Eudyptes chrysocome. Polar Biology 30:61-67.
  4. ^ de Dinechin, M., Ottvall R., Quillfeldt P. & Jouventin P. (2009). Speciation chronology of northern rockhopper penguins inferred from molecular, geological and palaeoceanographic data. Journal of Biogeography 36(4):693–702.
  5. ^ de Dinechin M., Pincemy G., Jouventin P. (2007) A northern rockhopper penguin unveils dispersion pathways in the Southern Ocean Polar Biology 31(1):113-115
  6. ^ a b c d e f BirdLife International (2008). Species factsheet: Eudyptes moseleyi. Retrieved 16 January 2009.
  7. ^ msnbc.com. Northern rockhopper penguins near extinction. 16 January 2009. Retrieved 18 March 2009.
  8. ^ BirdLife International. Penguins are walking an increasingly rocky road. 16 January 2009. Retrieved 16 January 2009.
  9. ^ "MS Oliva runs aground on Nightingale Island". The Tristan da Cunha Website. Retrieved 23 March 2011. 
  10. ^ "Oil Spill Menaces Penguins". Science 331: 1499. 25 March 2011. doi:10.1126/science.331.6024.1499-b. 
  11. ^ BBC News Oil-soaked rockhopper penguins in rehabilitation
  12. ^ Surf's Up at IMDb
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