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The regional population of Southern Rockhopper Penguin Eudyptes chrysocome at the Prince Edward Islands underwent an observed decline of greater than 50% over three generations satisfying the criterion A2 for regionally Endangered. Furthermore this decline is predicted to continue over the next three generations.
The subspecies E. c. chrysocome occurs in southern Chile, Argentina, at the Falkland Islands and South Georgia in the south-west Atlantic Ocean. E. c. filholi occurs at the Prince Edward Islands, Crozet Islands, Kerguelen Islands and Heard Island in the south Indian Ocean and at Macquarie, Campbell, Antipodes and Auckland islands in the south-west Pacific Ocean. Its latitudinal range for breeding varies from 46° S at the Crozet Islands to 54° S at Macquarie Island (BirdLife International 2014al).
The global population has been quantified at 1 000 000-2 499 999 mature individuals (BirdLife International 2014al). In 2012/13, 65 000 pairs of Southern Rockhopper Penguins were counted at Marion Island, compared to 173 000 pairs in 1994/95 (Department of Environmental Affairs, unpubl. data). An estimated 38 000 pairs bred at Prince Edward Island in 2008 (Crawford et al. 2009c). Combined, the overall population at the Prince Edward Islands is of the order of 94 000-103 000 pairs. Confidence in this population estimate is high.
The global population is thought to have undergone a decline of c. 30% over the last three generations (30 years), which has been driven largely by the declines in the Falklands (where data are most complete), and to a lesser extent, Marion Island (BirdLife International 2014al). In 1987/88, 137 652 pairs of Southern Rockhopper Penguins were counted at Marion Island, increasing to 173 000 pairs in 1994/95. This fell to c. 61 000 pairs in 2008/09 (Crawford et al. 2003e, Crawford et al. 2009c). Just 56 000 pairs were counted in 2009/10 (Department of Environmental Affairs unpubl. data). Between 1994/95 and 2012/13, nine whole-island counts of Southern Rockhopper Penguins at Marion Island indicated a significant decrease in the population (Department of Environmental Affairs, unpubl. data). At Prince Edward Island, counts of Southern Rockhopper Penguins decreased from 45 000 pairs in 2001 to 38 000 pairs in 2008, despite better coverage in the latter period (BirdLife International 2014al). The decrease in counts between 1987/88 and 2012/13 was 52% in 25 years, equivalent to 72% over three generations. Confidence in this population trend estimate is high.
Inadequate breeding success has been a major factor driving the decrease of Southern Rockhopper Penguins at Marion Island (Crawford et al. 2003e). Overwintering conditions are thought to influence the proportions of penguins skipping breeding, and breeding success, at Marion Island (Crawford et al. 2006). In winter, penguins from Marion Island forage mostly to the north-east of the island. Mass of individual birds returning to Marion Island to breed decreased by about 20% between 1994/95 and 2007/08 and was significantly correlated with breeding success (Crawford et al. 2008c) and global climate change may have altered availability of prey to rockhopper penguins (Cunningham and Moors 1994, Guinard et al. 1998). In 1992, 1993 and 2004, disease, including avian cholera Pasteurella multocida, killed substantial numbers of King Penguins Aptenodytes patagonicus and Macaroni Penguins Eudyptes chrysolophus at Marion Island (Cooper et al. 2009). Avian cholera also caused deaths of Southern Rockhopper Penguins at Campbell Island (Cunningham and Moors 1994). There have been large decreases of Southern Rockhopper Penguins at Campbell Island in the south-west Pacific Ocean (Cunningham and Moors 1994) and at the Falkland Islands in the south-west Atlantic Ocean (Pütz et al. 2003) but the ecological and demographic drivers of rockhopper penguin decreases are not fully understood (BirdLife International 2014al).
At the Falkland Islands, fisheries may have reduced quantities of fish and squid available to Southern Rockhopper Penguins (Bingham 2002). Starvation and poisoning from harmful algal blooms may cause die-offs of rockhopper penguins (BirdLife International 2014al). An oil spill killed substantial numbers of Northern Rockhopper Penguins at Nightingale Island (Tristan da Cunha Islands) in 2011. There is some indication that rockhopper penguins have declined at several sites where there have been major recoveries of fur seals Arctocephalus spp. (BirdLife International 2014al). Recoveries of fur seals at the Prince Edward Islands (Bester et al. 2009) could increase competition for prey and predation of penguins. Giant petrels Macronectes spp., Subantarctic Skuas Stercorarius antarcticus and Lesser Sheathbills Chionis minor also may inflict mortality (BM Dyer pers. obs.).
At Marion Island, there are strict guidelines in place for offloading diesel. Poultry products supplied to the over-wintering teams at Marion Island, or used during relief voyages to the island, do not contain bones and are irradiated in order to reduce the risk of introducing avian diseases. A contingency plan is in place to guide responses to outbreaks of disease at the Prince Edward Islands. No access is allowed to Prince Edward Island except for bona fide research and conservation purposes every 4-5 years. The Prince Edward Islands Marine Protected Area was proclaimed in 2013. The Prince Edward Islands are listed as a Ramsar Wetland of International Importance, as a Special Nature Reserve under the Environment Conservation Act (No 73 of 1989) and the Prince Edward Islands Management Plan 1996.
A Population and Habitat Viability Assessment (PHVA) is recommended, as is a Biodiversity Management Plan, culminating in a National Species Recovery Plan. Monitoring of population numbers and demographic, diet and condition parameters at Marion Island should be continued. A population census at Prince Edward Island should be undertaken at intervals of about five years. Best-practice guidelines for reducing risk of disease outbreaks at islands are being developed by the Agreement on the Conservation of Albatrosses and Petrels. Once available, these guidelines should replace those presently operating at the Prince Edward Islands. Overwintering teams should be given basic training in the rescue and rehabilitation of oiled penguins. The impact of any proposed fishery on the prey of Southern Rockhopper Penguins should be carefully assessed before such a fishery is allowed. Consideration should be given to declaring marine protected areas at important feeding grounds of Southern Rockhopper Penguins.
* It is important to understand how food availability for Southern Rockhopper Penguins fluctuates at both summer and winter feeding grounds, and to what extent the penguins compete with other predators for prey.
* Further information is required on the foraging distributions, especially during breeding, and on adult and immature survival and age at breeding of Southern Rockhopper Penguins at Marion Island.
* Levels of mortality attributable to avian and mammalian predators should be reassessed.
* Proposed implantation of transponder tags may assist in determining both population and demographic parameters.
* Further counts of Southern Rockhopper Penguins are required for Prince Edward Island.