Open image gallery
The population of the Macaroni Penguin Eudyptes chrysolophus breeding at the Prince Edward Islands was assessed as regionally Vulnerable, having satisfied Criterion A2 with a decrease of 30%, the causes of which may not have ceased, are not fully understood and may not be reversible.
The Macaroni Penguin has a more southerly distribution than most other crested penguins, breeding between about latitudes 45°S and 65°S in the western Indian Ocean (on Heard and McDonald, Kerguelen, Crozet and Prince Edward islands groups) and the South Atlantic Ocean (Bouvet, South Sandwich, South Georgia, South Orkney, South Shetland and Falkland islands, and in small numbers at islands off the Antarctic Peninsula) (Poncet 1993). It also extends into the south-east Pacific along the coast of southern Chile. The largest colonies are north of 55°S (Marchant and Higgins 1990).
The global population is estimated at 6.3 million breeding pairs in at least 258 colonies at c. 55 breeding sites (Crossin et al. 2013), with key populations on Isles Crozet (2.2 million pairs, including 1 million on Ilots des Pingouins), Kerguelen (1.8 million pairs), Heard Island (1 million pairs), South Georgia (1 million pairs) and Marion Island. In 2012/13, it was estimated that 266 971 pairs of Macaroni Penguins bred at Marion, compared to 433 723 pairs in 1994/95 (Crawford et al. 2003, 2009). A linear regression fitted to the data suggests that the population in 2012/13 was 278 000 pairs. An estimated 12 000 pairs bred at Prince Edward Island in 2008/09 (Crawford et al. 2009). The overall population at the Prince Edward Islands is estimated at 279 000-290 000 pairs. Confidence in this estimate is high.
The current global population estimate of 6.3 million breeding pairs (Crossin et al. 2013) represents a 30% reduction on the previous estimate of 9 million pairs (Woehler and Croxall 1997). It was estimated that there were 449 892 pairs of Macaroni Penguins on Marion Island in 1974-1977 (Siegfried et al. 1978), based on counts of small colonies and at two large colonies (Bullard Beach and Kildalkey Bay), measurements of areas occupied and densities of nests, or 1974-1977 counts of moulting birds made from aerial photographs. 405 084 pairs were present in the 1983/84 breeding season (Watkins 1987) and 433 723 pairs in 1994/95 (Crawford et al. 2003).
It was then estimated that by 2008/09 numbers breeding had decreased by 32% (Crawford et al. 2009). By 2008/09, there were significant decreases in numbers breeding at the small colonies and at both of the large colonies, where densities of nests also decreased significantly (Crawford et al. 2009). In 2012/13, 266 971 pairs bred at Marion Island. Therefore, between 1976/77 and 2012/13, a period of 36 years, estimates of the numbers breeding decreased by 41%.
Numbers breeding at Marion Island were available for each season between 1994/95 and 2012/13 (Crawford et al. 2003, 2009). In this period, the estimated population in 1994/95 was 416 000 pairs and that in 2012/13 was 278 000 pairs. This is equivalent to a decrease of 33% in 19 years. Confidence in this trend estimate is high.
Inadequate breeding success has been a factor in the decrease of Macaroni Penguins at Marion Island (Crawford et al. 2003). Overwintering conditions are thought to influence the proportions of Macaroni Penguins skipping breeding, and therefore population-level breeding success; feeding conditions during breeding also may influence breeding success (Crawford et al. 2006). Global climate change may have altered the availability of prey to Macaroni Penguins (Crawford et al. 2003). In winter, Macaroni Penguins from Marion Island forage mostly to the south of the island, sometimes approaching the edge of the sea-ice (J-B Thiebot et al. unpubl. data). No fisheries currently target the main prey of Macaroni Penguins at the Prince Edward Islands, but should the fishery industry be introduced this would potentially decrease prey availability (BirdLife International 2014). Longline fisheries at winter feeding grounds have inflicted limited incidental mortality on Macaroni Penguins (BM Dyer unpubl. data).
Recoveries of numbers of fur seals Arctocephalus spp. at the Prince Edward Islands (Hofmeyr et al. 2006, Bester et al. 2009) could increase competition for prey and lead to increased predation of Macaroni and other penguins by seals. Increasing seal herds could also block access to penguin breeding sites, thereby inhibiting colony growth, as happened at Bouvet Island (Isaksen et al. 1997). Giant petrels Macronectes spp., Subantarctic Skuas Stercorarius antarcticus and Lesser Sheathbills Chionis minor also inflict mortality (BM Dyer pers. obs.).
Macaroni Penguins are susceptible to outbreaks of disease, including avian cholera Pasteurella multocida; disease outbreaks killed substantial numbers of Macaroni Penguins at Marion Island in 1992, 1993 and 2004 (Cooper et al. 2009). Oil spills around breeding colonies could be catastrophic.
Macaroni Penguins breeding at the Prince Edward Islands are indirectly protected, along with all other seabirds on the islands, by a number of regulations. For example, 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 itself, except for bona fide research and conservation purposes every 4-5 years. The Prince Edward Islands are listed as a Ramsar Wetland of International Importance, and as a Special Nature Reserve under the Environment Conservation Act (No 73 of 1989) and the Prince Edward Islands Management Plan 1996. The Prince Edward Islands Marine Protected Area was proclaimed in 2013.
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 Macaroni 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 Macaroni Penguins.
* Monitoring of mortality rates, population numbers and population trends in the Grey Petrels breeding at the Prince Edward islands should be a priority.
* Trends or changes in adult and juvenile survival rates, and the factors impacting upon this, should be investigated.
* Levels of overlap with fishing operations and incidence of bycatch should be documented, so that mitigation measures can be implemented.