Justification of Red List Category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (extent of occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Convey et al. (1999) estimate a world population of ~4 million breeding pairs.
The species expanded its range and its population in the mid-20th century, potentially owing to increased prey (krill) availability (del Hoyo et al. 1992). Currently decreasing at most sites on the Antarctic Peninsula, except at the southern extreme of its range where it is increasing. Stable at the South Sandwich Island (Lynch et al. 2016). Unknown at many other locations.
This species has a circumpolar distribution, being found in Antarctica, the South Sandwich Islands (Islas Sandwich del Sur), the South Orkneys, South Shetland and South Georgia (Georgia del Sur), Bouvet Island (to Norway) and the Balleny Islands (del Hoyo et al. 1992).
Population information for many sites is unknown or out of date. For example, population surveys at the South Sandwich Islands, where the majority of the world population breeds (1,500,000 pairs; Convey et al. 1999; Lynch et al. 2016), are infrequent. Other important breeding populations exist at the South Orkney Islands (405,000 pairs; Poncet and Poncet 1985), but this is probably an underestimate (P Trathan In Litt.), especially at the western end of the archipelago. Large populations also occur at the South Shetland Islands (987,000; Trivelpiece and Trivelpiece 2013) and the west Antarctic Peninsula (72,000; Trivelpiece and Trivelpiece 2013). Small populations occur at South Georgia (~1,800 pairs), Bøuvet (<100) and at the Balleny Islands (< 100) (Trivelpiece and Trivelpiece 2013).
This species is mostly found in zones with light ice pack. Its diet is comprised almost exclusively of Antarctic krill, but it will also take fish and other species of crustaceans when possible. Prey capture is apparently by pursuit-diving up to a depth of 70 m, but mostly at depths less than 45 m. It breeds on irregular rocky coasts in ice free areas, forming large colonies of hundreds and thousands of birds (del Hoyo et al. 1992). Winter migrations can be extensive and winter habitats are generally pelagic and are located north of the sea ice edge (Hinke et al. 2015).
The recent volcanic activity during the moult period in 2016 at Zavodovski and Bristol in the South Sandwich Islands could have had severe impacts on populations; surveys of the breeding colonies at the South Sandwich Islands are therefore important to repeat. More generally, it is important to minimize human disturbance to breeding colonies; visitor site guidelines already specify minimum approach distances of 5 meters and off-limit areas.
Human impacts potentially also include disturbance from tourists, scientists, construction of new science facilities and fisheries, particularly fisheries for Antarctic krill. Harvesting of Antarctic krill could be a threat, if management does not adequately take into account the needs of species that feed upon krill. Oil spills may also be important at local scales. Protection of habitat on land and at sea is important, with the designation of appropriate protection for transit, foraging and rafting areas at sea.
Based largely upon the reported declines in the Atlantic Sector, but also recognizing that recent volcanic activity during the moult period in 2016 at Zavodovski and Bristol in the South Sandwich Islands where very large colonies occur, the threat status should be reviewed if large numbers are found to have been killed.
Conservation Actions Underway
Long-term monitoring programmes are in place at several breeding colonies.
Conservation Actions Proposed
Minimize disturbance to breeding colonies. In the Antarctic, visitor site guidelines already specify minimum approach distances of 5 meters and off-limit areas. Continue/extend long-term monitoring of breeding colonies. Monitoring studies of chinstrap populations must include annual censuses, dietary and foraging studies, reproductive research, and demographic data. Currently this information is available only from the South Shetland Islands and intermittently from the South Orkney Islands and the Palmer Archipelago. Establish similar research efforts in the South Sandwich Islands and increase research efforts in the South Orkney Islands. Gather data from the edge of the species range at South Georgia and along the Antarctic Peninsula near the southern extent of this species’ distribution. Collect information from all of these main breeding regions on distribution and diet during the non-breeding winter period.
Text account compilers
Butchart, S., Calvert, R., Ekstrom, J., Moreno, R., Trathan, P.
Schmidt, A., Lynch, H., Trathan, P., Schneider, T., DuBois, L., Fraser, W., Makhado, A., Hinke, J., Ballard, G.
BirdLife International (2018) Species factsheet: Pygoscelis antarcticus. Downloaded from http://www.birdlife.org on 18/02/2018. Recommended citation for factsheets for more than one species: BirdLife International (2018) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 18/02/2018.