Justification of Red List Category
This species has a very 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). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to 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.
Brooke (2004) estimated the global population to number around 15,000,000 individuals.
The population is suspected to be in decline owing to predation by invasive species (de Hoyo et al. 1992), and other ongoing threats.
The South Georgia Diving-Petrel has a circumpolar distribution, breeding on South Georgia (Georgias del Sur) in the south Atlantic and on the Prince Edward Islands (South Africa), Crozet and Kerguelen Islands (French Overseas Territories) and Heard Island (Australia) in the southern Indian Ocean. In New Zealand, it breeds on Codfish Island (del Hoyo et al. 1992).
This marine species is found offshore or in cool pelagic waters. It feeds mainly on planktonic crustaceans, particularly krill, but will also feed on some small fish and young cephalopods. Prey are caught under water in a pursuit-dive or by surface-seizing. It breeds between October and February in colonies on oceanic islands amongst scree or volcanic ash above the tree line, or under sand dunes in areas of relatively flat ground. It nests in burrows with an end chamber. Little is known about its movements but it is presumably sedentary (del Hoyo et al. 1992).
Rats Rattus spp. are present in multiple colonies where this species breeds. While in some areas, such as South Georgia, comprehensive eradiaction programems are being carried, this threat is likely to continue with decreasing severity for the forseeable future (Piertney et al. 2016). However, this species is not noted as being particularly susceptible or severely affected by this threat. The South Georgia Diving-petrel is hunted by locals for their white feathers to use in fishing lures, thought to be causing slow declines (Taylor 2013). Habitat erosion after a severe weather event in 2003 has led to significant declines in the species' colony on Codfish Island, New Zealand (Taylor 2013), habitat degradation is also occurring due to the expansion of forest habitat into the dune region and choking of burrows by the roots of invasive grass species (Taylor 2013).
Text account compilers
Bennett, S., Ekstrom, J., Calvert, R., Butchart, S., Martin, R., Stuart, A.
BirdLife International (2019) Species factsheet: Pelecanoides georgicus. Downloaded from http://www.birdlife.org on 22/04/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/04/2019.