Rationale
(Changed due to Criteria revision)
The regional population of South Georgian Diving Petrel Pelecanoides georgicus satisfies the criterion for regionally Vulnerable under D2 (population with a very restricted area of occupancy, or small number of locations (typically five or fewer), making it prone to effects of human activities or stochastic events, and is thus capable of becoming Critically Endangered or even Extinct in a very short time period). While it was deemed unlikely that stochastic events or human activities at the Prince Edward Islands would increase the threat status of this species so severely, there is a possibility that such activities could result in it being listed as Vulnerable or Endangered during that period. As a result, South Georgian Diving Petrel was assessed as regionally Near Threatened.
Distribution
The South Georgian Diving Petrel has a circumpolar distribution, with three distinct populations breeding in the Atlantic Ocean (on South Georgia and surrounding islets), western Indian Ocean (Prince Edward, Marion, Crozet, Kerguelen, McDonald and Heard islands) and around New Zealand (Codfish islands) (del Hoyo et al. 1992, Onley and Scofield 2007). Birds are probably sedentary, but records from Australia and south of Cape Horn suggest some dispersion (Onley and Scofield 2007).
Population
The global population is estimated at 15 million mature individuals (Brooke 2004). Rand (1954) reported the South Georgian Diving Petrel to be ‘commonly found' on Marion Island in 1948, but after the introduction of cats in the same year, numbers collapsed. In 1979 only 44 burrows were located in 21 ha (Schramm 1986). In 2011, the first confirmed breeding attempt on Marion Island in 32 years pair was recorded (McClelland et al. 2013). The Prince Edward Island population has not been impacted by introduced predators. However, little is known about population estimates although breeding populations are suspected (Barnes and Huyser 1998, McClelland et al. 2013).
Population trend
The global population is thought to be stable in the absence of any evidence showing declines (BirdLife International 2014). The regional population trend is thought to be positive due to the removal of domestic cats Felis catus from Marion Island (Cooper et al. 1995). The confidence in this regional trend estimate is medium.
Threats
Human disturbance on breeding islands and introduced predators are the main threats to the South Georgian Diving Petrel (Brooke 2004). The Marion Island population was severely impacted by cats, however this threat was removed when the last cat was eradicated in 1991 (Bester et al. 2002). Despite this, no active burrows were recorded until 2011 (McClelland et al. 2013), showing the slow recovery from cat predation, and perhaps an indication that other unknown threats are preventing this population from recovering. Prince Edward Island is free from introduced predators (de Villiers and Cooper 2008) and although breeding there has not been confirmed, there are no known threats to the suspected breeding population.
Conservation
Underway
No species-specific conservation measures are currently underway, but various generic conservation measures are in place at its breeding islands. 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 managed under the Prince Edward Islands Management Plan 1996. The Prince Edward Islands Marine Protected Area was proclaimed in 2013.
Proposed
No conservation actions are currently recommended, as there are no overt threats to this species in the region.
Research
* Information is required on population numbers and trends on Marion and Prince Edward islands.
* Virtually nothing is known about many basic demographic parameters, at-sea distributions, habitat preferences, or foraging ecology for this species at the Prince Edward islands or elsewhere.
* Movements of this species are poorly known.
