Rationale
(Changed due to Criteria revision)
The regional population of Soft-plumaged Petrel Pterodroma mollis satisfies the criterion for Vulnerable under D2 (population with a very restricted area of occupancy, or limited to a small number of locations, which makes it vulnerable to the effects of human activities or stochastic events within a very short time period in an uncertain future, thus rendering it capable of becoming Critically Endangered or even Extinct in a very short time period). However, it was felt that it was unlikely that stochastic events or human activities at the Prince Edward islands would lead to the Soft-plumaged Petrel becoming severely threatened within one to two generations. As such the species was assessed as regionally Near Threatened.
Distribution
The Soft-plumaged Petrel breeds at several islands in the Southern Ocean including Gough, Tristan, Amsterdam, Crozet, Kerguelen, Prince Edward and Marion islands (Marchant and Higgins 1990). Outside of the breeding season, birds disperse across the Southern Ocean (Reid 2002). The species is a fairly common visitor to South African waters occurring from Namibia to KwaZulu-Natal, although it is more common to the south (Brooke 1981).
Population
The global population is estimated at 5 million mature individuals (BirdLife International 2014). Barnes and Huyser (1998) reported that Soft-plumaged Petrels breeding on Marion and Prince Edward Islands number in the thousands but do not provide a more accurate estimate. Ryan and Bester (2008) provide an estimate of 10 000 birds on Marion Island and 20 000 birds on Prince Edward Island, giving a regional population of c. 30 000 mature individuals. The population over the continental shelf and shelf-break was crudely estimated at 12 000 birds in winter and 1 200 in summer (Crawford et al. 1991). Confidence in this population estimate is low.
Population trend
The global population is thought to be stable in absence of any evidence of 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 in the early 1980s (Cooper et al. 1995). The confidence in this regional trend estimate is medium.
Threats
Predation by alien species has impacted upon Soft-plumaged Petrel numbers at several islands including Marion Island (Marchant and Higgins 1990, Cooper et al. 1995). Fortunately, removal of cats from the island in the early 1980s has nullified this threat (Cooper et al. 1995). Procellariiformes, which includes Soft-plumaged Petrel, tend to swallow more plastic than other species (Azzarello and van Vleet 1987) and retain ingested plastic more than other seabirds, primarily due to a constriction between the gizzard and proventriculus, which makes it more difficult for gizzard contents to be expelled (Furness 1985).
Conservation
Underway
No conservation measures specific to this species are in place. However, breeding populations on the Prince Edward Islands are protected. 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
None are currently proposed, as there are no overt threats to the Soft-plumaged Petrel in the region.
Research
* Information is required on population numbers and trends on Marion Island and Prince Edward Island.
* Sub-lethal impacts of marine pollutants, particularly plastic ingestion rates and impacts of this on individual health, immunocompetence and endocrine function, would be useful to assess impacts of plastic pollution, and possibly of relevance to other procellariiformes.
* Knowledge of breeding success, recruitment parameters, longevity, breeding frequency, sex-based differences in parental investment and age/sex structure would be useful for modelling population trends; currently all this information would have to be inferred from other taxa.
* Movements during and outside the breeding season are unknown, including the geographical range of juveniles.
