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 stable, 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.
Brooke (2004) estimated the global population to number at least 5,000,000 individuals.
The population is suspected to be stable in the absence of evidence for any declines or substantial threats.
The Soft-plumaged Petrel breeds on islands in the Southern Hemisphere, nesting on Tristan da Cunha and Gough Island (St Helena to UK), the Prince Edward Islands (South Africa), Crozet Islands (French Southern Territories) and on the Antipodes Islands (New Zealand). It disperses outside the breeding season, reaching eastern South America north to Brazil, South Africa, Australia and New Zealand (del Hoyo et al. 1992).
This marine species is highly pelagic and rarely approaches land, except at breeding colonies. It feeds mostly on cephalopods but will also take crustaceans and fish, which are taken mainly by surface-seizing. Breeding starts in September in colonies on oceanic islands. It occupies steep slopes with tussock grass or ferns, usually along the coast but also inland. Pairs nest in long burrows (del Hoyo et al. 1992).
This species is primarily affected by invasive mammalian predators. On Marion Island the population was drastically reduced through hunting by cats prior to their eradication in 1992 (Cooper et al. 1995). On Gough Island, where the population was an estimated 1.5 million pairs in 2001 (Brooke 2004), recent years have seen very low breeding success and burrow occupancy attributable to the action of predatory mice (Cuthbert et al. 2013). Predation by rats is considered likely to have impacted this species on the islands where rats have become established with severe declines noted in some locations (Carboneras et al. 2018).
Text account compilers
Calvert, R., Fjagesund, T., Hermes, C., Martin, R., Butchart, S., Stuart, A., Ekstrom, J.
BirdLife International (2019) Species factsheet: Pterodroma mollis. Downloaded from http://www.birdlife.org on 20/05/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 20/05/2019.