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). 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 exceed 1,500,000 individuals.
The population is suspected to be in decline owing to predation by invasive species.
Pterodroma macroptera breeds in the Southern Hemisphere between 30 and 50 degrees south with colonies on Tristan da Cunha and Gough Island (St Helena to UK), the Crozet Islands and Kerguelen Islands (French Southern Territories), the Prince Edward Islands (South Africa), and on the coasts of southern Australia. Outside the breeding season, it disperses widely in subtropical parts of the Atlantic, Indian and Pacific Oceans, mainly between 25 and 50 degrees south, although some birds stray into the Antarctic zone (del Hoyo et al. 1992).
This marine species is highly pelagic and has a widespread, but sparse, distribution at sea. It feeds mostly on squid, with some fish and crustaceans, most of which it obtains by dipping and surface-seizing. It feeds mainly at night and may locate some cephalopods by their bioluminescence. It can occasionally be seen following cetaceans and will associate with other Procellariiformes. Breeding occurs in the winter of the southern hemisphere, starting in April. It nests either solitary or in small colonies on oceanic islands on ridges, slopes or flat ground. Breeding usually occurs below 400 m, but has been recorded as high as 1,400 m on Tristan da Cunha. It nests in burrows or above ground in rock crevices, among tree roots or under scrub (del Hoyo et al. 1992).
This species has experienced declines due to invasive predatory mammals. Cats caused a rapid decline in the species on Marion Island prior to their eradication in 1991 (Cooper et al. 1995). Despite cat eradication, subsequent recovery on Marion has been slower than expected, possibly due to breeding success remaining unexpectedly low. This has been attributed to the observed predation by mice (Dilley et al. 2018), rates of which may be increasing. Polynesian Rats are also thought to depredate nests, reducing reproductive success.
42-45 cm. A large, long-winged Pterodroma with all dark plumage and black bill. Very similar to Grey-faced Petrel Pterodroma gouldi, but the latter has a deeper bill and more extensive whitish grey face. Buoyant flight.
Text account compilers
Calvert, R., Fjagesund, T., Butchart, S., Hermes, C., Martin, R., Stuart, A., Symes, A., Ekstrom, J., Taylor, J.
BirdLife International (2019) Species factsheet: Pterodroma macroptera. Downloaded from http://www.birdlife.org on 14/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 14/11/2019.