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 15,000,000 individuals.
The population is suspected to be declining owing to predation from invasive species.
This species breeds on Gough Island and Tristan da Cunha (St Helena to UK) in the south Atlantic, and on the Chatham Islands, New Zealand and south of New Zealand's south island. Adults are thought to remain in waters adjacent to colonies; however young birds occur north of the colonies to Australia and South Africa1.
The diet of this species is comprised mostly of cruaceans (especially copepods), squid and some fish. It apparently takes more crustaceans in summer and small squid in winter. Prey is obtained usually by hydroplaning and by filtering or surface-seizing. Breeding starts in July or August and individuals are strongly colonial, nesting in burrows which are sometimes occupied by more than one pair. It breeds on a large variety of substrates and areas; coastal slopes, flat lava fields, offshore islets and cliffs, dry rocky soil, caves and scree (del Hoyo et al. 1992).
Text account compilers
Newton, P., Butchart, S., Ekstrom, J., Calvert, R.
BirdLife International (2017) Species factsheet: Pachyptila vittata. Downloaded from http://www.birdlife.org on 12/12/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 12/12/2017.