Data Zone
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.
Population justification
Brooke (2004) estimated the global population to number at least 7,000,000 individuals.
Trend justification
The population is suspected to be stable in the absence of evidence for any declines or substantial threats.
The Thin-billed Prion breeds the Crozet Islands and the Kerguelen Islands (French Southern Territories), the Falkland islands (Islas Malvinas) and Noir Island, Chile. Outside the breeding season it can be found over much of the Southern Ocean, including the coasts of South Africa, Australia and South America as far north as Uruguay and southern Peru.
This marine species can usually be found over pelagic waters but will feed inshore or in shallow offshore waters during the breeding season. It feeds mostly on crustaceans with a heavy dependance on amphipods (particularly Themisto gaudichaudii) but can also take small fish and squid. It catches prey mainly by surface-seizing, dipping and pattering at night. Breeding starts in October in loose colonies in costal areas with soft or stony soil and low vegetation. It nests in burrows (del Hoyo et al. 1992).
The largest colony of Slender-billed Prion, on New Island in the Falklands, has suffered predation from cats Felis catus and rats Rattus spp., but appears naturally resilient to this pressure (Hilton and Cuthbert 2017) and eradications have further quashed any population impacts (Carboneras et al. 2018). Cat predation is however ongoing on Kerguelen, and may be having impacts here alongside predation from skuas Catharacta spp. on nonbreeding birds (Carboneras et al. 2018).
Text account compilers
Ekstrom, J., Calvert, R., Fjagesund, T., Hermes, C., Butchart, S., Martin, R., Newton, P., Stuart, A.
Recommended citation
BirdLife International (2024) Species factsheet: Slender-billed Prion Pachyptila belcheri. Downloaded from
https://datazone.birdlife.org/species/factsheet/slender-billed-prion-pachyptila-belcheri on 19/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 19/12/2024.