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 very 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 around 300,000 individuals.
The population is suspected to be in decline owing to ongoing threats.
This species ranges widely over most oceans in the southern Hemisphere, breeding on Lord Howe Island (Australia), the Kermadec Islands (New Zealand), the Austral Islands (French Polynesia) and Juan Fernández Islands (Chile) in the Pacific Ocean, Tristan da Cunha and Gough Island (St Helena to U.K.) in the Atlantic Ocean, and Île Saint-Paul (French Southern Territories) in the Indian Ocean (del Hoyo et al. 1992).
This marine species is highly pelagic and rarely approaches land except when near colonies. It feeds mostly on squid with some crustaceans which it catches on the wing by pattering and dipping. It has been recorded feeding in the company of other seabirds and following ships. It forms loose colonies on offshore islands or stacks, generally amongst boulder scree or on grassy slopes up to 450 m above sea level, nesting in rock crevices or burrows (del Hoyo et al. 1992).
Thought to ingest considerable amounts of plastic waste. The presence of plastics in a bird’s gizzard may cause gastrointestinal blockage (Day 1980 in Azzarello and Van Vleet 1987); depression of feeding activity by sustaining stomach distention, a stimulus normally associated with satiety (Sturkie 1965 in Azzarello and Van Vleet 1987, Ryan 1988); and a reduction in meal size (Ryan 1988), but population level impacts have not been documented.
Text account compilers
Stuart, A., Butchart, S., Fjagesund, T., Harding, M., Ekstrom, J., Calvert, R., Hermes, C., Martin, R., Miller, E.
BirdLife International (2021) Species factsheet: Fregetta grallaria. Downloaded from http://www.birdlife.org on 24/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 24/10/2021.