Justification of Red List Category
This species has a very 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 may be moderately small to large, but it is not believed to 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.
Delany and Scott (2006) estimate the population to be c.11,000 individuals.
The population is suspected to be stable in the absence of evidence for any declines or substantial threats.
This species is endemic to Australia. The subspecies pacificus breeds in Tasmania, on many Bass Strait islands and westward along the Victorian coast from Wilson's Promontory to the South Australian border. The subspecies georgii is found on the coasts of south-western Western Australia and western South Australia. Its range has expanded in recent years northwards along the Western Australian coast (Burger et al. 2018).
As with other coastal species, L. pacificus is prone to disturbance both while breeding and feeding. Most nest sites are protected, however, by their inaccessibility, and the species has proved adaptable in exploiting new food sources provided by urbanisation (Garnett and Crowley 2000). It has a diverse diet including fish, squid, intertidal molluscs, echinoderms and crabs, fish offal, carrion and refuse. Breeding occurs between September and January, either in small and open colonies or solitary (del Hoyo et al. 1996).
Reductions in the levels of zooplankton as a result of climate change is decreasing prey availability in seas throughout this species' range (Chambers et al. 2011). While not having serious negative effects on population trends at present, this threat will likely only be exacerbated in the future as the effects of climate change continue. Populations have begun contracting at the northern end of the distribution in Queensland, which is ascribed to competition with the rapidly increasing population of Kelp Gull Larus dominicanus (Burger et al. 2018).
Text account compilers
Harding, M., Martin, R., Ekstrom, J., Butchart, S., Stuart, A.
BirdLife International (2020) Species factsheet: Larus pacificus. Downloaded from http://www.birdlife.org on 06/08/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 06/08/2020.