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Subspecies Conservation Summary Antarctic Tern (New Zealand) Sterna vittata bethunei Buller, 1896 Laridae Conservation status Australian breeding population: Endangered D Population visiting Australia: Least Concern Reasons for listing Population <250 mature individuals Status 2000 Australian breeding population: Endangered D Population visiting Australia: Least Concern Status 1990 Australian breeding population: Endangered D Population visiting Australia: Least Concern Taxonomy S. v. vittata (Heard I.) is Endangered in Australia, 3 extralimital subspecies occur in the South Atlantic. The species is Least Concern. Taxonomic uniqueness: medium (14 genera/family, 15 species/genus, 5 subspecies/species) Range In Australian territory, breeds on offshore stacks off Macquarie I. Extralimitally, breeds on Stewart I. and subantarctic islands of New Zealand. Some individuals from the Macquarie I. population remain in the area throughout the year, while others may disperse as far north as Australia and New Zealand. Otherwise, little is known about its movements outside the breeding season (Higgins and Davies 1996). 40 pairs were recorded on Macquarie I. (Rounsevell and Brothers 1984). Up to 1000 birds breed on New Zealand’s subantarctic islands (Higgins and Davies 1996). Ecology Nests usually in live vegetation, though occasionally in unvegetated crevices. During summer, mostly feeds on small fish, but also crustaceans and other marine invertebrates in kelp beds near the island. During winter, they feed at the edge of ice and in patches of unfrozen inshore water (Higgins and Davies 1996). A generation length of 11.0 years (BirdLife International 2011) is derived from an age of first breeding of 3.2 years, a maximum age in the wild of 23.1 years and an adult survival of 82.4%, all extrapolated from congeners. Abundance There are no estimates of population size before exotic predators were introduced, but the population was apparently small in the early 20th century (Hamilton 1894). The most recent population estimate is from 1979, when Threats The absence of nesting terns from the main island of Macquarie I. suggests that predation by Black Rats Rattus rattus, and formerly feral cats Felis catus and Wekas Gallirallus australis, has historically reduced the population size. The species is also vulnerable to human disturbance, but is probably stable while the offshore stacks are free of rats. Erosion and landslips caused by over-grazing by Current eligibility against IUCN Red List Criteria IUCN Red List assessment data IUCN category Criteria eligibility Australian breeding population A B Not applicable: past, current or future population declines are thought unlikely to exceed 20% in any 3-generation period Not applicable: EOO, AOO, habitat, locations or population not declining, population fluctuations not extreme C Not applicable: no continuing population decline or extreme fluctuations D Endangered: population 50–250 mature individuals E Not applicable: no population viability analysis undertaken Estimate Reliability 610 000 km2 stable high high Area of occupancy trend 3 km2 stable high high No. of mature individuals trend 100 stable medium high No. subpopulations 1 high No. locations 1 high 11.0 years medium Global population share <1% high Level of genetic exchange low low Australian breeding population Extent of occurrence trend Generation time © Birds Australia 2011 Published by CSIRO Publishing, http://www.publish.csiro.au/ Citation: Garnett ST, Szabo JK, Dutson G (2011) The Action Plan for Australian Birds 2010. CSIRO Publishing, Melbourne. rabbits have the potential to damage or completely destroy nesting habitat on Macquarie I., but the severity of this threat is unknown. Hamilton A (1894) Notes on a visit to Macquarie Island. Transactions and Proceedings of the New Zealand Institute 27, 559–579. Conservation objectives 1. Persistence of population Higgins PJ, Davies SJJF (Eds) (1996) Handbook of Australian, New Zealand and Antarctic Birds. Volume 3. Snipe to Pigeons. Oxford University Press, Melbourne. Information required 1. Population trends Rounsevell DE, Brothers NP (1984) The status of seabirds on Macquarie Island. In ‘Status and Conservation of the World’s Seabirds. ICBP Tech. Publ. 2’. (Eds JP Croxall, PGH Evans and RW Schreiber) pp. 587–592. ICBP, Cambridge, UK. Management actions required 1. Eradicate rats from Macquarie I. 2. Maintain quarantine for offshore stacks Bibliography BirdLife International (2011) ‘Species factsheet: Sterna vittata’. Retrieved 17 January, 2011 from <http://www.birdlife.org/>. © Birds Australia 2011 Published by CSIRO Publishing, http://www.publish.csiro.au/ Citation: Garnett ST, Szabo JK, Dutson G (2011) The Action Plan for Australian Birds 2010. CSIRO Publishing, Melbourne.