Download Antarctic Tern (New Zealand) - Australia`s Threatened Birds

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.