Download Brown Thornbill (King Island) - Australia`s Threatened Birds

Subspecies Conservation Summary
Brown Thornbill (King Island)
Acanthiza pusilla archibaldi Mathews, 1910
Acanthizidae
Conservation status
Critically Endangered D
Reasons for listing
Population probably <50 mature individuals
Status 2000
Critically Endangered D
Status 1990
Critically Endangered D
Taxonomy
The other 4 subspecies in eastern Australia, Tasmania
and Kangaroo I. are all Least Concern, as is the species
Taxonomic uniqueness: medium (14 genera/family, 12
species/genus, 5 subspecies/species)
Range
Endemic to King I., Tasmania (Boles 1983). Since the
discovery of the subspecies, there are only about a dozen
records (Department of Sustainability, Environment,
Water, Population and Communities 2011). They were
recorded in Pegarah Forestry Reserve in 1968 (Green and
McGarvie 1971), at Loorana in 1971 (McGarvie and
Templeton 1974) and not until 2002 in Pegarah again
(S. Lloyd pers. comm.).
Abundance
Extraordinarily scarce. There have never been many
records of this species on King I. so there are assumed to
be no more than 50 mature individuals.
Ecology
The subspecies evidently persisted in dense mixed scrub
in the 1 remaining forest fragment on the island until
1968 (Green and McGarvie 1971) and was captured in a
garden adjacent to open farmland in 1971 (McGarvie and
Templeton 1974). The record in March 2002 was in wet
forest dominated by Tasmanian Blue Gum Eucalyptus
globulus, with an understorey of Swamp Paperbark Melaleuca ericifolia, Rough Dogwood Pomaderris apetala and
Goldenwood Monotoca glauca (Department of Sustainability Environment Water Population and Communities
2011). Its ecology is probably similar to that of the Tasmanian subspecies A. p. diemenensis (Higgins and Peter
2002). A generation length of 5.7 years (BirdLife International 2011) is derived from an age at first breeding of 1.0
years (Higgins and Peter 2002) and maximum longevity
in the wild of 17.6 years (Australian Bird and Bat Banding
Scheme).
Threats
The principal threat is currently loss of remaining habitat,
primarily from fire but also from clearing. Any remain-
ing population will also be vulnerable to minor changes
in mortality, such as from predation by feral cats Felis
catus, Black Rat Rattus rattus or a range of native
mammals, birds or reptiles, tick infestation (Schodde and
Mason 1999) or inbreeding. Historically land clearance
has removed most of the habitat of the species and its
scarcity is probably an extinction debt from that process;
extirpated subpopulations can no longer be replaced by
natural dispersal from other sites.
Conservation objectives
1. Secure existing populations
2. Increase the number of individuals and
subpopulations
Information required
1. Location of birds
2. Demographic trends including population size,
density, trends, survival, productivity and
movements
3. Ecological resource bottlenecks such as habitat
structure and food availability
Management actions required
1. Search for remaining birds
2. Develop and implement fast-response fire protection
plans for any sites discovered
3. Work with neighbours to any sites found to reduce
the incidence of fire
4. Monitor number and productivity of thornbill
5. Conduct basic demographic and ecological research
6. Identify other sites with potential habitat
7. If appropriate undertake cross-fostering experiments,
food supplementation, habitat restoration and
translocation
8. Increase community awareness of the thornbill
Bibliography
BirdLife International (2011) ‘Species factsheet: Acanthiza
pusilla’. 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.
Current eligibility against IUCN Red List Criteria
IUCN
category
A
Criteria eligibility
Not applicable: past, current or future population
declines are thought unlikely to exceed 20% in any
3-generation period
B
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
E
Critically Endangered: population <50 mature
individuals
Not applicable: no population viability analysis
undertaken
IUCN Red List assessment data
Estimate
Reliability
Extent of occurrence
trend
5 km2
stable
low
low
Area of occupancy
trend
5 km2
stable
low
low
No. of mature individuals
trend
50
stable
low
low
No. subpopulations
1
low
No. locations
1
low
5.7 years
high
100%
high
Generation time
Global population share
Boles WE (1983) A taxonomic revision of the Brown Thornbill
Acanthiza pusilla (Shaw) 1790 with description of a new subspecies. Emu 83, 51–58.
Higgins PJ, Peter JM (Eds) (2002) Handbook of Australian, New
Zealand and Antarctic Birds. Volume 6: Pardalotes to Spangled Drongo. Oxford University Press, Melbourne.
Department of Sustainability Environment Water Population
and Communities (2011) Acanthiza pusilla archibaldi. In
‘Species Profile and Threats Database’. Department of Sustainability, Environment, Water, Population and Communities, Canberra. Retrieved 24 February, 2011 from <http://
www.environment.gov.au/sprat>.
McGarvie AM, Templeton MT (1974) Additions to the birds of
King Island, Bass Strait. Emu 74, 91–96.
Green R, McGarvie AM (1971) The birds of King Island. Records
of the Queen Victoria Museum 40, 1– 42.
Schodde R, Mason IJ (1999) The Directory of Australian Birds:
Passerines. CSIRO Publishing, Melbourne.
Comments received from
Nigel Burgess, Richard Donaghey, Mark Holdsworth,
Sarah Lloyd, Eric Woehler
© 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.