Mountain Thornbill (Acanthiza katherina) | Details

Mountain Thornbill Acanthiza katherina

Current view: Data table and detailed info

Taxonomy

Taxonomic source(s)
Christidis, L. and Boles, W.E. 2008. Systematics and Taxonomy of Australian Birds. CSIRO Publishing, Collingwood, Australia.
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.

IUCN Red List criteria met and history

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	A2bc+3c+4bc

Red List history

Year	Category	Criteria
2022	Vulnerable	A2bc+3c+4bc
2016	Least Concern
2012	Least Concern
2009	Least Concern
2008	Least Concern
2004	Least Concern
2000	Lower Risk/Least Concern
1996	Lower Risk/Conservation Dependent
1994	Lower Risk/Conservation Dependent
1988	Lower Risk/Least Concern

Species attributes

Migratory status	not a migrant	Forest dependency	high
Land-mass type		Average mass	-

Range

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	18,600 km²
Severely fragmented?	no	-

Population

	Estimate	Data quality	Derivation	Year of estimate
Population size	380000-1770000, 820000 mature individuals	medium	estimated	2020
Population trend	decreasing	-	estimated	2012-2022
Rate of change over the past 10 years/3 generations (longer of the two periods)	40-49%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	40-49%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	40-49%	-	-	-
Generation length	3.14 years	-	-	-
Number of subpopulations	3-4	-	-	-
Percentage of mature individuals in largest subpopulation	1-89%	-	-	-

Population justification: The abundance of Mountain Thornbills is calculated from the density and distribution of birds using data from standardised transect surveys along elevational gradients and the area of climatically suitable habitat at different altitudes in 2016 (Williams et al. 2010a, 2021); the population thus numbers 380,000-1,770,000 mature individuals, with a best estimate of 820,000.

Trend justification: There appears to have been a substantial decline in population size in the last three generations, as predicted by climate change modelling (Williams et al. 2003). Annual monitoring undertaken between 2000–2016 (1,970 plots, 62 different locations, at 0–1,500 m altitude) revealed a highly significant 46.3% decline in the total population over the 10 years to 2016 from an estimated 1.53 million to 820,000 individuals (Williams & de la Fuente 2021). Numbers increased from 2000–2008 at both mid-altitudes (450–850 m) and higher altitudes (>850 m) before commencing a rapid decline, again as expected from models. This so-called 'escalator to extinction' effect is predicted to cause an ongoing rate of decline of 40-49% every ten years.

Country/territory distribution

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Australia	extant	native	yes

Important Bird and Biodiversity Areas (IBA)

Country/Territory	IBA Name
Australia	Daintree
Australia	Paluma
Australia	Wooroonooran

Habitats & altitude

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Moist Lowland	major	resident
Forest	Subtropical/Tropical Moist Montane	suitable	resident
Altitude	450 - 1600 m	Occasional altitudinal limits

Threats & impact

Threat (level 1)

Threat (level 2)

Impact and Stresses

Climate change & severe weather

Habitat shifting & alteration

Timing

Scope

Severity

Impact

Ongoing

Whole (>90%)

Rapid Declines

High Impact: 8

Stresses
Ecosystem degradation