Mountain Thornbill Acanthiza katherina


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 -

Estimate Data quality
Extent of Occurrence (breeding/resident) 18,600 km2
Severely fragmented? no -
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
Ecosystem degradation
Climate change & severe weather Temperature extremes Timing Scope Severity Impact
Ongoing Whole (>90%) Rapid Declines High Impact: 8
Ecosystem degradation, Species mortality

Recommended citation
BirdLife International (2024) Species factsheet: Acanthiza katherina. Downloaded from on 26/02/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from on 26/02/2024.