• Summary
• Text account
• Data table and detailed info
• Range map
• Resources

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.

Red List criteria met

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

Red List history

Year	Category	Criteria
2022	Endangered	A2bc+3c+4bc
2016	Least Concern
2012	Least Concern
2009	Least Concern
2008	Least Concern
2004	Least Concern
2000	Lower Risk/Least Concern
1994	Lower Risk/Near Threatened
1988	Lower Risk/Least Concern

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

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	23,000 km2	medium
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	450000-1000000, 660000 mature individuals	medium	estimated	2016
Population trend	decreasing	-	estimated	2013-2023
Rate of change over the past 10 years/3 generations (longer of the two periods)	50-60%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	50-60%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	50-60%	-	-	-
Generation length	3.1 years	-	-	-
Number of subpopulations	3-4	-	-	-
Percentage of mature individuals in largest subpopulation	1-89%	-	-	-

Population justification: The abundance of Fernwrens 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. 2021). The population is estimated at 450,000-1,000,000 mature individuals, with a best estimate of 660,000 mature individuals.

Trend justification: There appears to have been a substantial decline in population size in the last ten years, as predicted from climate change modelling (Williams et al. 2003). Annual monitoring undertaken 2000–2016 (1,970 plots, 62 different locations, 0–1,500 m altitude) revealed a highly significant decline of 57% in the total population over the ten years to 2016 from an estimated 1.54 million to 660,000 individuals. There were never many at low altitudes (<450 m), and the species appears to have disappeared at some lower sites (360–400 m) where it was present in the late 1990s (J. Grant unpublished, in Williams et al. 2021). Numbers increased at medium altitudes (450–850 m) until 2006 but declined after 2008-2012. At higher altitudes (>850 m), which has the smallest area, numbers rose until 2006 and stayed steady until monitoring stopped in 2016 (Williams & de la Fuente 2021). However, ongoing climate change is suspected to have the same impact on higher altitudes as it did at medium altitudes in the next three generations and so the rate of decline is broadly estimated to be the same.

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

Country/Territory	IBA Name
Australia	Coastal Wet Tropics
Australia	Daintree
Australia	Paluma
Australia	Wooroonooran

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Moist Lowland	major	resident
Forest	Subtropical/Tropical Moist Montane	suitable	resident
Altitude	300 - 1500 m	Occasional altitudinal limits

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, Species mortality

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Recommended citation
BirdLife International (2025) Species factsheet: Fernwren Oreoscopus gutturalis. Downloaded from https://datazone.birdlife.org/species/factsheet/fernwren-oreoscopus-gutturalis on 13/01/2025.
Recommended citation for factsheets for more than one species: BirdLife International (2025) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 13/01/2025.