Fernwren Oreoscopus gutturalis


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 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
Species attributes

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 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 Paluma
Australia Wooroonooran
Australia Coastal Wet Tropics
Australia Daintree

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 300 - 1500 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, Species mortality

Recommended citation
BirdLife International (2023) Species factsheet: Oreoscopus gutturalis. Downloaded from http://datazone.birdlife.org/species/factsheet/fernwren-oreoscopus-gutturalis on 04/12/2023.
Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 04/12/2023.