• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Taxonomic source(s)
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.
SACC. 2005 and updates. A classification of the bird species of South America. Available at: https://www.museum.lsu.edu/~Remsen/SACCBaseline.htm.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2022	Least Concern
2016	Endangered	A3c
2012	Endangered	A3c
2009	Least Concern
2008	Least Concern
2004	Least Concern
2000	Lower Risk/Least Concern
1994	Lower Risk/Least Concern
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)	465,000 km2	medium
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	10000-19999 mature individuals	poor	suspected	2021
Population trend	decreasing	-	suspected	2016-2026
Rate of change over the past 10 years/3 generations (longer of the two periods)	10-19%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	10-19%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	10-19%	-	-	-
Generation length	2.8 years	-	-	-
Number of subpopulations	1	-	-	-
Percentage of mature individuals in largest subpopulation	100%	-	-	-

Population justification: This is a poorly known species and no population estimates are available. It appears to be uncommon, and the population may be relatively small (Remsen and Sharpe 2020). Based on the paucity of records, it is precautionarily suspected that the population numbers between 10,000 and 19,999 mature individuals, but an accurate quantification of the population size is urgently needed.

Trend justification: The species is suspected to be in decline as forested habitat within the range is lost, degraded and fragmented.
Over the past ten years, roughly 6% of tree cover has been lost from the range, but since 2016 this rate has been increasing to 8% over ten years (Global Forest Watch 2021, using Hansen et al. [2013] data and methods disclosed therein). Given its high forest-dependency and its susceptibility to fragmentation and edge effects, population declines are likely faster than the rate of tree cover loss suggests, and are therefore here tentatively placed in the band 10-19% over ten years.

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

Country/Territory	IBA Name
Brazil	Ilha de Marajó
Brazil	Várzeas de Monte Alegre
Brazil	Várzeas do Médio Rio Amazonas

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Swamp	major	resident
Altitude	0 - 200 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Annual & perennial non-timber crops - Agro-industry farming	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture	Livestock farming & ranching - Agro-industry grazing, ranching or farming	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Ecosystem degradation, Ecosystem conversion

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Recommended citation
BirdLife International (2024) Species factsheet: Scaled Spinetail Cranioleuca muelleri. Downloaded from https://datazone.birdlife.org/species/factsheet/scaled-spinetail-cranioleuca-muelleri on 23/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 23/12/2024.