• 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
2023	Least Concern
2016	Near Threatened	A2c+3c+4c
2012	Near Threatened	A2c+3c+4c
2008	Near Threatened	A2c; A3c; A4c
2004	Near Threatened
2000	Lower Risk/Near Threatened
1994	Lower Risk/Near Threatened
1988	Near Threatened

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

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	1,043,000 km2	medium
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	unknown	-	-	-
Population trend	decreasing	poor	inferred	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	2.29 years	-	-	-
Number of subpopulations	2-100	-	-	-
Percentage of mature individuals in largest subpopulation	1-89%	-	-	-

Population justification: The global population size has not been quantified, but this species is described as uncommon and patchily distributed, though it may potentially be under-recorded (Stotz et al. 1996, B. Phalan in litt. 2023).

Trend justification:

The population trend has not been investigated, but the species has reportedly undergone declines and local extinctions, including in parts of its distribution in Paraguay as well as in Bahia, Rio de Janeiro, Minas Gerais, Espírito Santo and Paraná, Brazil (B. Phalan in litt. 2023, eBird 2023). Population declines are attributed to the loss, degradation and fragmentation of forests within the range.
Over ten years, up to 9% of tree cover is lost within the entire potential range (Global Forest Watch 2022, using Hansen et al. [2013] data and methods disclosed therein), primarily due to agricultural conversion, urbanisation, industrialisation and associated road-building (Fitzpatrick 2020). Although it may incur some tolerance to degradation given previous records in Brazil at degraded sites, the species is strongly forest-dependent and sensitive to habitat loss and degradation (Aleixo and Galetti 1997, B. Phalan in litt. 2023). Population declines are therefore tentatively placed in the band 10-19% over ten years, but an accurate quantification is urgently required.

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

Country/Territory	IBA Name
Argentina	Parque Nacional Iguazú y alrededores
Argentina	Parque Provincial Guardaparque Horacio Foerster
Argentina	Parque Provincial Piñalito y alrededores
Argentina	Parque Provincial Salto Encantado del Valle del Cuñá-Pirú y alrededores
Argentina	Parque Provincial Urugua-í
Argentina	Parque Provincial Uruzú y Reserva Forestal San Jorge
Argentina	Reserva de la Biósfera Yabotí
Argentina	Reserva Privada Yaguaroundí
Argentina	San Antonio
Argentina	San Pedro
Paraguay	Bosque Mbaracayú
Paraguay	Estancia Itabó
Paraguay	Ka'aguy Rory
Paraguay	Parque Nacional Caazapá
Paraguay	Parque Nacional San Rafael
Paraguay	Paso Curuzú
Paraguay	Serranías de San Joaquín
Paraguay	Tapyta
Paraguay	Ypeti

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Artificial/Terrestrial	Subtropical/Tropical Heavily Degraded Former Forest	suitable	resident
Forest	Subtropical/Tropical Moist Lowland	major	resident
Altitude	0 - 840 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		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture	Wood & pulp plantations - Agro-industry plantations	Timing		Scope		Severity		Impact
		Past, Likely to Return		Majority (50-90%)		Slow, Significant Declines		Past Impact
		Stresses Ecosystem degradation, Ecosystem conversion
Biological resource use	Logging & wood harvesting - Unintentional effects: (large scale) [harvest]	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Energy production & mining	Mining & quarrying	Timing		Scope		Severity		Impact
		Past, Likely to Return		Majority (50-90%)		Slow, Significant Declines		Past Impact
		Stresses Ecosystem degradation, Ecosystem conversion
Residential & commercial development	Commercial & industrial areas	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Residential & commercial development	Housing & urban areas	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Transportation & service corridors	Roads & railroads	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion

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Recommended citation
BirdLife International (2024) Species factsheet: Bay-ringed Tyrannulet Phylloscartes sylviolus. Downloaded from https://datazone.birdlife.org/species/factsheet/bay-ringed-tyrannulet-phylloscartes-sylviolus on 23/11/2024.
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 23/11/2024.