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

Justification of Red List category
This species has a large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km² combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is unknown, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

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.

Phylloscartes sylviolus is scarce in south-east Brazil, north-east Argentina and east Paraguay. It has disappeared from many previously occupied sites; its strongholds are now in Misiones, Argentina and the Serra do Mar, Brazil (B. Phalan in litt. 2023, eBird 2023).

It principally inhabits forest canopy in lowland Atlantic forest (Fitzpatrick 2020), but is encountered in small groups at forest edge, and has been observed in palms and dead trees adjacent to forest (Clay et al. 1998). At one site in Brazil, it has been recorded only in edges, secondary and selectively logged forest (Aleixo and Galetti 1997). 

Agricultural conversion and deforestation for mining and plantation production historically threatened its habitat (Fearnside 1996). Current key threats are urbanisation, industrialisation, agricultural expansion, colonisation and associated road-building (Dinerstein et al. 1995, Fitzpatrick 2020).

Conservation Actions Underway
It occurs in several protected areas, including Iguaçu National Park and Mata dos Godoy and Intervales State Parks, Brazil; Iguazú National Park in Argentina; and Estancia Itabó Private Nature Reserve, Mbaracayú Forest Nature Reserve and Caaguazú and San Rafael National Parks in Paraguay (del Hoyo et al. 2004). It is listed as Vulnerable at the national level in Argentina (MAyDS and AA 2017), and as Least Concern in Brazil (Silveira et al. 2022).

Conservation Actions Proposed
Quantify the population size and density. Quantify the population trend. Study its ecology and its ability to persist in degraded and fragmented habitats. Effectively protect areas where the species occurs.

Text account compilers
Hermes, C., Fernando, E.

Contributors
Babarskas, M., Capper, D., Clay, R.P., Lima, D.M., O'Brien, A., Phalan, B., Sharpe, C.J. & Symes, A.

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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 23/12/2024.
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.