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

Justification of Red List category
This species has an extremely 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 has not been quantified, 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 generally described as rare and patchily distributed (Stotz et al. 1996, Fitzpatrick and Kirwan 2023). It however appears to be common locally, including in Sipaliwini (Suriname) and in Bolivia, where substantial populations remain (O. Ottema in litt. 2020, Fitzpatrick and Kirwan 2023). Density estimates range from 2.2 individuals/km² to more than 20 individuals/km² (Fitzpatrick and Kirwan 2023, Marini et al. 2023). Given its overall rarity, localised distribution and strict habitat requirements, an extrapolation of the population based on these estimates is not feasible (Marini et al. 2023). Nevertheless, the global population is likely large.
The species is restricted to specific habitat within the Cerrado biome, open humid grassy habitats, which are easily converted to agriculture (A. Lees in litt. 2024, E.R. Luiz in litt. 2024). Due to the loss of habitat, the population is suspected to be declining.

Trend justification
The species likely used to be more widespread, but is restricted to specific habitat within the Cerrado biome, open humid grassy habitats, which are easily converted to agriculture (A. Lees in litt. 2024, E.R. Luiz in litt. 2024). It is thought to be undergoing slow declines as a consequence of the ongoing conversion and degradation of its grassland habitat (Collar et al. 1992, Fitzpatrick and Kirwan 2023). The rate of reduction is unknown, and the rate of habitat loss relevant for the species has also not been quantified.

Euscarthmus rufomarginatus occurs locally in grasslands from south Suriname through Brazil and Bolivia to north-east Paraguay. The extent of occurrence is therefore very large, and despite only being present patchily it is thought to occupy an area that greatly exceeds the range size criteria.

It occurs in pristine, shrubby campo and campo cerrado, and feeds on insects and fruit. It colonises recently burned areas (Lopes et al. 2010). Young birds were being fed by the parents in January and February at Serra Geral do Tocantins Ecological Station (Lopes et al. 2010). Stomach contents of these individuals contained almost equal proportions of small fruits and insects (Lopes et al. 2010).

Habitat loss in the cerrado is probably the major factor explaining its current rarity. By 1993, two-thirds of the region had been heavily or moderately altered, with most of the destruction having occurred since 1950 (Cavalcanti 1999, Conservation International 1999). There has been extensive conversion to agriculture for livestock farming, Eucalyptus plantations, soybeans and exportable crops, encouraged by government land reform in Brazil (Stotz et al. 1996, Parker and Willis 1997, Marini et al. 2023). However, unlike many other cerrado birds it is not restricted to the upland cerrado of the Planalto Central, but also occurs in savanna enclaves in the Amazon which are under less pressure from large-scale habitat conversion.

Conservation Actions Underway
It occurs in several protected areas across its range, including Campos Amazônicos, Chapada Diamantina, Chapada Guimarães, Emas, Brasília, Grande Sertão Veredas and Nascentes do Rio Parnaíba National Parks (Brazil), as well as Noel Kempff Mercado National Park (Bolivia) and Sipaliwini Nature Reserve (Suriname). It is included in a multi-species action plan for birds of the Caatinga (ICMBio 2019).

Conservation Actions Proposed
Survey areas of suitable habitat to locate additional populations, obtain population density estimates and quantify the total population size and trend. Study the species' ecology and population structure. Assess the impact of threats and possible reasons for its rarity. Monitor the population trend. Monitor rates of habitat loss.
Expand the area of suitable habitat that has protected status. Restrict monocultures and plantations to already cleared land in order to avoid conversion of pristine cerrado and campos. Remove incentives encouraging habitat loss, especially the planting of Eucalyptus trees on grasslands.

11 cm. Small tyrannulet with contrasting throat and chest. Dull brown above with indistinct, pale buffy supraloral and short eyebrow. Long tail and wings duskier, with two dull buff wing-bars. White throat. Warm olivaceous-buff chest and flanks. Rest of underparts yellowish. Slender grey bill with flesh mandible. Similar spp. Female Bearded Tachuri Polystictus pectoralis has shorter bill and tail, and shows less contrast between throat and breast. Tawny-crowned Pygmy-tyrant E. meloryphus has much plainer wings and paler underparts. Voice Fast, musical and slurry tchip chip chip-tchrrrrrui.

Text account compilers
Martin, R., Hermes, C.

Contributors
Capper, D., Harding, M., Mayer, S., Minns, J., Olmos, F., Ottema, O., Pacheco, J.F., Sharpe, C.J., Silva, R., Stuart, T., Symes, A., Luiz, É.R., Lees, A., Clay, R.P. & Subirá, R.

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Recommended citation
BirdLife International (2024) Species factsheet: Rufous-sided Pygmy-tyrant Euscarthmus rufomarginatus. Downloaded from https://datazone.birdlife.org/species/factsheet/rufous-sided-pygmy-tyrant-euscarthmus-rufomarginatus 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.