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Choco Vireo Vireo masteri
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This species has a small population, a small range and is known with certainty from just three separate areas. Its range and population are likely to be declining because of continuing habitat destruction. Recent searches in suitable habitat in intermediate areas have failed to find this species, and it is therefore classified as Endangered.

Taxonomic source(s)
SACC. 2006. A classification of the bird species of South America. Available at:

Vireo sp. Collar et al. (1994), Vireo sp. sp. Collar et al. (1994)

10 cm. Small, olive-and-yellow, warbler-like bird. Olive-green above with broad, prominent yellow supercilium contrasting with greyish-olive crown and dark eye-stripe. Dark brown remiges with olive-green edges. Broad, creamy, double wing-bar. Creamy-white below, with yellow breast, flanks and vent. Blackish maxilla, pale mandible. Bright bluish legs. Similar spp. Brown-capped Vireo V. leucophrys has brown upperparts and lacks wing-bars. Rufous-rumped Antwren Terenura callinota has rufous rump and longer tail. Voice Variable, high-pitched, warbling song 6-20 notes over 1-3 seconds. Contact call brief dry chip, and disturbance note a nasal zhree-zhree-zhree, most similar to Red-eyed Vireo Vireo olivaceus in quality.

Distribution and population
Vireo masteri is restricted to the Pacific slope of the West Andes of Colombia and north-western Ecuador. It is known from half a dozen locations in Colombia (Alto de Pisones, Risaralda, and two in the Junín area, Nariño [Salaman 1994, Salaman and Stiles 1996, Salaman in litt. 1999, 2000, 2003]), and Ecuador (Alto Tambo [Jahn et al. 2007] and El Cristal, Esmeraldas, and the Maphi road, Pichincha [D. Brinkhuizen in litt. 2010]). 

Population justification
Its potential global population was estimated to be as high as 78,000 ±7,000 mature individuals based on estimates of the area of forest cover within its range. However, the two occupied areas in Colombia are 520 km apart, and although the species may occur in appropriate habitat in between these sites (Salaman and Stiles 1996, Salaman in litt. 1999, 2000, 2003, Renjifo et al. 2002), searches of the intervening area have completely failed to find the species, despite excellent knowledge of its vocalizations and its reliable response to playback (Salaman in litt. 1999, 2000, 2003). Therefore, a precautionary population size estimate was made of 15,600 ±1,400 mature individuals based upon a figure of 20% occupancy within the Extent of Occurrence (Jahn et al. 2007). The total population is estimated to number 20,000-25,000 individuals, based on population density data from Ecuador extrapolated over the species's known range. Population size is thought to be declining owing to loss and fragmentation of its habitat.

Trend justification
The rate of habitat loss within occupied cloud-forest habitat types is unknown, but the species is suspected to be declining at a slow rate.

In Colombia, it has only been recorded in wet (>5,000 mm per year) primary cloud-forest, usually on steeply sloping terrain with a rather broken canopy and natural tree-fall gaps (Salaman and Stiles 1996, Renjifo et al. 2002). Areas with abundant palms, epiphytes, ferns and moss between 1,100 and 1,600 m are favoured (Salaman and Stiles 1996, Salaman in litt. 1999, 2000, 2003). In Ecuador, the species has been found in a wider range of habitats, including wet primary forest on level ground and steep slopes, as well as forest edges bordering pastures, roads, and railways, and re-growth of intensively logged forest, between 800 and 1,500m (Jahn et al. 2007). In Colombia, up to five territorial singing males were encountered per kilometre of transect (Salaman in litt. 1999, 2000, 2003), whilst densities of 15.9 ±1.4 territories/km2 were estimated within suitable habitat in Ecuador (Jahn et al. 2007). Encountered in pairs, individuals and family parties, it primarily forages in the canopy, or occasionally lower down in clearings and tree-falls. It is often found accompanying mixed-species flocks (Salaman and Stiles 1996, Salaman in litt. 1999, 2000, 2003, Jahn et al. 2007). Breeding takes place during the dry season, from June to October, and adults have been seen feeding juveniles in August (Salaman and Stiles 1996). It is a very active forager, feeding on invertebrates (Salaman and Stiles 1996).

The Chocó region has long been a source of timber, but logging has intensified since the mid-1970s. Plans to colonise and develop the region are progressing through infrastructural improvement, particularly the rapid expansion of the road network, and are increasing the impact of logging, small-scale agriculture and gold mining (Salaman 1994, Wege and Long 1995, Salaman and Stiles 1996). Coca cultivation is a growing problem at lower altitudes (Salaman in litt. 1999, 2000, 2003). In Colombia, Río Ñambi Community Nature Reserve is threatened by logging, and disputes over land ownership, but the population is currently secure (Salaman in litt. 1999, 2000, 2003). Alto de Pisones remains unprotected and largely deforested (Salaman in litt. 1999, 2000, 2003). In Ecuador, the species is presumed to occur within the Cotacachi-Cayapas Ecological Reserve (243,638 ha; altitudinal range 80-4,900 m), Esmeraldas. However, the reserve is threatened by incursions from local communities, as well as colonists from Colombia and other regions of Ecuador (Jahn et al. 2007, Jahn in litt. 2007). Forests around Alto Tambo are largely unprotected and threatened by clearance for cattle ranching and forestry projects (Jahn et al. 2007, Jahn in litt. 2007).

Conservation Actions Underway
In Colombia, it is protected in the Las Tangaras Nature Reserve, Chocó and El Pangan and Río Ñambí Community Nature Reserves, Nariño (Salaman and Stiles 1996, Strewe in litt. 1999, Salaman in litt. 1999, 2000, 2003, 2012). Although the population at Alto Pisones remains unprotected, the area may be included in the proposed Caramanta National Park, a management plan for which is in preparation (Stiles 1998). In Ecuador, populations may exist within the Cotacachi-Cayapas Ecological Reserve (Jahn et al. 2007). Some of the occupied area at Alto Tambo is protected as an extractive reserve by Fundación para el Desarrollo Forestal, indicating that the suitability of the area for this species may depend on future forestry practices (intensive vs. selective harvesting schemes; natural-forest management vs. plantations of exotic timber tree species) (Jahn et al. 2007). Conservation Actions Proposed
Survey the montane forests between the known locations in both Colombia and Ecuador. Surveys should aim to determine presence and population densities across the region, with emphasis on existing reserves, e.g. Cotacachi-Cayapas Ecological Reserve. Protect the population at Alto de Pisones effectively and enforce protection of Río Ñambi Community Nature Reserve (Salaman in litt. 1999, 2000, 2003). Ensure future protection of Cotacachi-Cayapas Ecological Reserve (Jahn et al. 2007). Encourage sympathetic management of extractive forest reserves close to Alto Tambo, owned by Fundación para el Desarrollo Forestal (Jahn et al. 2007).

Cárdenas, A. 2007. Análisis multitemporal de cobertura vegetal y uso del suelo para la Ventana Binacional Ecuador, período 1998 - 2007, Proyecto "Diseño del SIMSA - CCCM".

Jahn, O. in press. Bird communities of the Ecuadorian Chocó: a case study for conservation. Bonner Zoologische Monographien 56.

Jahn, O.; Palacois, B.; Valenzuela, P. M. 2007. Ecology, population and conservation status of the Chocó Vireo Vireo masteri, a species new to Ecuador. Bulletin of the British Ornithologists' Club 127(2): 161-166.

Renjifo, L. M.; Franco-Maya, A. M.; Amaya-Espinel, J. D.; Kattan, G. H.; López-Lans, B. 2002. Libro rojo de aves de Colombia. Instituto de Investigación de Recursos Biológicos Alexander von Humboldt y Ministerio del Medio Ambiente, Bogot, Colombia.

Salaman, P. G. W. 1994. Surveys and conservation of biodiversity in the Chocó, south-west Colombia. BirdLife International, Cambridge, U.K.

Salaman, P. G. W.; Stiles, F. G. 1996. A distinctive new species of vireo (Passeriformes: Vireonidae) from the Western Andes of Colombia. Ibis 138: 610-619.

Stiles, F. G. 1998. Notes on the biology of two threatened species of Bangsia tanagers in northwestern Colombia. Bulletin of the British Ornithologists' Club 118: 25-31.

Wege, D. C.; Long, A. J. 1995. Key Areas for threatened birds in the Neotropics. BirdLife International, Cambridge, U.K.

WWF/IUCN. 1994-1997. Centres of plant diversity. A guide and strategy for their conservation. IUCN, Cambridge, UK.

Further web sources of information
Alliance for Zero Extinction (AZE) species/site profile. This species has been identified as an AZE trigger due to its IUCN Red List status and limited range.

Text account compilers
Benstead, P., Gilroy, J., O'Brien, A., Sharpe, C J

Jahn, O., Salaman, P., Strewe, R., Valenzuela, P., Brinkhuizen, D.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2014) Species factsheet: Vireo masteri. Downloaded from on 24/04/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from on 24/04/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Choco vireo (Vireo masteri) 0

Key facts
Current IUCN Red List category Endangered
Family Vireonidae (Vireos and allies)
Species name author Salaman & Stiles, 1996
Population size 15423-15777 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 3,100 km2
Country endemic? No
Links to further information
- Additional Information on this species