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Grey-headed Warbler Basileuterus griseiceps
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Justification
This species has a small range, with recent records from only seven locations. Significant areas of habitat remain, but it is likely to be declining rapidly in response to agricultural conversion, especially for shade coffee plantations. It is therefore listed as Endangered. However, if future studies reveal that it is able to survive in degraded habitats, it may qualify for downlisting to Vulnerable.

Taxonomic source(s)
SACC. 2006. A classification of the bird species of South America. Available at: #http://www.museum.lsu.edu/~Remsen/SACCBaseline.html#.

Identification
14 cm. Green-and-yellow warbler with grey head. Deep olive-green upperparts. Bright yellow underparts. Grey head, lightly streaked black on crown with distinctive white supraloral spot and white speckling on ear-coverts. Similar spp. Sympatric Basileuterus warblers have striped heads that do not contrast with upperparts. Voice Thin tseck and harsh thack or chack calls. Hints Often with mixed-species flocks.

Distribution and population
Basileuterus griseiceps occupies a restricted range in north-east Venezuela in the Turimiquire Massif (both in the Serranía de Turimiquire the west of the San Antonio valley and the Cordillera de Caripe to the east) on the borders of Sucre, Anzoategui and Monagas. Since the 1960s, it has been recorded on eight mountains: cerros La Pizarra, Turimiquire, El Guamal and Quiriquire ("Piedra 'e Mole'") in the in the Serranía de Turimiquire, and cerros Macanillal, Negro, El Gobierno and Cumbres de San Bonifacio in the Cordillera de Caripe (Colvee 1999, Azpúrua 2007, C. J. Sharpe in litt. 2011). Of these, it appears to be most numerous at Cerro Quiriquire ("Piedra 'e Mole'") (Azpúrua 2007, C. J. Sharpe in litt. 2011). On Cerro Negro, no more than ten small patches of suitable habitat remain (Boesman and Curson 1995, T. Brooks in litt. 1999). One patch was only 2 km2 and probably held 2-5 pairs (Boesman and Curson 1995). In 1993, one individual was observed on Cumbres de San Bonifacio (Boesman and Curson 1995).




Population justification
The population is estimated to number 2,500-9,999 individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for congeners or close relatives with a similar body size, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 1,667-6,666 mature individuals, rounded here to 1,500-7,000 mature individuals.

Trend justification
Although the species can still be found in patches of suitable habitat, ecosystem conversion and degradation are continuing unabated within the region, suggesting that populations are likely to be in decline, perhaps at a rate of 10-19% over ten years. Although it can occasionally be found in degraded forest, secondary forest and areas that have been previously cleared, it shows a strong preference for undisturbed humid forest with an intact understorey and is unlikely to persist successfully in the absence of primary forest (Sharpe 2008, C. J. Sharpe in litt. 2011).

Ecology
It inhabits dense understorey in the interior or edge of undisturbed subtropical forest and natural clearings (Boesman and Curson 1995). It apparently survives in disturbed forest if there is a dense understorey (of e.g. Heliconia) (Boesman and Curson 1995), and is thought to be fairly generalist in habitat requirements (Anon. 2007). However, a recent survey found that abundance was higher in less fragmented forest (Anon. 2007). The majority of specimens have been taken at 1,400-2,100 m, but it has been recorded up to 2,440 m, and as low as 1,200 m (Boesman and Curson 1995, Colvee 1999). Breeding seems to occur from May to July, with juveniles fledging in August (Boesman and Curson 1995). The only known nest was found in May in secondary vegetation around an old treefall gap (Hernández et al. 2009).


Threats
The entire Turumiquire Massif is under severe human pressure, which, through widespread clearance for agriculture and pasture, has resulted in extensive degradation of its montane forests. Even in El Guácharo National Park (incorporating Cerro Negro), there is forest clearance, burning and removal of the understorey for coffee (Boesman and Curson 1995). The slopes of Cerro Negro are largely bare, with the more obvious forest patches actually shade-coffee plantations (Boesman and Curson 1995). Shade-coffee cultivation safeguards some trees but destroys the understorey upon which this bird depends (Boesman and Curson 1995). There is conversion to coffee, mango, banana, and citrus plantations in the Serranía de Turumiquire, but extensive forested areas remain (Colvee 1999, C. J. Sharpe in litt. 2011). However, on Cumbres de San Bonifacio there are only two peaks above 1,400 m (Boesman and Curson 1995).


Conservation Actions Underway
Large areas of habitat persist within El Guácharo National Park, and the reserve has been expanded to include a further 500 km2 of largely undisturbed forest (Gabaldón 1992), although much of this is too low for this species (J. Pérez-Emán in litt. 2012). A programme of research into basic ecology and conservation needs is being carried out at the Central University of Venezuela (C. J. Sharpe in litt. 2011). It is considered nationally Endangered in Venezuela (Sharpe 2008).Conservation Actions Proposed
Survey historical localities and any significant tracts of forest remaining in the cordillera. Conduct studies of habitat requirements in order to determine levels of tolerance of disturbed habitats (Rodríguez and Rojas-Suárez 1995, Sharpe 2008). Increase the area of suitable habitat that has protected status, especially in the Turimiquire massif, where some of the most seriously threatened forests in Venezuela are found (Sharpe 2008) and where the species appears to be most common (C. J. Sharpe in litt. 2011, J. Pérez-Emán in litt. 2012).

References
Anon. 2007. Grey-headed Warbler and Venezuelan Flowerpiercer. Cotinga 27: 11.

Azpúrua, C. 2007. Distribución y hábitat de Basileuterus griseiceps y Diglossa venezuelensis, dos especies endémicas y amenazadas de la Cordillera Oriental de Venezuela. Report to Neotropical Bird Club Conservation Award. Caracas, Venezuela.

Boesman, P.; Curson, J. 1995. Grey-headed Warbler Basileuterus griseiceps in danger of extinction? Cotinga: 35-39.

Collar, N. J.; Gonzaga, L. P.; Krabbe, N.; Madroño Nieto, A.; Naranjo, L. G.; Parker, T. A.; Wege, D. C. 1992. Threatened birds of the Americas: the ICBP/IUCN Red Data Book. International Council for Bird Preservation, Cambridge, U.K.

Colvee, J. N. 1999. Observaciones preliminares sobre el estado actual del hábitat de cuatro especies de aves en la Serranía de Turimiquire, Edos. Monagas, Anzoátegui y Sucre de Venezuela.

Gabaldón, M. 1992. Parques Nacionales de Venezuela. Parques Nacionales y Conservación Ambiental, Caracas, Venezuela.

Hernández C. L. L.; Azpúrua, J. C.; Pérez-Emán, J. 2009. First description of the nest and egg of the Gray-headed Warbler (Basileuterus griseiceps). Ornitologia Neotropical 20: 311-314.

Rodríguez, J. P.; Rojas-Suárez, F. 1995. Libro Rojo de la fauna Venezolana. Provita, Caracas.

Sharpe, C.J. 2008. Chiví cabecigris Basileuterus griseiceps. In: Rodríguez, J.P. and Rojas-Suárez, F. (eds), Libro rojo de la fauna venezolana. Tercera Edición, pp. 153. Provita & Shell Venezuela, S.A., Caracas, Venezuela.

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.

Click here for more information about the Alliance for Zero Extinction (AZE)

Detailed species account from the Threatened birds of the Americas: the BirdLife International Red Data Book (BirdLife International 1992). Please note taxonomic treatment and IUCN Red List category may have changed since publication.

Detailed species account from the Threatened birds of the Americas: the BirdLife International Red Data Book (BirdLife International 1992). Please note, taxonomic treatment and IUCN Red List category may have changed since publication.

Explore HBW Alive for further information on this species

Recuento detallado de la especie tomado del libro Aves Amenazadas de las Americas, Libro Rojo de BirdLife International (BirdLife International 1992). Nota: la taxonomoía y la categoría de la Lista Roja de la UICN pudo haber cambiado desde esta publicación.

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Gilroy, J., Pople, R., Sharpe, C J

Contributors
Brooks, T., Sharpe, C J, Pérez-Emán, J.

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

Recommended citation
BirdLife International (2014) Species factsheet: Basileuterus griseiceps. Downloaded from http://www.birdlife.org on 02/08/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 02/08/2014.

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 - Grey-headed warbler (Basileuterus griseiceps) 0

Key facts
Current IUCN Red List category Endangered
Family Parulidae (New World warblers)
Species name author Sclater & Salvin, 1869
Population size 1500-7000 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 910 km2
Country endemic? Yes
Links to further information
- Additional Information on this species