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Sao Tome Oriole Oriolus crassirostris

Justification
This species qualifies as Vulnerable because it is thought to have a small population, given the small area of suitable primary and mature secondary forest habitat within its range. Improved knowledge of its population and habitat requirements may result in its population estimate being revised upwards and its status being reviewed.

Taxonomic source(s)
Dowsett, R. J.; Forbes-Watson, A. D. 1993. Checklist of birds of the Afrotropical and Malagasy regions. Tauraco Press, Li
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Identification
20-22 cm. Forest-dwelling oriole. Male has black head, pale olive upperparts with darker wings and tail. Pale yellow upper and undertail-coverts with golden-yellow tips to tail feathers. Silky white remainder of underparts. Female lacks black head and has streaking across the breast. Juvenile similar to female but lacks yellow on tail and is more heavily streaked on underparts. Pink-red bill. Voice Melodic ou-huu, or hui-yiioouh, or hu-ou-hu.

Distribution and population
Oriolus crassirostris is endemic to São Tomé, São Tomé e Príncipe. It is widely distributed over much of the island, except the north-east, and is most abundant in the south-west and on the central massif, occurring everywhere at low densities, with old estimates of one to two birds per 25 ha (Atkinson et al. 1991, Christy and Clarke 1998).

Population justification
The population is estimated to number 250-999 mature 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 375-1,499 individuals in total, rounded here to 350-1,500 individuals.

Trend justification
The population is suspected to be stable as currently there are not thought to be any serious threats to the species's habitat.

Ecology
It is most abundant in primary forest (up to 1,600 m), but also occurs in undisturbed secondary forest. It occurs occasionally in dry forest in the north but is generally absent from cocoa plantations (Atkinson et al. 1991, Christy and Clarke 1998).

Threats
Historically, large areas of forest were cleared for cocoa and coffee plantations. Today, land privatisation is leading to an increase in the number of small farms and the clearance of trees and may be a threat to this species where it occurs in secondary habitats. Road developments along the east and west coasts are increasing access to previously remote areas (A. Gascoigne in litt. 2000). Construction for the country's developing oil industry, including the established idea of building 'free ports' (free economic zones) (M. Melo in litt. 2003), was seen as a potential threat to the species's habitat. However, prospecting on land was unsuccessful, and any construction is likely to be offshore (F. Olmos in litt. 2007).

Conservation Actions Underway
A new law providing for the gazetting of protected areas and the protection of threatened species (A. Gascoigne in litt. 2000, M. Melo in litt. 2003) has been ratified (F. Olmos in litt. 2007). Legislation for the creation of Obo National Park has also been ratified (F. Olmos in litt. 2007) and protection of primary forest as a zona ecologica has been proposed. Conservation Actions Proposed
Research its population size and distribution. Study its ecological requirements. Identify the key threats in order to produce conservation recommendations. Ensure legal protection of all remaining lowland primary forest. List it as a protected species under national law.

References
Atkinson, P.; Peet, N.; Alexander, J. 1991. The status and conservation of the endemic bird species of Sao Tomé and Príncipe, West Africa. Bird Conservation International 1: 255-282.

Christy, P.; Clarke, W. V. 1998. Guide des Oiseaux de Sao Tome et Principe. ECOFAC, Sao Tome.

Further web sources of information
Explore HBW Alive for further information on this species

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

Text account compilers
Ekstrom, J., Peet, N., Shutes, S., Starkey, M., Symes, A., Taylor, J.

Contributors
Gascoigne, A., Melo, M., Olmos, F.

IUCN Red List evaluators
Butchart, S., Taylor, J.

Recommended citation
BirdLife International (2014) Species factsheet: Oriolus crassirostris. Downloaded from http://www.birdlife.org on 30/08/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 30/08/2014.

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 - Sao Tome oriole (Oriolus crassirostris) 0

Key facts
Current IUCN Red List category Vulnerable
Family Oriolidae (Orioles and figbirds)
Species name author Hartlaub, 1857
Population size 250-999 mature individuals
Population trend Stable
Distribution size (breeding/resident) 480 km2
Country endemic? Yes
Links to further information
- Additional Information on this species