Oriolus crassirostris 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Oriolidae

Scientific Name: Oriolus crassirostris
Species Authority: Hartlaub, 1857
Common Name(s):
English Sao Tome Oriole, São Tomé Oriole, Sao Tomé Oriole
French Loriot de São Tomé
Identification information: 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.

Assessment Information [top]

Red List Category & Criteria: Vulnerable D1 ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Taylor, J. & Butchart, S.
Contributor(s): Gascoigne, A., Melo, M. & Olmos, F.
Facilitator/Compiler(s): Ekstrom, J., Peet, N., Shutes, S., Starkey, M., Symes, A., Taylor, J.
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.

Previously published Red List assessments:
2008 Vulnerable (VU)
2004 Vulnerable (VU)
2000 Vulnerable (VU)
1996 Vulnerable (VU)
1994 Vulnerable (VU)
1988 Lower Risk/least concern (LR/lc)

Geographic Range [top]

Range Description: 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).

Countries occurrence:
Sao Tomé and Principe
Continuing decline in area of occupancy (AOO): No
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 480
Continuing decline in extent of occurrence (EOO): No
Extreme fluctuations in extent of occurrence (EOO): No
Number of Locations: 1
Continuing decline in number of locations: No
Extreme fluctuations in the number of locations: No
Upper elevation limit (metres): 1600
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: 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.
Current Population Trend: Stable
Additional data:
Number of mature individuals: 250-999 Continuing decline of mature individuals: No
Extreme fluctuations: No Population severely fragmented: No
No. of subpopulations: 1 Continuing decline in subpopulations: No
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: Yes
No. of individuals in largest subpopulation: 100

Habitat and Ecology [top]

Habitat and 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).

Systems: Terrestrial
Continuing decline in area, extent and/or quality of habitat: No
Generation Length (years): 3.7
Movement patterns: Not a Migrant

Threats [top]

Major Threat(s): 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 [top]

Conservation Actions: 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.

Citation: BirdLife International. 2012. Oriolus crassirostris. The IUCN Red List of Threatened Species 2012: e.T22706404A39413361. . Downloaded on 02 December 2015.
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