Sao Tome oriole  (Oriolus crassirostris)

Classified as Vulnerable (VU) on the IUCN Red List 2007 (1).

Orioles are fairly large, boldly coloured, woodland and forest birds; only one species of oriole occurs on the island of São Tomé (3). Male São Tomé orioles have black heads and pale olive plumage on the upperparts, with darker wings and tail and greyish-white underparts. Touches of greyish-yellow decorate the back of the neck and the tip of the tail. Females, however, lack the bold black head and, like juveniles, have pale streaks across a darker breast (2) (3). Both sexes have a down-curved pink-red bill (2) (4), and are often detected by their loud ringing song (3)

Endemic to São Tomé, off the western equatorial coast of Africa. The São Tomé oriole occurs throughout the island except in the north-east (2).

The majority of the São Tomé oriole population occurs in lowland primary forest, but it also inhabits mid- to high-altitude forest and mature secondary forest (2) (5).

All orioles belonging to the Oriolidae family feed on insects and fruit, and most build deep, cup-shaped nests in the fork of a branch (4).

Following human colonisation, large areas of forest on São Tomé were cleared for cultivation, with 42 percent of the land being given to cocoa cultivation (5). During the 1970s, enormous quantities of pesticides were used in these cocoa plantations, greatly reducing the population of the oriole. The oriole had some chance to recover when, following a crash in cocoa prices in 1975, many cocoa plantations were abandoned and the land regenerated into secondary forest, providing suitable habitat for several endemic birds, including the São Tomé oriole (5). However, the oriole population has not fully recovered from these declines and is constantly threatened by the possibility of old plantations being brought back into production, or developed for different types of agriculture, which would almost certainly involve an increase in pesticide use (5).

The montane primary forest of the island is at immediate risk from encroaching agriculture, and any further loss of this vital habitat would seriously endanger the São Tomé oriole (5). Secondary forest on Sao Tome is also threatened by the development of agriculture and an increasing demand for timber (5). In addition, the development of roads on the island is opening up previously remote areas (2), increasing the chance of habitat loss and degradation.

The protection of the São Tomé oriole’s forest habitat appears to be critical to its long-term survival. A national park and a zona ecologica (ecological zone) have been proposed but await ratification (2) (6). The protection of lowland primary forest has been particularly recommended (2), but the protection of secondary forest, especially mature areas, is also required (5). Hopefully protected areas will be established before the São Tomé oriole becomes another victim of habitat loss.

View information on this species at the UNEP World Conservation Monitoring Centre.

For further information on the São Tomé oriole see:

• BirdLife International:
  www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=5887&m=0