• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Justification of Red List category
This species is classified as Endangered, as it exists within a very small range, and is suspected to be undergoing a population decline owing to intense hunting pressure.

Population justification
Based on transect surveys and distribution modelling, the population size has been estimated at 3,893 - 5,497 individuals (Cavalho 2015), which equates to approximately 2,600 - 3,700 mature individuals.

Trend justification
The population is inferred to be declining owing to hunting pressure. The species is large and tame and a prime target for hunters, and has disappeared or become scarce in easily accessible areas (Carvalho, 2015). 

Columba thomensis is endemic to São Tomé, São Tomé e Príncipe, where it is now nearly absent from the most populated and drier northeast of the island (Soares et al., 2020). Its range includes Chamico in the north-west, the regions of Lagoa Amelia, Zampalma, Nova Ceilão and Bombaím in the central massif and Formoso Pequeno southwards along the valley of the Io Grande and Ana Chaves rivers. In the south-west, it extends into the lowlands along the valleys of the Xufexufe and Quija rivers. In the south-east, it occurs west of Agua Izé and on the isolated peak of Maria Fernandes, north of São João dos Angolares (Atkinson et al. 1991, Christy and Clarke 1998). The species usually occurs at low densities, even though it sometimes concentrates around fruiting trees, with a maximum of 18 birds observed in two 1 km transects after the breeding season in a core area of high altitude forest near the Pico of São Tomé (Carvalho, 2015). The global population has been estimated at 3,893 - 5,497 individuals, which roughly equates to 2,600 - 3,700 mature individuals (Carvalho, 2015). Hunting is suspected to be causing population declines across the range, pushing the species into more inaccessible areas, (Carvalho, 2015; Soares et al., 2020). It is estimated to be restricted to 299 km² of suitable habitat (based on Soares et al., 2020). 

It is most common in primary forest, but also occurs in mature secondary forest and more occasionally in cultivated areas at forest edges (Carvalho et al., 2015). The diet consists primarily of fruit, and the species appears to make seasonal movements in response to fruit availability (Jones & Tye, 2006; Carvalho et al., 2015; Coelho, 2016).

Hunting is the key threat to this species, particularly in the most accessible areas of forest. This is the largest pigeon on the island and it is also very tame (Jones & Tye, 2006). Opportunistic hunting for food in rural communities is thought to be more of an issue than commercial hunting. Significant numbers of birds may be taken at a time, for example a single hunter was observed to kill nine birds in one session. The current distribution of species is thought to be determined by hunting pressures (Carvalho et al., 2015). Historically, large areas of forest were cleared for coffee and cocoa plantations. Many of these have been abandoned, resulting now in large extents of secondary forest. Today, the forest is threatened by timber extraction and agricultural expansion and intensification, particularly in the north (Atkinson et al. 1991, Oyonon et al. 2014). 

Conservation Actions Underway
An important part of this species's range falls within the protected São Tomé Obo Natural Park. It is also protected from hunting in protected areas and between October and February. There are ongoing projects supporting biodiversity conservation, protected areas management, and sustainable management of forests in Sao Tome and Principe, for example the ECOFAC6 initiative 2018-2022 (BirdLife International, 2019). 

Conservation Actions Proposed
Research its ecological requirements, namely concerning breeding and feeding. Monitor hunting pressure, population size and trends. Ensure the implementation of existing environmental laws. Implement policies and raise awareness to reduce hunting pressure towards full protection against hunting.

37-40 cm. Large, very dark pigeon. Dark slate-grey head. Black centred, lanceolate neck feathers with blue-grey tips. Deep purple tinged neck, maroon mantle, slaty-black back and rump and dark brown uppertail-coverts. Deep maroon underparts, faintly speckled white. Female duller. Similar spp. São Tomé Bronze-naped Pigeon Columba malherbii is smaller and paler with metallic patches on neck and nape. Voice Deep, almost owl-like cooing.

Text account compilers
Clark, J.

Contributors
Carvalho, M.B., Deffontaines, J., Ekstrom, J., Gascoigne, A., Khwaja, N., Melo, M., Olmos, F., Peet, N., Shutes, S., Starkey, M., Symes, A., Taylor, J., Westrip, J.R.S. & de Lima, R.F.

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Recommended citation
BirdLife International (2024) Species factsheet: Sao Tome Olive-pigeon Columba thomensis. Downloaded from https://datazone.birdlife.org/species/factsheet/sao-tome-olive-pigeon-columba-thomensis on 23/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 23/12/2024.