EN
Sao Tome Green-pigeon Treron sanctithomae



Justification

Justification of Red List Category
This species is classified as Endangered because it is confined to a single island on which high hunting pressure (both for subsistence and for trade) and habitat degradation are suspected to be a driving rapid decline in its single population within its very small range.

Population justification
Carvalho (2015) estimates the population to be in the range 37,007-109,255 individuals, which roughly equates to 24,670-72,840 mature individuals.

Trend justification

The population is inferred to be declining owing to hunting pressure. This species is a preferential target for hunters, and has disappeared or become scarce in accessible areas (Carvalho 2015).

Distribution and population

Treron sanctithomae is endemic to the island of São Tomé, São Tomé e Príncipe (and formerly also nearby Ilhéu das Rolas (Jones and Tye 2006). It was formerly abundant and remains common at some fruiting trees in forests and less well-visited plantation areas, but is now nearly absent from the most populated and drier northeast of the island (Soares et al. 2020), with unsustainable levels of hunting (Carvalho 2015). The species often concentrates around fruiting trees, making it an easy target for hunters. The global population has been estimated at 37,007 - 09,255 total individuals, (best estimate 61,511) and hunting is suspected to be causing population declines across the range, pushing the species into more inaccessible areas (Carvalho 2015, based on Soares et al. 2020). It is estimated to be restricted to 391 km2 (based on Soares et al. 2020).

Ecology

It occurs in mature primary and secondary forest, tolerating forest degradation and also occurring in plantations at lower densities (Carvalho et al. 2015; Soares et al. 2020). It is found from sea-level to 1,800 m, but is more common above 300 m (del Hoyo et al. 1997; Gibbs et al. 2001; Carvalho et al. 2015; Soares et al. 2020). It is generally sedentary but makes local elevational movements related to food availability and breeding. Breeding has been recorded from November-May, with the nest built on a horizontal branch or in a tree fork (del Hoyo et al. 1997; Gibbs et al. 2001; Jones and Tye 2006). It is a frugivore, feeding mainly in the canopy on a variety of fruits, particularly figs (Jones and Tye 2006; Carvalho et al. 2015; Coelho 2016). 

Threats

Hunting represents the primary threat to the species, as it is caught in large numbers for consumption in rural communities and by commercial hunters to sell to bars in the capital (Carvalho 2015). Some commercial hunters can kill large numbers at a time, for example, around 30 were killed and a further 30 wounded in a single morning's hunting trip (R. Rocha in litt. 2011; Carvalho 2015). Hunting pressure is much greater in accessible habitats, and the species is easy to catch with slingshots or air guns (Carvalho 2015). Current distribution is thought to be determined by hunting pressure (Carvalho et al. 2015), including extirpation. Habitat loss is also an important threat to the species. Historically, this was from clearance for coffee and cocoa plantations. Now abandoned, these have transitioned into large extents of secondary forest. Today, timber extraction, and agricultural expansion and intensification are threatening the forest, particularly in the north of the island (Atkinson et al. 1991; Oyono et al. 2014 ). The imminent offshore oil exploitation, and ongoing population and economic booms are creating the risk of infrastructure development which may threaten the species's habitat (Oyono et al. 2014). 

Conservation actions

Conservation Actions Underway
An important part of this species's range is within the legally protected São Tomé Oho Natural Park. This species is protected from hunting within protected areas and between October and February. There are several ongoing projects supporting Biodiversity Conservation, Protected Area management, and sustainable management of forests in São Tomé and Principe, for example the ECOFAC6 intiative, 2018-2022. 

Conservation Actions Proposed
Research ecological requirements, particularly with breeding and feeding. Monitor hunting pressure, population size and population trends. Ensure the implementation of existing environmental laws. Implement policies and raise awareness to reduce hunting pressure and to reduce off-take to sustainable levels. 

Acknowledgements

Text account compilers
Clark, J.

Contributors
Butchart, S., Carvalho, M.B., Deffontaines, J., Ekstrom, J., Khwaja, N., Olmos, F., Rocha, R., Symes, A., Westrip, J.R.S. & de Lima, R.F.


Recommended citation
BirdLife International (2022) Species factsheet: Treron sanctithomae. Downloaded from http://www.birdlife.org on 16/08/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 16/08/2022.