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). 

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).

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.