Data Zone
Justification of Red List category
Although this species may have a small range, it is not believed to approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). Therefore, the species has been listed here as Least Concern.
Population justification
This species appears to occur as frequently in secondary forest and plantations as in native forest (see de Oliveira Soares 2017). Based on density estimates of Dallimer et al. (2009), the population size is likely to be considerably greater than 20,000 mature individuals, potentially even up to 300,000 individuals (R. F. de Lima in litt. 2018).
Trend justification
The species's population is suspected to be experiencing a continuing decline owing to habitat loss and degradation coupled with predation by introduced species and persecution by humans (del Hoyo et al. 2005, R. Faustino de Lima in litt. 2010).
Turdus olivaceofuscus is endemic to São Tomé, São Tomé e Príncipe. It is widely distributed at low densities (Atkinson et al. 1991, Christy and Clarke 1998), being found in most habitats with tree cover (Dallimer et al. 2010).
The species inhabits primary and secondary forest up to 2,024 m (Atkinson et al. 1991, Christy and Clarke 1998). It prefers lowland habitats, and also occupies cocoa plantations with Erythrina shade trees, orchards, gardens and coffee plantations, as well as dry woodland in savanna and cloudforest (del Hoyo et al. 2005, Dallimer et al. 2010). However, it is far less abundant in plantations compared to forest (de Lima et al. 2014). It feeds on invertebrates and fruit. Breeding takes place from the end of July until January, with a peak between October and December. The nest, in which two eggs are laid, is a bulky cup of mixed dry plant matter and mud, usually situated 0.5-4 m above the ground in dense vegetation (del Hoyo et al. 2005).
The area of remaining primary forest is small and could be vulnerable to destruction and degradation in the future. On-going changes in land use are driven largely by a growing human population and foreign investment in agricultural projects, such as the expansion of oil palm cultivation (R. F. de Lima in litt. 2010). Land privatisation is leading to an increase in the number of small farms and the clearance of trees. The removal of shade trees in cocoa plantations is a local threat (del Hoyo et al. 2005). Road developments along the east and west coasts of São Tomé are increasing access to previously remote areas (A. Gascoigne in litt. 2000). As such, habitat loss and degradation are becoming increasingly serious threats (R. F. de Lima in litt. 2010). Many nests are destroyed by Brown Rats Rattus norvegicus (del Hoyo et al. 2005). It also suffers an unquantified level of mortality through persecution by children who commonly target the species with slingshots (R. F. de Lima in litt. 2010).
Conservation Actions Underway
No targeted conservation action is known for this species.
24 cm. Dull olive-brown above from head below eye to tail; head slightly darker. Chin and throat dusky buff with whitish streaks. Dusky buff scales on buff-washed breast, shading to dusky-buff scalloping on whitish remaining underparts. Underwing coverts pale orange-buff against creamy secondaries. Iris brown to red. Bill large and dark with lighter yellowish tip. Legs dark brownish-grey. Sexes similar. Juvenile like adult with light buff flecking above and blotched brown below. Similar spp. T. xanthorhynchus on Príncipe is darker with coarser scaling on the underparts and yellow bill and legs.
Text account compilers
Khwaja, N., O'Brien, A., Robertson, P., Starkey, M., Taylor, J., Peet, N., Westrip, J.
Contributors
Atkinson, P., d'Assis Lima, S., Gascoigne, A., de Lima, R.
Recommended citation
BirdLife International (2024) Species factsheet: Sao Tome Thrush Turdus olivaceofuscus. Downloaded from
https://datazone.birdlife.org/species/factsheet/sao-tome-thrush-turdus-olivaceofuscus on 26/12/2024.
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 26/12/2024.