NT
Giant Weaver Ploceus grandis



Justification

Justification of Red List Category
Despite being described as common, this species potentially has a small population size, which could be declining as its tolerance of degraded habitats may bring it into contact with introduced predators. There is no strong evidence to support declines though, and so the species is listed here as Near Threatened. Further evidence regarding population trends and size could though mean that the species warrants downlisting in the future.

Population justification
The species has been described as common across the island (Fry and Keith 2004, Craig 2018). Yet, a recent survey found the species at only 268 out of 3,056 point counts (de Oliveira Soares 2017). Using population densities estimates for congeners (although these are for continental species), the population size may fall in the range 1,000-2,499 mature individuals. However, this species is gregarious, so multiple individuals can be found at a single point count, and island species often occur at higher densities (R. F. de Lima in litt. 2018). Therefore, the population size is very tentatively placed here in the range 2,500-9,999 mature individuals.

Trend justification
The species is tolerant of degraded habitats, so habitat degradation is unlikely to impact this species. However, its tolerance of degraded habitats may bring it into contact with introduced predators such as House Rats (Rattus rattus), but it is highly uncertain whether such predators are having an impact on the species at all. The species is very precautionarily suspected to be declining, but further information could show the species to be stable or even increasing.

Distribution and population

Ploceus grandis is endemic to the island of São Tomé, São Tomé and Príncipe, and is thought to be common on the island (Craig 2018).

Ecology

This species occurs in a range of habitat types up to 1,500m, from forest and plantations to degraded habitats, although seldom in savanna (Fry and Keith 2004, Craig 2018); and surveys have even resulted in this species being more commonly seen in non-forest habitats and plantations than both primary and secondary forest combined (de Oliveira Soares 2017).

Threats

This species prefers habitats with an intermediate level of disturbance (R. F. de Lima in litt. 2018). While the species could therefore not be as severely impacted by forest loss as other species endemic to the island, this could mean that population core of this species relies on anthropogenic environments, which may be prone to the impact of human activities than more natural environments (R. F. de Lima in litt. 2018). Therefore, ongoing agricultural intensification may be impacting this species more than most of the other endemics (R. F. de Lima in litt. 2018). The species's tolerance of degraded habitats may also mean it is more likely to come into contact with introduced predators such as House Rats (Rattus rattus), but it is uncertain whether such invasives are having an impact on this species.

Conservation actions

Conservation Actions Underway
No targeted conservation actions are known.

Conservation Actions Proposed
Conduct research to get better estimates of the population size and trend. Investigate to what extent certain threats may be impacting the species. Maintain suitable land-use regimes to provide habitat with an intermediate level of disturbance.

Acknowledgements

Text account compilers
Butchart, S., Westrip, J., Ekstrom, J.

Contributors
de Lima, R.


Recommended citation
BirdLife International (2018) Species factsheet: Ploceus grandis. Downloaded from http://www.birdlife.org on 16/12/2018. Recommended citation for factsheets for more than one species: BirdLife International (2018) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 16/12/2018.