NT
Giant Weaver Ploceus grandis



Taxonomy

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.

IUCN Red list criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- - -

Red List history
Year Category Criteria
2018 Near Threatened C2a(ii)
2016 Least Concern
2012 Least Concern
2009 Least Concern
2008 Least Concern
2004 Least Concern
2000 Lower Risk/Least Concern
1994 Lower Risk/Least Concern
1988 Lower Risk/Least Concern
Species attributes

Migratory status not a migrant Forest dependency Low
Land mass type Average mass -
Extent of occurrence (EOO)

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 970 medium
Number of locations -
Fragmentation -
Population and trend
Estimate Data quality Derivation Year of estimate
No. of mature individuals 2500-9999 poor suspected 2018
Population trend Decreasing suspected -
Decline (3 years/1 generation past) - - -
Decline (5 years/1 generation past) - - -
Decline (10 years/1 generation past) - - -
Decline (10 years/3 generation future) - - -
Decline (10 years/3 generation past and future) - - -
Number of subpopulations 1 - - -
Largest subpopulations 100 - - -
Generation length (yrs) 4 - - -

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.


Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
São Tomé e Príncipe N Extant Yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
São Tomé e Príncipe São Tomé lowland forests
São Tomé e Príncipe São Tomé montane and cloud-forests

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Artificial/Terrestrial Arable Land suitable resident
Artificial/Terrestrial Plantations suitable resident
Artificial/Terrestrial Subtropical/Tropical Heavily Degraded Former Forest major resident
Forest Subtropical/Tropical Moist Lowland suitable resident
Savanna Dry marginal resident
Shrubland Subtropical/Tropical Moist suitable resident
Altitude 0 - 1500 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Agriculture & aquaculture Annual & perennial non-timber crops - Small-holder farming Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation, Ecosystem conversion
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Rattus rattus Timing Scope Severity Impact
Ongoing Minority (<50%) Unknown Unknown
Stresses
Species mortality

Utilisation
Purpose Primary form used Life stage used Source Scale Level Timing
Pets Whole Adults and juveniles Wild International Non-trivial Recent
Pets/display animals, horticulture - - International Non-trivial Recent

Recommended citation
BirdLife International (2018) Species factsheet: Ploceus grandis. Downloaded from http://www.birdlife.org on 13/12/2018. Recommended citation for factsheets for more than one species: BirdLife International (2018) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 13/12/2018.