NT
Usambara Weaver Ploceus nicolli



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
- C2a(i) C2a(i); D1

Red List history
Year Category Criteria
2021 Near Threatened C2a(i); D1
2016 Endangered C2a(i)
2012 Endangered C2a(i)
2008 Endangered C2a(i)
2004 Endangered
2000 Endangered
1996 Vulnerable
1994 Vulnerable
1988 Threatened
Species attributes

Migratory status not a migrant Forest dependency High
Land mass type Land-mass type - continent
Average mass -
Distribution

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 51,900 medium
Number of locations -
Severely Fragmented -
Population and trend
Value Data quality Derivation Year of estimate
No. of mature individuals 600-1700 poor inferred 2000
Population trend Decreasing medium inferred -
Decline (3 years/1 generation past) - - -
Decline (5 years/1 generation past) - - -
Decline (10 years/1 generation past) - - -
Decline (10 years/3 generation future) 1-15 - - -
Decline (10 years/3 generation past and future) 1-15 - - -
Number of subpopulations 2-3 - - -
Percentage in largest subpopulation 1-89 - - -
Generation length (yrs) 3.6 - - -

Population justification: The total population has been guessed to number over 1,000 individuals (Seddon et al. 1999), and possibly over 2,500 individuals, but not more than 5,000 (L. Hansen in litt. 2016). The population in the Udzungwas alone might number 1,000-2,000 individuals (L. Hansen in litt. 2007), although it has also been guessed at 'some hundred' (Dinesen et al. 2001). Therefore, the population is conservatively placed in the range of 1,000-2,499 individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for congeners or close relatives with a similar body size, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This is roughly equivalent to 667-1,666 mature individuals, rounded here to 600-1,700 mature individuals.

Trend justification: This species is inferred to be declining due to ongoing forest loss (Global Forest Watch 2021). The forest is being cleared, altered and fragmented for agriculture, plantations and timber extraction (Svendsen and Hansen 1995; Cordeiro 1998).

Between 2000-2019, this species experienced forest cover loss of 8.1% (Global Forest Watch 2021). This species has a high forest dependency and assuming that the population declines at a similar rate, this would equate to a rate of decline of c.5% over the past 3 generations. Green et al. (2013) estimated that the entire Eastern Arc mountain range lost 26% of forests between 1975-2000, which would equate to a decline rate of 11% over 3 generations. Between 2016-2019, this species's experienced a loss of forest cover of 3% (Global Forest Watch 2021). Projected forward over 3 generations, this would equate to a loss of 8%. The overall population decline is suspected to fall into the band 1-15%.


Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
Tanzania N Extant Yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Tanzania Udzungwa National Park
Tanzania Rubeho Mountains
Tanzania Udzungwa Mountains
Tanzania Uluguru Mountains
Tanzania East Usambara Mountains
Tanzania West Usambara Mountains
Tanzania Udzungwa Mountain Range

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Forest Subtropical/Tropical Moist Montane major resident
Altitude 900 - 1850 m Occasional altitudinal limits (max) 2200 m

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 Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Stresses
Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture Wood & pulp plantations - Scale Unknown/Unrecorded Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation, Ecosystem conversion
Biological resource use Logging & wood harvesting - Unintentional effects: (subsistence/small scale) [harvest] Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation
Climate change & severe weather Habitat shifting & alteration Timing Scope Severity Impact
Future Whole (>90%) Unknown Unknown
Stresses
Indirect ecosystem effects, Ecosystem degradation
Human intrusions & disturbance Recreational activities Timing Scope Severity Impact
Ongoing Majority (50-90%) Negligible declines Low Impact: 5
Stresses
Species disturbance, Ecosystem degradation

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

Recommended citation
BirdLife International (2022) Species factsheet: Ploceus nicolli. Downloaded from http://www.birdlife.org on 01/10/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 01/10/2022.