Usambara Weaver Ploceus nicolli


Taxonomic note

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.
Dowsett, R. J.; Forbes-Watson, A. D. 1993. Checklist of birds of the Afrotropical and Malagasy regions. Tauraco Press, Li
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

IUCN Red list criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- C2a(i) B1ab(ii,iii,v); C2a(i); D1

Red List history
Year Category Criteria
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 -
Extent of occurrence (EOO)

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 51,900 medium
Number of locations 11-100 -
Fragmentation -
Population and trend
Estimate Data quality Derivation Year of estimate
No. of mature individuals 600-1700 poor estimated 2000
Population trend Decreasing medium 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 2-100 - - -
Largest subpopulations - - -
Generation length (yrs) 4 - - -

Population justification: The total population has been guessed to number over 1,000 individuals (Seddon et al. 1999b), 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 estimate is equivalent to 667-1,666 mature individuals, rounded here to 600-1,700 mature individuals. However, this estimate may warrant increasing in the future in line with possible higher population estimates.

Trend justification: The species's forest habitat is being cleared, altered and fragmented for agriculture, plantations and timber extraction (Svendsen and Hansen 1995; Cordeiro 1998), thus the population is suspected to be in decline at an unknown rate.

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
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
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
Ecosystem degradation
Climate change & severe weather Habitat shifting & alteration Timing Scope Severity Impact
Future Whole (>90%) Unknown Unknown
Indirect ecosystem effects, Ecosystem degradation
Human intrusions & disturbance Recreational activities Timing Scope Severity Impact
Ongoing Majority (50-90%) Negligible declines Low Impact: 5
Species disturbance, Ecosystem degradation

Recommended citation
BirdLife International (2020) Species factsheet: Ploceus nicolli. Downloaded from http://www.birdlife.org on 13/07/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 13/07/2020.