VU
Pemba Green-pigeon Treron pembaensis



Taxonomy

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.

IUCN Red list criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- - C2a(ii)

Red List history
Year Category Criteria
2016 Vulnerable C2a(ii)
2012 Vulnerable C2a(ii)
2008 Vulnerable C2a(ii)
2006 Vulnerable
2004 Least Concern
2000 Lower Risk/Least Concern
1994 Lower Risk/Near Threatened
1988 Lower Risk/Least Concern
Species attributes

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

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 1,300 medium
Number of locations -
Fragmentation -
Population and trend
Estimate Data quality Derivation Year of estimate
No. of mature individuals 2500-9999 medium estimated 2006
Population trend Decreasing poor 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) 1-19 - - -
Decline (10 years/3 generation past and future) - - -
Number of subpopulations 1 - - -
Largest subpopulations 100 - - -
Generation length (yrs) 4.2 - - -

Population justification: Recent visitors to Pemba have struggled to find this species, which now appears to be rather rare (A. Sander in litt. 2004, M. Virani in litt. 2005, J. Wolstencroft in litt. 2005, 2007, N. Burgess in litt. 2012). Population estimate = 5-8 individuals/km2 × 400 km2 (45% of EOO) = 2,000-3,200 individuals (density range from up to lower quartile of six congeners in BirdLife Bird Population Density Spreadsheet). Perhaps best placed in the band 2,500-9,999 mature individuals at present: this estimate requires validation, and direct information on area of suitable habitat, population densities in various habitats, and total population size may lead to adjustment of this estimate up or down. The estimate equates to 3,750-14,999 individuals, rounded here to 3,500-15,000 individuals.

Trend justification: Loss and degradation of both primary and secondary habitat is occurring (A. Hija in litt. 2005, Virani 2005, M. Virani in litt. 2005, J. Wolstencroft in litt. 2007), with Zanzibar's (Pemba and Unguja) forest declining at 1.2% per year (Siex et al. 2013). This is likely to decrease densities of this species at a slow rate (Catry et al. 2000).


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 Pemba Island

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Artificial/Terrestrial Plantations suitable resident
Artificial/Terrestrial Rural Gardens suitable resident
Forest Subtropical/Tropical Moist Lowland major resident
Altitude 0 - 79 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Agriculture & aquaculture Annual & perennial non-timber crops Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Stresses
Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture Wood & pulp plantations Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem conversion
Biological resource use Logging & wood harvesting 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
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases Timing Scope Severity Impact
Ongoing Minority (<50%) Negligible declines Low Impact: 4
Stresses
Reduced reproductive success
Residential & commercial development Tourism & recreation areas Timing Scope Severity Impact
Future Minority (<50%) Slow, Significant Declines Low Impact: 3
Stresses
Ecosystem degradation, Ecosystem conversion

Recommended citation
BirdLife International (2019) Species factsheet: Treron pembaensis. Downloaded from http://www.birdlife.org on 19/09/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/09/2019.