LC
Tanimbar Boobook Ninox forbesi



Taxonomy

Taxonomic note

Ninox squamipila, N. hypogramma, N. hantu and N. forbesi (del Hoyo and Collar 2014) were previously lumped as N. squamipila following Norman et al. (1998), and before then were also lumped with N. natalis as N. squamipila following Sibley and Monroe (1990, 1993).

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. Volume 1: Non-passerines. Lynx Edicions 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
2023 Least Concern
2016 Least Concern
2014 Least Concern
2012 Not Recognised
2008 Not Recognised
2004 Not Recognised
2000 Not Recognised
1994 Not Recognised
1988 Not Recognised
Species attributes

Migratory status not a migrant Forest dependency medium
Land-mass type Average mass -
Range

Estimate Data quality
Extent of Occurrence (breeding/resident) 9,500 km2
Area of Occupancy (breeding/resident) 5,200 km2
Severely fragmented? no -
Population
Estimate Data quality Derivation Year of estimate
Population size 12000-48000 mature individuals poor inferred 2022
Population trend stable - suspected -
Generation length 5.2 years - - -
Number of subpopulations 1 - - -
Percentage of mature individuals in largest subpopulation 100% - - -

Population justification: The population size of this species has not previously been quantified, although it is described as fairly common (Coates and Bishop 1997; Eaton et al. 2016, 2021). Within this species' range, c.3,000 km2 of forest remains (Global Forest Watch 2022, based on data from Hansen et al. [2013] and methods disclosed therein). Densities of congeners range widely. Based on territory size data, Jakosalem et al. (2013) thought N. rumseyi could occur at densities of up to 20 mature individuals/km2, but for the similarly sized N. boobook, Olsen et al. (2011) found territory sizes up to 10 times bigger. It is likely that N. forbesi occurs at densities closer to the former, with reports of four pairs recorded from a single point, including two within 100 m of one another in 2022 (J. Eaton in litt. 2023). Assuming an approximate density of 8-20 mature individuals/km2, and that 50-80% of suitable habitat is occupied, the population is inferred to number 12,000-48,000 mature individuals.

Trend justification: Data on population trends for this species are lacking. Although forest cover loss is ongoing (Global Forest Watch 2022, based on data from Hansen et al. [2013] and methods disclosed therein) at a rate of c.5% over the past three generations (15.6 years: 2006-2022), most losses have been along roads, and this species is noted as being very tolerant of degraded forest, even that with cleared undergrowth (J. Eaton in litt. 2023). In the absence of other threats, the population is suspected to be stable.


Country/territory distribution
Country/Territory Presence Origin Resident Breeding visitor Non-breeding visitor Passage migrant
Indonesia extant native yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Artificial/Terrestrial Subtropical/Tropical Heavily Degraded Former Forest suitable resident
Forest Subtropical/Tropical Moist Lowland major resident
Altitude 0 - 320 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Biological resource use Logging & wood harvesting - Unintentional effects: (large scale) [harvest] Timing Scope Severity Impact
Ongoing Minority (<50%) No decline Low Impact: 4
Stresses
Ecosystem degradation, Ecosystem conversion
Biological resource use Logging & wood harvesting - Unintentional effects: (subsistence/small scale) [harvest] Timing Scope Severity Impact
Ongoing Minority (<50%) No decline Low Impact: 4
Stresses
Ecosystem degradation, Ecosystem conversion

Recommended citation
BirdLife International (2024) Species factsheet: Tanimbar Boobook Ninox forbesi. Downloaded from https://datazone.birdlife.org/species/factsheet/tanimbar-boobook-ninox-forbesi on 26/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 26/12/2024.