• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Taxonomic note

Treron formosae and T. permagnus (del Hoyo and Collar 2014) were previously lumped as T. formosae 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.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2023	Near Threatened	C2a(i); D1
2016	Near Threatened	C1
2014	Near Threatened	C1
2012	Not Recognised
2008	Not Recognised
2004	Not Recognised
2000	Not Recognised
1994	Not Recognised
1988	Not Recognised

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

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	22,000 km2	medium
Extent of Occurrence (non-breeding)	101,000 km2	medium
Area of Occupancy (breeding/resident)	1,300 km2
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	1250-2000 mature individuals	poor	estimated	2022
Population trend	decreasing	poor	suspected	-
Generation length	4.6 years	-	-	-
Number of subpopulations	2	-	-	-
Percentage of mature individuals in largest subpopulation	1-89%	-	-	-

Population justification: The global population of this species has not reliably been estimated. In Taiwan (China) it is believed to breed on only two small islands: Green Island and Orchid Island, with birds disappearing from the mainland during the breeding season (but a few birds apparently remaining on Taiwan year-round: eBird 2023). While the area of these two islands is small (15 and 47 km² respectively) the species is described as not uncommon (Rueng-Shing Lin and Cheng-Ching Chiu in litt. 2023); nonetheless, Lin et al. (2016) reconciled that the total population size was still likely to be fewer than 1,000 mature individuals. On the Batanes islands (Philippines), the population size has not been estimated but applying equivalent densities as those observed on Taiwan, the population may number between 250-1,000 mature individuals. Overall therefore, the population is estimated as 1,250-2,000 mature individuals. This estimate is also congruent with the values of Brazil (2009), who suspected the population numbered between 200-2,000 mature individuals.

Trend justification: Formerly considered to be declining quite rapidly owing to habitat loss and hunting. However, forest loss in this species' range is now minimal: <1% in the three generations (13.8 years; Bird et al. 2020) to 2021 (Global Forest Watch 2022, based on data from Hansen et al. [2013] and methods disclosed therein). Hunting is a minimal threat in Taiwan but a greater one on the Babuyan and Batanes islands (Allen et al. 2006) and may be driving slow population declines. Consequently, the global population of this species is precautionarily suspected to be declining. The rate has not been quantified but is likely to be slow.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Philippines	extant	native	yes
Taiwan, China	extant	native	yes

Country/Territory	IBA Name
Philippines	Batanes Islands
Taiwan, China	Lanyu

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Artificial/Terrestrial	Rural Gardens	suitable	breeding
Artificial/Terrestrial	Rural Gardens	suitable	non-breeding
Forest	Subtropical/Tropical Moist Lowland	major	breeding
Forest	Subtropical/Tropical Moist Lowland	major	non-breeding
Forest	Subtropical/Tropical Moist Montane	major	non-breeding
Altitude	0 - 2000 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Biological resource use	Hunting & trapping terrestrial animals - Intentional use (species is the target)	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Species mortality
Biological resource use	Logging & wood harvesting - Unintentional effects: (large scale) [harvest]	Timing		Scope		Severity		Impact
		Past, Unlikely to Return		Minority (<50%)		Slow, Significant Declines		Past Impact
		Stresses Ecosystem degradation, Ecosystem conversion
Biological resource use	Logging & wood harvesting - Unintentional effects: (subsistence/small scale) [harvest]	Timing		Scope		Severity		Impact
		Past, Unlikely to Return		Majority (50-90%)		Slow, Significant Declines		Past Impact
		Stresses Ecosystem degradation

Purpose	Scale
Food - human	subsistence, national

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Recommended citation
BirdLife International (2024) Species factsheet: Taiwan Green-pigeon Treron formosae. Downloaded from https://datazone.birdlife.org/species/factsheet/taiwan-green-pigeon-treron-formosae on 22/12/2024.
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 22/12/2024.