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

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
A2cd+3cd+4cd; C2a(i)	A2cd+3cd+4cd; C2a(i); D	A2cd+3cd+4cd; C2a(i); D1

Red List history

Year	Category	Criteria
2018	Critically Endangered	A2cd+3cd+4cd; C2a(i)
2016	Critically Endangered	A2cd+3cd+4cd; C2a(i)
2015	Critically Endangered	A2cd+3cd+4cd; C2a(i)
2013	Critically Endangered	A2cd+3cd+4cd;C2a(i)
2012	Critically Endangered	A2cd+3cd+4cd;C2a(i)
2010	Critically Endangered	A2c,d; A3c,d; A4c,d; C2a(i)
2009	Critically Endangered	A2c,d; A3c,d; A4c,d; C2a(i)
2008	Critically Endangered
2004	Critically Endangered
2000	Critically Endangered
1996	Critically Endangered
1994	Critically Endangered
1988	Threatened

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

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	120,000 km2	medium
Severely fragmented?	yes	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	194 mature individuals	medium	estimated	2014
Population trend	decreasing	poor	inferred	1993-2017
Rate of change over the past 10 years/3 generations (longer of the two periods)	80-99%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	80-100%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	80-100%	-	-	-
Generation length	8 years	-	-	-
Number of subpopulations	3-10	-	-	-
Percentage of mature individuals in largest subpopulation	1-89%	-	-	-

Population justification: An assessment of the global population was made in 2014 based on newly collected data and expert opinion (including estimates of 48 and 35 mature individuals at the highest density sites) (Loveridge and Ty 2015). The population was estimated at a minimum of 194 mature individuals which is equivalent to approximately 290 individuals.

Trend justification: An extremely rapid population decline is thought to have occurred over the last three generations and an ongoing rapid decline is suspected, with future rapid declines projected to occur over the next three generations. Encroachment and land conversion continues at a rapid pace in large parts of the species's range, with additional roads leading to increasing disturbance and increased risk from hunting and loss of access to key resources (Loveridge and Ty 2015). Giant Ibises are known to be highly sensitive to human disturbance, hence increasing deforestation and habitat fragmentation have a disproportionate effect on the remaining ibis populations (Ty 2013). 

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Cambodia	extant	native	yes
Laos	extant	native	yes
Thailand	extinct	native	yes
Vietnam	extant	native	yes

Country/Territory	IBA Name
Cambodia	Chhep
Cambodia	Lomphat
Cambodia	Mondulkiri - Kratie Lowlands
Cambodia	Sekong River
Cambodia	Upper Srepok Catchment
Cambodia	Upper Stung Sen Catchment
Cambodia	Western Siem Pang
Laos	Xe Kong Plains
Vietnam	Yok Don

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Artificial/Terrestrial	Arable Land	suitable	non-breeding
Forest	Subtropical/Tropical Moist Lowland	major	resident
Grassland	Subtropical/Tropical Seasonally Wet/Flooded	major	resident
Wetlands (inland)	Permanent Freshwater Lakes (over 8ha)	major	resident
Wetlands (inland)	Permanent Freshwater Marshes/Pools (under 8ha)	major	resident
Altitude		Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Annual & perennial non-timber crops - Agro-industry farming	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Rapid Declines		Medium Impact: 7
		Stresses Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture	Annual & perennial non-timber crops - Small-holder farming	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Rapid Declines		Medium Impact: 7
		Stresses Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture	Livestock farming & ranching - Small-holder grazing, ranching or farming	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Biological resource use	Gathering terrestrial plants - Unintentional effects (species is not the target)	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation
Biological resource use	Hunting & trapping terrestrial animals - Intentional use (species is the target)	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Rapid Declines		Medium Impact: 7
		Stresses Species mortality
Biological resource use	Logging & wood harvesting - Unintentional effects: (large scale) [harvest]	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Ecosystem conversion
Human intrusions & disturbance	Work & other activities	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Rapid Declines		Medium Impact: 7
		Stresses Species disturbance
Invasive and other problematic species, genes & diseases	Problematic native species/diseases - Unspecified species	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Unknown		Unknown
		Stresses Reduced reproductive success
Natural system modifications	Dams & water management/use - Dams (size unknown)	Timing		Scope		Severity		Impact
		Future		Minority (<50%)		Rapid Declines		Low Impact: 4
		Stresses Ecosystem degradation, Ecosystem conversion
Natural system modifications	Fire & fire suppression - Increase in fire frequency/intensity	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Ecosystem degradation
Residential & commercial development	Housing & urban areas	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Rapid Declines		Medium Impact: 6
		Stresses Ecosystem degradation, Ecosystem conversion
Transportation & service corridors	Roads & railroads	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Species disturbance, Ecosystem conversion

Purpose	Scale
Food - human	subsistence, national

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Recommended citation
BirdLife International (2024) Species factsheet: Giant Ibis Thaumatibis gigantea. Downloaded from https://datazone.birdlife.org/species/factsheet/giant-ibis-thaumatibis-gigantea on 22/11/2024.
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 22/11/2024.