Data Zone
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.
| Critically Endangered | Endangered | Vulnerable |
|---|---|---|
| - | - | - |
| Year | Category | Criteria |
|---|---|---|
| 2023 | Near Threatened | D1 |
| 2016 | Endangered | A2bcd+3bcd+4bcd;C2a(ii) |
| 2013 | Endangered | A2bcd+3bcd+4bcd;C2a(ii) |
| 2012 | Endangered | A2bcd+3bcd+4bcd;C2a(ii) |
| 2008 | Endangered | A2b,c,d; A3b,c,d; A4b,c,d; C2a(ii) |
| 2007 | Endangered | |
| 2006 | Endangered | |
| 2004 | Endangered | |
| 2000 | Endangered | |
| 1996 | Endangered | |
| 1994 | Endangered | |
| 1988 | Threatened |
| Migratory status | not a migrant | Forest dependency | medium |
| Land-mass type |
continent |
Average mass | - |
| Estimate | Data quality | |
|---|---|---|
| Extent of Occurrence (breeding/resident) | 1,200,000 km2 | medium |
| Extent of Occurrence (non-breeding) | 1,810,000 km2 | medium |
| Number of locations | 11-100 | - |
| Severely fragmented? | no | - |
| Estimate | Data quality | Derivation | Year of estimate | |
|---|---|---|---|---|
| Population size | 1360-1510 mature individuals | good | estimated | 2023 |
| Population trend | increasing | poor | estimated | - |
| Generation length | 12.55 years | - | - | - |
| Number of subpopulations | 2 | - | - | - |
| Percentage of mature individuals in largest subpopulation | 65-70% | - | - | - |
Population justification: Although historically widespread across the South and South-East Asian subcontinents, Leptoptilos dubius is now confined to two isolated subpopulations: (1) in north-east India; and (2) in Cambodia.
In Assam, India, birds were accurately counted across eight known areas in 2022-2023, yielding a total of 380 breeding pairs (or c. 760 mature individuals) and a large non-breeding population of at least 1,070 birds (P. D. Barman in litt. 2023). This is equivalent to a total of 1,830 birds in the state, which is similar to an independent count of 1,950 birds made by Early Birds (an NGO in Assam) in the same year (P. D. Barman in litt. 2023). Outside of Assam, the only known breeding population in India lies in Bihar, where 600 birds were recently counted, comprising 100-125 active nests, or c. 200-250 mature individuals, between 2019 and 2021 (Choudhary and Abdullah 2023). Summing these data, the north-east India subpopulation is now considered to number at least 960-1,010 mature individuals, or 2,430-2,550 birds.
In Cambodia, recent (2020 and 2021) counts have been of 200-250 breeding pairs (400-500 mature individuals), or c. 750 birds, at Prek Toal (R. Tizard in litt., Wetlands International 2021, Timmins et al. in press), representing a marked increase on two decades ago. Overall, the global population is therefore estimated to be 1,360-1,510 mature individuals, or 3,180-3,300 birds.
Trend justification: Recent (post 2000) data indicate that both subpopulations (in north-east India, and Cambodia) are increasing. In north-east India, the population has increased to at least c. 1,800 in 2022–2023 (P. D. Barman in litt. 2023). In Cambodia, a colony of c. 20 breeding pairs (in 2004) in Kulen Promtep Wildlife Sanctuary was extirpated by 2013 (Harrison and Mao 2017), but this loss has been made up for numerically by increases at Prek Toal, where there are now more than 200 breeding pairs (Timmins et al. in press), up from c. 150 pairs in 2013/2014 (Visal and Mahood 2015), and fewer than 50 pairs in the early 2000s (Collar et al. 2001, Wetlands International 2021). The increases observed in both countries stem entirely from conservation action in both subpopulations (e.g. Barman et al. 2020) and these look set to continue into the future, although widespread recoveries are likely to be constrained by the historic clearance of suitable habitat in its range (especially in South-East Asia), and remaining high hunting pressure in some countries (e.g. Lao PDR: Duckworth et al. 1999, Timmins et al. in press). Moreover, the Prek Toal colony is not considered wholly secure, with future possible threats including avian influenza, fire, development, and the long-term disruption of the Mekong–Tonle Sap flood regime (C. Poole in litt. 2023). Accordingly, while the population is on a trajectory to increase in the future, close monitoring is needed to ensure this is realised.
Despite the successes documented, the population size of this species remains substantially depleted, with BirdLife International (2001) estimating then that the global population of the species likely represented 0.1-1% of the total in 1900—it has scarcely recovered these losses since, with the amelioration of threats highly localised, and the species occupying only a small percentage of the range it once did. The majority of these declines—driven chiefly by persecution and habitat modification—are suspected to have occurred in the first half of the 20th century (see Birdlife International 2001 for summary), although there is limited evidence that the population in 2023 remains smaller than three generations ago (1985). For example, records from Rajasthan (India), Bangladesh and (with some uncertainty) Myanmar persisted until at least the 1990s (BirdLife International 2001), and in Thailand until the early 2000s (BirdLife International 2001, eBird 2023) since which there has been almost no repeat. [Nonetheless, with recoveries in Cambodia, sporadic future records in Thailand (and perhaps Lao PDR and Viet Nam) could be expected.] While there is therefore relatively high confidence that the species has declined since 1985, there is considerable uncertainty in determining the rate at which it has done so.
Assuming conservation action continues to be successful in India and Cambodia (with parallel support in neighbouring states, e.g. in Thailand), population increases are projected to occur in the future, however it is unknown whether the causes of past declines are fully reversible; even if they are, full recovery is likely to take many decades.
| Country/Territory | Presence | Origin | Resident | Breeding visitor | Non-breeding visitor | Passage migrant |
|---|---|---|---|---|---|---|
| Bangladesh | possibly extinct | native | yes | |||
| Cambodia | extant | native | yes | |||
| India | extant | native | yes | |||
| Laos | possibly extinct | native | yes | |||
| Myanmar | possibly extinct | native | yes | |||
| Nepal | possibly extinct | native | yes | |||
| Pakistan | possibly extinct | native | yes | |||
| Thailand | possibly extinct | native | yes | |||
| Vietnam | possibly extinct | native | yes |
| Habitat (level 1) | Habitat (level 2) | Importance | Occurrence |
|---|---|---|---|
| Artificial/Terrestrial | Arable Land | major | non-breeding |
| Artificial/Terrestrial | Urban Areas | major | resident |
| Forest | Subtropical/Tropical Dry | suitable | 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 | non-breeding |
| Wetlands (inland) | Permanent Rivers/Streams/Creeks (includes waterfalls) | major | non-breeding |
| Altitude | 0 - 500 m | Occasional altitudinal limits | (max) 1500 m |
| Threat (level 1) | Threat (level 2) | Impact and Stresses | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Agriculture & aquaculture | Annual & perennial non-timber crops - Agro-industry farming | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | No decline | Low Impact: 4 | ||||||
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| Agriculture & aquaculture | Annual & perennial non-timber crops - Small-holder farming | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | No decline | Low Impact: 4 | ||||||
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| Agriculture & aquaculture | Livestock farming & ranching - Small-holder grazing, ranching or farming | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | No decline | Low Impact: 4 | ||||||
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| Agriculture & aquaculture | Marine & freshwater aquaculture - Subsistence/artisinal aquaculture | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | No decline | Low Impact: 4 | ||||||
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| Biological resource use | Hunting & trapping terrestrial animals - Intentional use (species is the target) | Timing | Scope | Severity | Impact | ||||
| Past, Unlikely to Return | Majority (50-90%) | Rapid Declines | Past Impact | ||||||
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| Biological resource use | Hunting & trapping terrestrial animals - Persecution/control | Timing | Scope | Severity | Impact | ||||
| Past, Unlikely to Return | Majority (50-90%) | Rapid Declines | Past Impact | ||||||
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| Biological resource use | Logging & wood harvesting - Unintentional effects: (subsistence/small scale) [harvest] | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | No decline | Low Impact: 4 | ||||||
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| Human intrusions & disturbance | Recreational activities | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | No decline | Low Impact: 4 | ||||||
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| Invasive and other problematic species, genes & diseases | Viral/prion-induced diseases - Avian Influenza Virus (H5N1 subtype) | Timing | Scope | Severity | Impact | ||||
| Unknown | Whole (>90%) | Unknown | Unknown | ||||||
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| Natural system modifications | Dams & water management/use - Abstraction of ground water (agricultural use) | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | Unknown | Unknown | ||||||
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| Natural system modifications | Dams & water management/use - Large dams | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | Unknown | Unknown | ||||||
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| Natural system modifications | Fire & fire suppression - Trend Unknown/Unrecorded | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | Unknown | Unknown | ||||||
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| Pollution | Agricultural & forestry effluents - Herbicides and pesticides | Timing | Scope | Severity | Impact | ||||
| Past, Likely to Return | Minority (<50%) | Negligible declines | Past Impact | ||||||
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| Pollution | Domestic & urban waste water - Type Unknown/Unrecorded | Timing | Scope | Severity | Impact | ||||
| Past, Likely to Return | Majority (50-90%) | Slow, Significant Declines | Past Impact | ||||||
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| Pollution | Garbage & solid waste | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | No decline | Low Impact: 4 | ||||||
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| Residential & commercial development | Commercial & industrial areas | Timing | Scope | Severity | Impact | ||||
| Past, Likely to Return | Majority (50-90%) | Slow, Significant Declines | Past Impact | ||||||
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| Residential & commercial development | Housing & urban areas | Timing | Scope | Severity | Impact | ||||
| Past, Likely to Return | Majority (50-90%) | Slow, Significant Declines | Past Impact | ||||||
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| Purpose | Scale |
|---|---|
| Food - human | subsistence, national |
| Pets/display animals, horticulture | subsistence, national |
Recommended citation
BirdLife International (2024) Species factsheet: Greater Adjutant Leptoptilos dubius. Downloaded from
https://datazone.birdlife.org/species/factsheet/greater-adjutant-leptoptilos-dubius 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.