Data Zone
Justification of Red List category
This species was, at one time, considered Endangered because of rapid population declines, but since the early-to-mid-2000s, dedicated conservation action in its two remaining subpopulations (north-east India and Cambodia) has reversed this trend. The population trend is now increasing, and likely has been for more than ten years, meaning its immediate extinction risk is low. Nonetheless, the current global population is still only 1,360-1,510 mature individuals, and Greater Adjutant is probably still entirely conservation dependent, such that any weakening of protection or reduction in conservation effort could lead to future declines once more; were this to occur, the species' moderately small population size renders it especially vulnerable. Accordingly it is currently listed as Near Threatened, but it is crucial that robust monitoring and effective conservation action continue to ensure that this species' recovery continues.
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.
This species has undergone a catastrophic range contraction since the 19th century, with extant breeding populations in only India and Cambodia. Historically, it had a distribution that spanned much of continental South and South-East Asia, from Pakistan (where it was a non-breeding, but regular, visitor), through much of India, Nepal, Bangladesh, Myanmar, Thailand, Lao PDR and Viet Nam, in all of which it, presumably, at one time bred, albeit with varying degrees of evidence to back up this assertion (BirdLife International 2001). From all of these latter named states, the species is now assumed extirpated, with any recent records almost certainly wanderers from elsewhere (giving rise to optimism about future colonisation if threats can be adequately mitigated). In India, all birds are now confined to Assam and Bisar (see Population Size justification). In Cambodia, it is now confined to only Prek Toal, having been extirpated from Kulen Promtep Wildlife Sanctuary in 2013 due to forest clearance.
While breeding in the dry season (October-April/May) it inhabits wetlands, nesting in tall trees with closed canopies and bamboo clumps around nesting trees, and historically on cliffs. Breeding is thought to coincide with the dry season in order to take advantage of abundant prey as water levels recede (Singha et al. 2003). In north-east India, it occurs close to and within urban areas (A. Choudhury in litt. 2016), feeding around wetlands in the breeding season, and dispersing to scavenge at rubbish dumps, abattoirs and burial grounds at other times. In Cambodia, it breeds in freshwater flooded forest and areas of dry forest with ephemeral pools, otherwise dispersing to seasonally inundated forest, carcass dumps, tall wet grassland, mangroves and intertidal flats. It generally inhabits the lowlands but is occasionally found up to 1,500 m (Elliott and Kirwan 2020).
The chief cause of this species' catastrophic decline over the past 200 years has been the destruction and disturbance of its breeding and feeding sites. Hunting of adults and the collection of eggs and chicks have caused (rapid) declines in parts of the range also, and this threat would have likely been the proximate cause of extirpation in South-East Asia were the Prek Toal colony not protected through community engagement in the early 2000s. BirdLife International (2001) summarised the historic threats to this species as follows: (1) Habitat loss and modification caused by the drainage, degradation and pollution of wetlands used for foraging, as well as the clearance of breeding colonies for urban development and agricultural expansion; (2) Disturbance, particularly of breeding colonies, although this species is said to be somewhat tolerant of human disturbance; (3) Persecution, seen as a threat throughout much of its range, with birds historically hunted in India and sometimes killed because of locally held superstitious beliefs. In some former range states, especially Lao PDR this is probably the main cause of extirpation and greatly limits its recovery potential (Duckworth et al. 1999, Timmins et al. in press); (4) Lack of awareness of protective status and the rarity of the species; (5) Disease; and (6) Miscellaneous, including for example, the sporadic collision of this species with power lines. Whether the non-steroidal anti-inflammatory drug (NSAID) diclofenac, used to treat domestic livestock, impacted this scavenging species in India, as it did vultures, is unknown.
The recovery of this species in India and Cambodia has occurred solely through the amelioration of the most critical of these threats, and the species should continue to be regarded as wholly conservation dependent. Moreover, if the population is to continue to increase in abundance and range, then the amelioration and/or mitigation of these threats will be critical. Contemporarily, many threats remain for this species in current range states and beyond; while none of these are driving global declines (given the species' increasing population trend) they are in places likely preventing local and regional recovery. In India, the destruction of nesting trees does still occur in places (A. Choudhury in litt. 2023), mostly for urban and agricultural expansion, as does accidental poisoning on open rubbish dumps and the accidental ingestion of polythene bags (J. Mandal in litt. 2016). Persecution in India may still occur locally, but has been greatly reduced due to successful community engagement programmes. In South-East Asia, the entire population is now breeding at Prek Toal. Although this site has been subject to concerted and successful conservation action (virtually eliminating the threat of hunting), a number of threats do remain including avian influenza (a threat that should be considered serious throughout its range given the small number of colonies), fires (as occurred in 2016) and the long-term disruption of the Mekong-Tonle Sap flood regime (see, e.g., Arias et al. 2012, Morovati et al. 2023, and references therein). As recently as 2013, clearance of forest at Kulen Promtep Wildlife Sanctuary in the Northern Plains of Cambodia caused this population to go extinct. Elsewhere in South-East Asia, hunting is probably preventing the recolonisation of Lao PDR (Duckworth et al. 1999, Timmins et al. in press), while in Thailand (where modern persecution of large waterbirds is greatly reduced) recovery is possible and should be considered a conservation priority.
Conservation Actions Underway
Both subpopulations for this species are conservation dependent and the persistence of this species is therefore reliant on well-funded community-based conservation; if this ceases, the species is very likely to decline and its extinction risk will increase once more. In India, the community work of P. D. Barman is directly responsible for the change of fortunes in this species: The project was initiated in 2007 and combined community development, education and outreach; in particular, the work bestowed a pride and ownership for the storks by the villagers, including a (now large) group of rural woman named the 'Hargila Army' who the project sought to empower to protect adjutant nests and help their economic livelihoods (see Barman et al. 2020 for more detailed summary). In particular, the project supported the sewing of traditional textiles, especially the gamosa (a traditional Assamese scarf) which are decorated with stork motifs and both sold and gifted to raise awareness. Critically, the project has deliberately avoided the use of direct economic payments to protect nests, but rather has relied (successfully) on providing economic opportunities for local people. The conservation program has also invested heavily in the education of children and students, reaching and educating 12,000 school children in its first 12 years (Barman et al. 2020). This project has seen the population of nesting Greater Adjutants in Assam increase rapidly (Barman et al. 2020, P. Barman in litt. 2023); the next planned phase of the program is the 'Hargila Dream: 5,000 storks by 2030'. This phase aims to increase the number of Greater Adjutants in north-east India to 5,000 birds by 2030, but the success of this project will rely on appropriate resourcing and funding by donors, and support from policy makers. The continued recovery of this species in north-east India will likely rely on the success of this project.
Similar successes have been achieved in Cambodia, where the protection on the Prek Toal colony (in the Tonle Sap Great Lake RAMSAR site) has caused the number of breeding birds to increase from fewer than 50 pairs in the early 2000s (BirdLife International 2001) to more than 200 breeding pairs in 2021 (Timmins et al. in press). This recovery has been driven by the protection of breeding birds at Prek Toal, with the species no longer breeding anywhere else in South-East Asia. This scheme has achieved success by employing round-the-clock monitoring provided by a team of rangers—including former poachers and egg robbers—to increase breeding productivity; this work has been supported logistically and technically by WCS.
Conservation Actions Proposed
The most important conservation action for this species is ensuring that the currently operating conservation programmes in India and Cambodia are continued. Although this species is currently not considered at imminent risk of extinction, this status is dependent on conservation and will likely quickly deteriorate if these projects do not continue to be appropriately resourced. This species' population size is likely <1% of what it was two centuries ago; its occupied range is probably an even lower percentage. Accordingly, there is the great potential for future recovery. In India, the 'Hargila Dream: 5,000 storks by 2030' project provides an achievable target with a proven track record of increasing adjutant populations; this should be prioritised and expanded in neighbouring areas. In South-East Asia, the greatest risk to this species is provided by the fact that the entire breeding population is now at Prek Toal, a site that continues to be subject to numerous threats (e.g. Morovati et al. 2023). In addition to mitigating these (particularly preventing further damage to the broader Tonle Sap landscape), establishing a breeding population elsewhere should be considered a priority. A species action/recovery plan should be developed to best evaluate the ideas discussed here to enable this species to inhabit a greater percentage of its former range. In neighbouring Lao PDR, where this species was once presumably widespread through the country's lowlands (Duckworth et al. 1999), there is suitable habitat for breeding and foraging birds, with hunting probably the only obstacle to recolonisation (Timmins et al. in press). Surveys to determine whether birds are already occasionally visiting southernmost Lao PDR are needed, as is effective community engagement and education so that the establishing of breeding colonies is possible. Sites near the Cambodian/Lao PDR border (for example, Dong Khanthung) should be prioritised. In Thailand, wetland bird populations have (partially) recovered in the past twenty years (P. Round pers. comm.) and this country should also be considered a priority for population and range expansion over the next decade. Here, hunting is a less pervasive problem than Lao PDR and may therefore prove itself a more realistic and immediate possibility. Identifying sites and means of attracting birds to breed should be undertaken; sites close to the Cambodian border should be prioritised to facilitate natural recolonisation. The conservation status of this species remains precarious and its current Near Threatened status relies on the continued generating of good data: robust monitoring must therefore also continue.
145-150 cm. Huge, dark stork with very thick bill and pendulous neck-pouch. Pinkish naked head, white neck-ruff. Pale grey greater coverts and tertials contrasting with otherwise dark upperwing. Underwing-coverts paler than flight feathers. Juvenile has narrower bill than adult, denser head and neck-down and, initially, all dark wings. Similar spp. Lesser Adjutant L. javanicus is smaller, lacks neck pouch, has black greater coverts and tertials.
Text account compilers
Berryman, A.
Contributors
Barman, P., Choudhury, A., Mahood, S., Mandal, J., Poole, C., Rahmani, A. & Tizard, R.J.
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.