Leptoptilos dubius 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Ciconiiformes Ciconiidae

Scientific Name: Leptoptilos dubius
Species Authority: (Gmelin, 1789)
Common Name(s):
English Greater Adjutant
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. Lynx Edicions BirdLife International.
Identification information: 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.

Assessment Information [top]

Red List Category & Criteria: Endangered A2bcd+3bcd+4bcd;C2a(ii) ver 3.1
Year Published: 2013
Date Assessed: 2013-11-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S.
Contributor(s): Choudhury, A., Chunkino, G., Clements, T., Htin Hla, T., Li, Z. & Rahmani, A.
Facilitator/Compiler(s): Benstead, P., Bird, J., Butchart, S., Davidson, P., Peet, N., Pilgrim, J., Taylor, J., Tobias, J.
This wide-ranging and long-lived species has a very small population which is declining very rapidly. For these reasons it is classified as Endangered. Recent breeding failures in Assam (the species's stronghold) provide cause for concern and need to be closely monitored.

Previously published Red List assessments:
2012 Endangered (EN)
2008 Endangered (EN)
2007 Endangered (EN)
2006 Endangered (EN)
2004 Endangered (EN)
2000 Endangered (EN)
1996 Endangered (EN)
1994 Endangered (EN)
1988 Threatened (T)

Geographic Range [top]

Range Description: Leptoptilos dubius was previously widespread and common across much of South and continental South-East Asia but declined dramatically during the first half of the 20th century (Birdlife International 2001). It is known to breed in Assam, India (at least 650-800 birds, or more [Choudhury 2000]), and at the Tonle Sap lake (c.75 pairs) and in Kulen Promtep Wildlife Sanctuary in the Northern Plains (c.15-20 pairs), Cambodia (T. Clements in litt. 2007). The species was reported to be breeding in Bihar, India, in 2004, and a small breeding population was discovered in the state on the Ganga and Kosi river floodplains in 2006 (Mishra and Mandal 2009). The population there appears to be increasing, with at least 156 estimated in 2008 and over 300 individuals in 2011, up from 78 in 2007 (Mishra and Mandal 2009, Kahn 2011). Recent records from Nepal, Bangladesh, and Thailand are presumed to refer to wanderers from India and Cambodia. Huge numbers once bred in Myanmar, but there have been just two recent reports from Meinmahla Kyun in 1998 and Kachin State in 2006 (G Chunkino in litt. 2006). There are no confirmed records from Laos in recent years. Breeding success in recent seasons has been extremely poor in Assam: the number of nests in colonies is declining sharply, but for unknown reasons (Goswami and Patar 2006). Despite this, large flocks of a few hundred birds are still noted around the city of Guwahati, which may provide feeding areas for around half of the species's world population (Choudhury 2008). Available data suggest that Cambodian populations declined heavily in the decades up to and including the 1990s. By 2001, several breeding sites recorded in the 1990s had been abandoned. Since 2001, protection measures at two known breeding sites (Prek Toal on the Tonle Sap and Kulen Promtep in Preah Vihear) have led to a stabilisation of national population declines and possible minor recoveries (Clements et al. 2007a, b).

Countries occurrence:
Bangladesh; Cambodia; India; Nepal; Thailand; Viet Nam
Possibly extinct:
Lao People's Democratic Republic; Myanmar
Regionally extinct:
Continuing decline in area of occupancy (AOO): Yes
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 96800
Continuing decline in extent of occurrence (EOO): Yes
Extreme fluctuations in extent of occurrence (EOO): No
Number of Locations: 11-100
Continuing decline in number of locations: Yes
Extreme fluctuations in the number of locations: No
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The total population is estimated to number 800-1,200 mature individuals, roughly equivalent to 1,200-1,800 individuals in total. This is based on estimates of 650-800 birds in Assam, India, plus 150-200 birds in Cambodia, as well as at least 156 birds in Bihar state, India, which may have dispersed from the Assam population.

Trend Justification:  This species's population is suspected to be decreasing very rapidly, in line with levels of direct exploitation and habitat destruction, particularly lowland deforestation and the felling of nest-trees, and drainage, conversion, pollution and over-exploitation of wetlands. Given the species's longevity, population trends are measured over a three-generation period of 45 years and hence the impacts have been severe.
Current Population Trend: Decreasing
Additional data:
Number of mature individuals: 800-1200 Continuing decline of mature individuals: Yes
Extreme fluctuations: No Population severely fragmented: No
No. of subpopulations: 1 Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: Yes
No. of individuals in largest subpopulation: 100

Habitat and Ecology [top]

Habitat and Ecology: While breeding in the dry season (October-May/June) it inhabits wetlands, nesting in tall trees, bamboo plantations 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 urban areas, 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.

Systems: Terrestrial; Freshwater
Continuing decline in area, extent and/or quality of habitat: Yes
Generation Length (years): 15
Movement patterns: Full Migrant
Congregatory: Congregatory (and dispersive)

Threats [top]

Major Threat(s): The key threats are direct exploitation, particularly at nesting colonies, habitat destruction, including some felling of nest-trees, and drainage, conversion, pollution and over-exploitation of wetlands. Additionally, the Indian population is threatened by reduced use of open rubbish dumps for the disposal of carcasses and foodstuffs. It has been suggested that recent nesting failures in Assam may be due to disease (Goswami and Patar 2006), which may have a negative impact upon the species in the future. Young birds may also become entangled in fishing nets and the species may suffer from the disturbance of arboreal animals, competition for nesting habitat from the Lesser Adjutant L. javanicus and the exacerbation of persecution levels owing to its pest status (Mishra and Mandal 2009). Poisoning of small wetlands to catch fish in the dry forests of northern and eastern Cambodia potentially poses a significant threat, and in Guwahati, India, pesticide use at open rubbish dumps where storks flocked to feed led to several mortalities in 2005.

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
In Assam, it occurs in Kaziranga, Manas and Dibru-Saikhowa National Parks. Since 1991, there have been conservation awareness programmes in Assam. In Nagaon district, Assam, Green Guards (a local NGO) had a project to protect nesting trees and rehabilitate chicks fallen from nests but this has now stopped (A. Choudhury in litt. 2012). In Cambodia, the breeding colony at Prek Toal is a core area of the Tonle Sap Biosphere Reserve. Greater Adjutants historically bred at other sites on the Tonle Sap, but these colonies were abandoned by 2001. Conservation actions to reduce chick and egg collection and other forms of disturbance to the breeding colony at Prek Toal have been in place since the late 1990s, with permanent teams of protectors employed since 2001. The small population in the Northern Plains is largely protected within Kulen Promtep Wildlife Sanctuary. Since 2001, c.95% of waterbird egg and chick collection has been prevented at Prek Toal. It is included in waterbird conservation awareness material in Laos and Cambodia.

Conservation Actions Proposed
Conduct further surveys in Cambodia, Myanmar and Bangladesh. Investigate seasonal movements and threats. Protect nesting and feeding-sites outside protected areas, and plant trees in suitable areas; the nest payment system in Cambodia may be a suitable model. Rewarding the owners of nesting trees may be a means to encourage pride in the conservation of the species (A.R. Rahmani in litt. 2012). Promote strict control of pesticide use around feeding areas. Continue and strengthen on-going conservation actions at the Prek Toal colony, Tonle Sap lake. Establish a wildlife protection office at Tonle Sap lake. Draft and enforce waterbird conservation legislation at Tonle Sap lake. Expand conservation awareness programmes and develop a structured captive breeding programme to support future reintroductions and population supplementation. Initiate a relief programme and promote alternative livelihoods to communities dependent on harvesting large waterbird colonies in Cambodia. Widely implement a policy of rescuing, rehabilitating and releasing chicks that fall from nests for natural reasons, such as during thunder storms (Singha and Rahmani 2006, Singha et al. 2006), and consider placing nets under nest-trees and conducting regular checks at colonies (Singha et al. 2006).

Citation: BirdLife International. 2013. Leptoptilos dubius. The IUCN Red List of Threatened Species 2013: e.T22697721A48055015. . Downloaded on 29 November 2015.
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