Justification of Red List Category
This stork is listed as Vulnerable because its population is suspected to be rapidly declining as a result of a variety of threats including hunting pressure, loss of nesting habitat, conversion and degradation of wetlands and agricultural changes and intensification. Conservation action is benefiting one key population in Cambodia, but rapid declines are likely to be ongoing elsewhere across the range.
A total population of 5,000 individuals was previously estimated by Hancock (1993), Choudhury (2000) and BirdLife International (2001). However, more extensive survey effort in recent years has led to upward revisions of some national totals: in particular the Cambodian population is now thought to number perhaps 1,500-3,500 pairs or 3,000-7,000 mature individuals (Goes 2013, S. Mahood in litt. 2013). Taking this total and perhaps 1,200 mature individuals in India, c.300 in Malaysia, 200-700 in Nepal, 250-400 individuals in Myanmar (Zöckler et al 2014; in litt) plus an unknown number in Indonesia (previously estimated at 2,000 individuals in 1993 but may have severely declined since), and assuming only very small numbers elsewhere, the global population probably numbers 5,500-10,000 mature individuals (roughly equating to 8,000-15,000 individuals).
This species's population is suspected to be declining rapidly, in line with increasing levels of felling of colony nest trees, drainage and conversion of wetland feeding areas, agricultural intensification, pesticide use, disturbance and large-scale development in coastal areas, but, most seriously, the persistent and unregulated harvesting of eggs and chicks from colonies.
Successes in parts of Cambodia are likely to be isolated and may be short-term (C. Robson in litt. 2013), and declines are predicted to be ongoing elsewhere in the country . In Indonesia, estimates in South Sumatra and Jambi provinces in 1984-1986 were 514 birds (388-620) and 272 (152-475) birds respectively, while surveys in these provinces in 2001-2004 estimated only 124 birds (30-318) and 7 birds (2-17) respectively (M. Iqbal in litt. 2013), suggesting that very rapid declines may have occurred on Sumatra.
Leptoptilos javanicus has an extensive range across South and South-East Asia (BirdLife International 2001). Substantial populations remain only in Cambodia (over 600 known pairs at Tonle Sap and the northern forests [Goes 2013] and a national total estimated in the range of 1,500-3,500 pairs [Bird et al. 2007, Goes 2013, S. Mahood in litt. 2013], with probably many more as recently as the early 1990s [R. Timmins in litt. 2013]), India (mostly in Assam, with c.2,000 birds [Choudhury 2000], West Bengal and Bihar, where 42 nests had breeding confirmed in 2004 [Mishra et al. 2004], but present across much of the country [Rahmani 2012]) and Indonesia (c.2,000 in 1993, the majority on Sumatra, but apparently far fewer since [M. Iqbal in litt. 2013]). There are smaller breeding populations in Nepal (300-1,000 birds, most in the east, with 188-268 birds in and around Royal Chitwan National Park in 2009 [C. Inskipp and H. S. Baral in litt. 2013]), Malaysia (c.500 individuals; Li et al. 2007), Sri Lanka, Bangladesh (18 adults at a colony in Thakurgaon district in 2012 and small numbers of non-breeders in the Sundarbans [Chowdhury and Sourav 2012]), Myanmar (regularly in most coastal mudflats with associated mangroves, coastal population estimated at 150-300 birds [Zöckler et al. 2014; Zöckler 2016], plus additional max. 100 at inland wetlands, such as Lake Indawgiy [Zöckler 2016]), Laos, Brunei, Vietnam and Thailand (very small numbers and possibly only one remaining breeding site [Rahmani 2012]). It has also been recorded in Bhutan (Choudhury 2005), but is thought to be extinct in China and in Singapore.
Formerly common and widespread, it has declined dramatically across its range and has been extirpated from many areas in recent decades owing a variety of threats including the persistent and unregulated harvesting of eggs and chicks at nesting colonies, loss of nesting trees and loss and degradation of wetland habitats. However, some populations at least seem to be relatively stable, e.g. numbers in the Matang Mangrove Forest, Malaysia have remained relatively constant for 20 years (Li et al. 2006), and numbers are increasing at Prek Toal, Cambodia owing to nest and colony protection (S. Mahood in litt. 2013; Visal and Mahood 2015). The global population may previously have been underestimated and may number c.5,500-10,000 mature individuals.
Inland, birds inhabit natural and human-modified wetlands, both open and forested. Coastal populations frequent mangroves and intertidal flats. It nests colonially in large trees, and historically on cliffs, often at traditional sites in or adjacent to wetlands. It utilises small wetlands within Asian dry forest, and can breed some distance from these; shrinking of pools during the dry season and limited availability can lead to overlap with human uses and resulting disturbance.
Several threats are contributing to its decline, with their relative importance varying across its range. The loss of nest-sites through the felling of colony nest-trees is a major threat, particularly in Assam - extensive nesting colonies outside protected areas in the 1990s recorded drastic declines owing to the cutting down of trees and drying up of some feeding sites (A. Choudhury in litt. 2012). In many areas, drainage and conversion of wetland feeding areas, agricultural intensification, increased pesticide use and disturbance, the collection of eggs and chicks and the hunting of adults are major threats, while the spread of invasive water hyacinth Eichhornia crassipes may be an additional threat at least in Nepal. A recent and very serious threat, recorded in Nepal and Cambodia, is the practice of poisoning pools to catch fish, which leads to incidental mortality of this species (Gyawali 2004, S. Browne in litt. 2005). Coastal populations are threatened by large-scale development, including aquaculture and the clearance of mangroves, while lowland wetlands are likely to be subject to a variety of threats including sea level rise, both directly but also through displacement of people, and conversion for plantation agriculture (J. W. Duckworth in litt. 2013). Key threats in Indonesia include the conversion of mangrove forest to fishponds and peatswamp forest to acacia plantations (M. Iqbal in litt. 2013). Longer term, massive dam projects in the Mekong catchment may threaten the persistence of Tonle Sap Great Lake (J. W. Duckworth in litt. 2013).
Conservation Actions Underway
Important nesting colonies are found in India at Kaziranga and Dibru-Saikhowa National Parks and Laokhowa Wildlife Sanctuary, Assam and D'Ering Sanctuary, Arunachal Pradesh. In Cambodia, the breeding colonies at Prek Toal and Moat Khla/Boeng Chhma are core areas in the Tonle Sap Biosphere Reserve. Conservation programmes at Prek Toal and in Preah Vihear have effectively protected colonies from egg and chick harvesting since the early 2000s (Goes 2013, S. Mahood in litt. 2013). It is included in conservation awareness material in Laos and Cambodia. In parts of Cambodia financial incentives have been offered to local residents for the protection of nests, resulting in much higher rates of nesting success (T. Evans in litt. 2006; Clements et al. 2013). It occurs in Chitwan and Bardia National Parks and in Koshi Tappu Wildlife Reserve in Nepal. Recent initiatives in Assam include nest surveys, a nest-tree replanting scheme and conservation awareness campaigns.
122-129 cm. Very large stork, dark grey-black above, white below, with naked head and neck. Non-breeders have mostly yellowish head and neck skin with vinous-tinged head sides and contrastingly pale forehead. Breeding males show coppery spots on median coverts, narrow whitish edges to lower scapulars, tertials and inner greater coverts and redder head sides. Juvenile is duller and less glossy above, with more down on head and neck. Similar spp. Greater Adjutant L. dubius has more massive bill, paler head sides, pendulous neck-pouch, pale grey greater coverts and tertials.
Text account compilers
Pilgrim, J., Taylor, J., Wheatley, H., Davison, G., Symes, A., Peet, N., Benstead, P., Tobias, J., Bird, J.
Goes, F., Inskipp, C., Zöckler, C., Chowdhury, S., Timmins, R.J., Baral, H., Mahood, S., Choudhury, A., Sourav, S., Robson, C., Gray, T., Browne, S., Choudhury, A., Duckworth, J.W., Iqbal, M., Clements, T., Evans, T.
BirdLife International (2023) Species factsheet: Leptoptilos javanicus. Downloaded from http://datazone.birdlife.org/species/factsheet/lesser-adjutant-leptoptilos-javanicus on 04/06/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 04/06/2023.