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Description |
Geographic Range [top]
Range Description: 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 in press] and a national total estimated withing the range 1,500-3,500 pairs [Bird et al. 2007, Goes in press, 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 (small numbers in many areas; Rahmani 2012), 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). The global population may previously have been underestimated and may number c.5,500-10,000 mature individuals
Countries occurrence:
Native:
Bangladesh; Brunei Darussalam; Cambodia; India; Indonesia; Lao Peoples Democratic Republic; Malaysia; Myanmar; Nepal; Sri Lanka; Thailand; Viet Nam
Possibly extinct:
China
Regionally extinct:
Singapore
Vagrant:
Bhutan
Additional data:
? Continuing decline in area of occupancy (AOO): Unknown
? Extreme fluctuations in area of occupancy (AOO): No ? Estimated extent of occurrence (EOO) - km2: 11300000
? 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: Unknown
? Extreme fluctuations in the number of locations: No
Range Map: Click here to open the map viewer and explore range.
Population [top]
Population: 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 in press, S. Mahood in litt. 2013). Taking this total and perhaps 1,200 mature individuals in India, c.300 in Malaysia and 200-700 in Nepal, 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).
Trend Justification: This speciess 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.
Current Population Trend: Decreasing
Additional data:
? Number of mature individuals: 5500-10000 ? Continuing decline of mature individuals: Unknown
? Extreme fluctuations: No ? Population severely fragmented: No
? No. of subpopulations: 2-100 ? Continuing decline in subpopulations: Unknown
? Extreme fluctuations in subpopulations: No ? All individuals in one subpopulation: No
? No. of individuals in largest subpopulation: 1-89
Habitat and Ecology [top]
Habitat and Ecology: 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.
Systems: Terrestrial; Freshwater; Marine
Continuing decline in area, extent and/or quality of habitat: Yes
Generation Length (years): 16.1
Movement patterns: Full Migrant
Congregatory: Congregatory (and dispersive)
Threats [top]
Major Threat(s): 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 [top]
Conservation Actions: Conservation Actions Underway
Important nesting colonies are found in India at Kaziranga and Dibru-Saikhowa National Parks and Laokhowa Wildlife Sanctuary, Assam and DEring 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 in press, 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 by conservation organisations if nesting attempts at known waterbird colonies are not disrupted (T. Evans in litt. 2006). 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.
Conservation Actions Proposed
Monitor key colonies, and conduct searches for others. Protect nesting colonies outside protected areas. Promote control of pesticide use around feeding areas. Establish a wildlife protection office at Tonle Sap lake. Investigate alternative livelihoods for people dependent on harvesting eggs and chicks. Draft and enforce laws prohibiting hunting, trapping and poisoning. Expand conservation awareness programmes. Research the speciess use of and dependence upon agricultural landscapes including rice paddies (Baral 2005). List the species in Nepal under the National Parks and Wildlife Conservation Act (Gyawali 2004, Baral 2005). Protect key sites in Nepal.
Citation: BirdLife International. 2016. Leptoptilos javanicus. The IUCN Red List of Threatened Species 2016: e.T22697713A93632546. http://dx.doi.org/10.2305/IUCN.UK.2016-3.RLTS.T22697713A93632546.en. Downloaded on 10 May 2017.
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