Archived 2012-2013 topics: Lesser Adjutant (Leptoptilos javanicus): downlist to Near Threatened?

BirdLife species factsheet for Lesser Adjutant Lesser Adjutant Leptoptilos javanicus has an extensive range across South and South-East Asia (BirdLife International 2001). It is currently listed as Vulnerable under criterion A2cd+3cd+4cd of the IUCN Red List because its population was suspected to be rapidly declining at a rate of ≥30% over three generations (48 years in this species), 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. The most serious threat, however, is the persistent and unregulated harvesting of eggs and chicks from colonies. 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. 2007). The current population estimate is 5,000 birds; however, an increase in survey effort across much of the region has revised many national totals upwards. Analysis of Cambodian records estimated a national population of c.1,870 pairs (Bird et al. 2007); precautionary interpretation of this figure suggested the previous national estimate of 1,000 individuals should be revised upwards considerably to 2,500-4,000 individuals. The species is said to have definitely benefited from conservation action in Cambodia, ensuring colony protection from egg and chick harvesting and its population could easily be 50% to 100% larger than the current estimate (Goes in prep. 2012). Therefore, overall the global population may be considerably larger than previous estimates (approximately 4,300 – 5,300 mature individuals or more). In addition, calculating the rate of decline for a widespread species which occurs in relatively low numbers is difficult (S. Mahood in litt. 2012), and so the rate of decline may be lower than previously thought. If there is sufficient evidence to suggest that the rate of decline is not more than 30% over three generations, this species would no longer qualify as Vulnerable under the A criterion and would warrant downlisting to Near Threatened. Nevertheless, little is known about the nesting success of the Lesser Adjutant and in long-lived species such as this, populations can remain stable for long periods even when breeding has ceased to be a profitable activity (S. Mahood in litt. 2012). Information is requested on this species’s population trends, population size and breeding success. Any further comments on the proposed downlisting are welcome. References: Bird, J. P., Mulligan, B. and Gilroy, J. (2007) Cambodia ornithological expedition 2006. Li, Z.W.D., Yeap, C. A. and Kumar, K. (2007). Surveys of coastal waterbirds and wetlands in Malaysia, 2004-2006. In: Li, Z. W. D. and Ounsted, R. (ed.), The status of coastal waterbirds and wetlands in Southeast Asia: results of waterbird surveys in Malaysia (2004-2006) and Thailand and Myanmar (2006), pp. 1-40. Wetlands Internationa: Kuala Lumpur.

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10 Responses to Archived 2012-2013 topics: Lesser Adjutant (Leptoptilos javanicus): downlist to Near Threatened?

  1. Tom Gray says:

    Lesser adjutant is the most frequently recorded large waterbird in the decidious dipterocarp forests of eastern Cambodia.
    However given the pervasive and accelerating threats to this habitat from unregulated economic and social land concessions I believe it is sensibly precautionary to predict minimum future 30% decline (at least in Cambodia) in next three generations. Given the species’ scarcity in the degraded DDF of southern Laos, Vietnam, Thailand together with the uncertainity for the species’ prospects in Cambodia down-listing would, in my opinion, not be sensible.

  2. Simon Mahood says:

    As S. Mahood said in 2012 “In addition, calculating the rate of decline for a widespread species which occurs in relatively low numbers is difficult…” so just as you tagged on that the rate might be lower than previously thought, it might also be higher, or the same.

    Lesser Adjutant has benefited from conservation action in Cambodia, both as a result of nest protection in the deciduous dipterocarp forest and colony protection at Prek Toal. In the latter the population is growing and currently numbers some 350 pairs (this represents c. 10% of the Cambodian population). However, overall the population is still declining at a rate equal to or above the rate of forest degradation (important because degradation = people in the forest = hunting) and loss.

    Habitat conversion continues at an incredible pace in Cambodia, and, since this country supports most of the global population it would be wise to assume that the current and future rate of decline exceeds 30% over three generations. I do not support downlisting.

  3. Current status and distribution of the Lesser Adjutant in Bangladesh is summarized here: Chowdhury, S.U. & Sourav, S.H.M. 2012.Discovery of a Lesser Adjutant Leptoptilos javanicus breeding colony in Bangladesh. BirdingAsia 17: 56.

  4. Joe Taylor says:

    The following comments were received from Muhammad Iqbal on 4 April 2013:

    Sumatra is one important habitat for this species. I am afraid that this bird decline in Sumatra caused by loss breeding areas; convertion mangrove forest as fish pond and peatswamp forest as Acacia plantation. I will check the number in the future to make comparison.

  5. With a 48-year window for assessment, and looking at the battery of threats facing lowland areas well supplied with wetlands, from sea-level rise (not just direct loss of adjutant areas, but displacement of people through loss of farmland to look for new areas) to plantation agriculture, a proposal to change from VU to NT would have to be very well justified. I don’t see any evidence above that it is, particularly not for likely future population trends. Moreover, few people nowadays probably have any perception of how common this species may well have been 50 years ago (i.e. start of window for past decline to meet 30% or more) – anyone who has seen the Wharton Kouprey film cannot fail to have been taken aback at the large number of large waterbirds in the background scenery. The perception that there are actually rather more now than any one thought, and that in one area declines have been reversed, needs to be seen in a time window far longer than with most SE Asian birds. I think this is a good example of the phenomenon labelled in an issue of Oryx a few years ago as “less and less-great expectations’, because there are no people around able to tell us just how badly this species is doing over the last 3 generations. The fact that its rate of decline in the last 20 years (a typical average assessment period for birds) probably does not approach VU may be instilling a misleading sense of security here. The Tonle Sap colony success needs to be replicated a good deal more widely if the global population trend is to be materially affected. Besides, who feels they can safely predict whether the Great Lake of Tonle Sap will even exist in 2060, given current serious proposals for Mekong catchment megadams and the Great Lake’s dependence on high enough wet-season Mekong levels to reverse the (river) Tonle Sap flow and refill the Great Lake every year. If asked which direction the category should go from VU I’d say EN more likely than NT!

  6. Data derived from Silvius (1988) from South Sumatra and Jambi province show average number during 1984-1986: in South Sumatra is 514 birds (lowest number 388 birds and highest number 620 birds) and in Jambi province is 272 birds (lowest number 152 birds and highest number 475 birds). Recent data from Wetland International (2004) in the east coast South Sumatra during 2001-2004 show the average number is 124 birds (lowest number 30 birds and highest number 318 birds) and in the east coast Jambi during 2002 show the average number is 7 birds (lowest number 17 birds and highest number 2 birds). Refer to the datas above, the declining of Lesser Adjutant in South Sumatra is approximately 76% and in Jambi province up to 97%. I agree if the Lesser Adjutant (at least in Sumatra or Greater Sunda), nearly from VU to EN than VU to NT.

    Silvius, M. J. (1988) On the importance of Sumatra’s east coast for waterbirds, with notes on the Asian Dowitcher Limnodromus semipalmatus. Kukila 3 (3–4): 117–137.

    Wetlands International Indonesia Programme (2004) Laporan-laporan Teknis Proyek Konservasi Terpadu Lahan Basah Pesisir Pesisi Berbak Sembilang. CD-ROM. Palembang: Wetlands International (in

  7. Craig Robson says:

    It should certainly not be delisted. Its overall numbers are sure to continue in decline. The success in Cambodia is isolated and may only be short-term, as suggested above.

  8. R. J. Timmins says:

    I think this is a great case of extremely blinkered thinking. People looking at the best sites and saying everything is okay. The Cambodian population certainly ranks as EN if not CR. Part of the problem is that no one has ever properly considered the recent start point of the Cambodian population. My own feeling is that in the early 90′s there was probably more than 10,000 breeding birds in the dry-forests alone (e.g. excluding those around the Tonle Sap. That adult population may still be well over 5,000 birds, but except in a few localised places where NGOs are protecting nests, breeding success is low and adults are certainly declining. The Tonle Sap population is doing well, but it’s still a minority of the potential breeders in Cambodia. The Cambodian lowlands are changing (for the worse) so fast, that it’s hard to see even a quarter of the current population making it through the next decade or so. As to detecting declines, it’s hard when everyone is focused on NGO protected landscapes (e.g. not the place to be loking for a decline), and even in these would a 50% decline be noticed given that birds are still seen daily and the observers in the 90s haven’t been back in recent years? My guess; if I revisited many of these areas I’d probably notice a difference.

  9. Frederic Goes says:

    I agree with most comments that it shall definitely not be downlisted, at least based on the Cambodian situation. I also recognise that we lack the hindsight to properly quantify the decline for such long-lived species, as there are no data at all from Cambodia during 1970 to 1990! The listing as NT in Cambodia is therefore inferred from a shorter window, and linked with partial (but significant) population recovery following nest protection. Summary Cambodian status and conservation discussion below (excerpt from the checklist in press).

    Lesser Adjutant
    A fairly common and widespread resident in various freshwater and coastal wetlands. In lowlands and lower hills, but recorded once at 900m at Dak Dam (Mondolkiri). The most wide-ranging and versatile large waterbird, occurring in swamp forest, dry deciduous and semi-evergreen forests, grasslands, reservoirs, rivers and floodplain marshes, mudflats, mangroves and wet rice fields. Recorded on a coastal island, as well as on the upper Mekong river channel mosaic. Present throughout the southwest lowland, the Tonle Sap floodplain and the forested northern half of the country where it is the most frequently encountered large waterbird. Local non-breeding visitor in the southeast (regular at one site). Most of the Tonle Sap population disperses throughout the country during the wet season, while parts of forest populations might visit the Tonle Sap during the dry season. Usually in small flocks, but large congregations occasionally noted in the floodplain grasslands. // Conservation: Although the species declined during the latter half of the 20th century in the Kingdom, it is still fairly numerous and widespread. Data from patrolling teams in Preah Vihear recorded the species on 2,018 occasions between July 2005 and December 2006, a far higher rate than any other monitored species (WCS 2007). Moreover, analysis including population extrapolations suggests that the sub-regional population may be underestimated (Timmins & Clements 2006b). Tonle Sap and the northern forests support over 600 known pairs, but are likely to hold over 1,000 pairs considering that (i) not all nests are visible and thus counted at Prek Toal, (ii) small, unmonitored colonies likely persist elsewhere on the Tonle Sap floodplain, and (iii) only part of vast area of suitable habitat is monitored in Preah Vihear. This must surely be supplemented by an unknown number of small colonies scattered throughout the vast northeastern and southwestern lowland forests. The Cambodian population could therefore easily approach 1,500 pairs and taking into account non-breeding immatures, Cambodia may actually support as many as 8,000–10,000 birds. Conservation programmes at Prek Toal and in Preah Vihear have effectively protected colonies from egg and chick harvesting since the early 2000′s. Nevertheless, the species’ large size and colonial breeding behaviour put it at risk of persecution in areas lacking on the ground protection, as demonstrated by the very low breeding success at unprotected colonies in Preah Vihear (Clements et al. 2013). Even at Prek Toal, two chicks confiscated from villagers in May 2011 indicate that the species is still not completely safe (Evans & Goes 2011c). As the species’ current status heavily depends on continued colony protection programmes, it is listed as nationally Near-Threatened.

    Lesser Adjutant has been assessed as Vulnerable in Nepal based on the criteria A2cde and C2a(i) in a draft species account prepared for the Nepal bird Red Data Book. This draft assessment was upheld at the October 2012 workshop held to discuss over 240 draft Nepal species accounts. The following text is extracted from the full Lesser Adjutant species account which is available for download from the front page of Himalayan Nature: A distribution map showing pre- and post-1990 distribution is also available here.

    STATUS AND POPULATION The species is a now local resident in the terai, mainly occurring in the east. Recently it has been recorded at more localities in the west, probably because of better recording. However, numbers appear to have declined in the east, although the main population is still concentrated there. The population is estimated to be less than 1000 birds.

    THREATS Lesser Adjutant faces a wide range of threats, chiefly habitat loss and alteration, disturbance, hunting for food and medicinal purposes and development. It is also threatened by poisoning of wetlands to capture fish, water pollution by factory effluents and the invasive spread of Water Hyacinth. Other threats are changes in agricultural practices from paddy fields to cash crops which causes a reduction in feeding areas and pesticide use in agricultural lands (the extent of which is currently unknown). The drying out of wetlands are additional threats in Sukla Phanta Wildlife Reserve and Bardia National Park as the species is confined to these protected areas in the dry season when adjacent paddy fields are dry.
    The species chiefly feeds outside of protected areas in agricultural lands, mainly in flooded paddy fields. In the east it also mainly nests at unprotected sites in the east e.g. Urlabari Important Bird Area, Morang District and Dharan forests Important Bird Area.

    We strongly support maintaining Lesser Adjutant as globally Vulnerable. In Nepal although it regularly occurs in three protected areas (Chitwan and Bardia National Parks and in Koshi Tappu Wildlife Reserve), over 50% of known nests are outside of the protected areas and it chiefly feeds outside of protected areas.

    Carol Inskipp and Hem Sagar Baral

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