Justification of Red List Category
This species has been uplisted to Near Threatened on the basis that it is expected to undergo a moderately rapid population decline over the next three generations owing to human pressures on riverine ecosystems and the construction of dams.
The population size is difficult to determine. Waterbird Population Estimates provides an estimated population size of 1-25,000 individuals for the period 1987-1991 (Wetlands International 2016). The population may possibly number no more than 15,000 individuals (Wiersma and Kirwan 2016). The population is therefore placed in the band 10,000-19,999 mature individuals roughly equivalent to 15,000-29,999 individuals.
The current population trend is difficult to determine because of uncertainty over the extent of threats to the species; however, it is expected to undergo a moderately rapid population decline overall during the next three generations, owing to the impacts of human pressures on riverine ecosystems and multiple dam construction projects. In Cambodia the population has undergone declines; in Sesan the population decreased from 223 birds in 1998 to 102 in 2003 and 60 birds (river survey length slightly shorter than in previous surveys) in 2010 (Goes 2014). Breeding success in all populations in Cambodia is reportedly low owing to multiple human-related threats (Goes 2014). Construction of the Don Sahong Mekong-mainstream dam in southern Laos could compound could contribute to further population declines (Goes 2014).
This species occurs in southern China, much of South-East Asia, and the northern Indian Subcontinent (Chandler 2009), including Nepal, Bhutan, India, Bangladesh, Myanmar, Thailand, Cambodia, Laos and Vietnam. This species generally occurs at low densities throughout most of its range (Li et al. 2009), and there are several threats that are thought to be driving at least regional or local declines, but the population is expected to go into overall decline as impacts intensify and become more widespread. In Cambodia the species is considered extinct in the south-west and is now restricted to the upper Mekong and its tributaries (Goes 2014).
It inhabits larger rivers and lakes (Chandler 2009), preferring wide, slow-moving rivers with sand or gravel bars and islands (Duckworth et al. 1998). It also uses reservoirs (F. Goes in litt. 2016).
In southern Thailand, the species is threatened by the casual off-take of eggs and chicks, and potentially by future agricultural intensification in some areas (Wells 1999). Collection of eggs and chicks takes place throughout south-east Asia (W. Duckworth in litt. 2016). It is also threatened by incidental disturbance caused by people, livestock and dogs, and is potentially seriously impacted by the multitude of hydroelectric dam projects completed, underway and planned on large rivers in its range, which threaten to alter flow regimes (Thewlis et al. 1998, Duckworth et al. 1998, 2002, Duckworth and Timmins 2013, F. Goes in litt. 2011). Whilst dam construction is likely to have negative impacts on the species, it is difficult to predict the timeframe of these impacts owing to uncertainty around when and if specific dams will be built (A. Claassen in litt. 2016). In Cambodia, the species is threatened by opportunistic harvesting of eggs by local people, nest predation by crows, rodents, and domestic dogs, trampling of nests by domestic water buffalo, disturbance by people and domestic animals, and flooding of nests and breeding habitat by hydroelectric dams (Claassen 2004, Claassen et al., in press). Populations on the Cambodian stretches of the Sesan and Sekong rivers are threatened by upstream hydropower dams located in Vietnam and Laos. Additionally, there is now a hydropower dam being constructed in Cambodia at the confluence of the Sesan and Srepok rivers which will destroy habitat in the reservoir area, and water releases from the dam will potentially flood nests located downstream. Populations along these rivers will be negatively affected by these developments (F. Goes in litt. 2011, A. Claassen in litt. 2016). The threats of disturbance and hunting, in Laos at least, are exacerbated by the tendency for both V. duvaucelii and human settlers to select the same rivers, although the numbers of the species and frequency of villages are inversely correlated, which appears to confirm that there are some negative impacts from human activities (Duckworth et al. 1998). Prior to construction of the Nam Theun 2 hydropower dam on the Nakai Plateau in central Laos, the River Lapwing population experienced low reproductive success due to disturbance (and probable egg harvesting) by local fishermen; the lapwing population likely completely disappeared once the plateau was converted into a reservoir following completion of the Nam Theun 2 dam (A. Claassen in litt. 2016). Along the Sangu river in Bangladesh, which may harbour all or most of the country's population of V. duvaucelii, the species is subject to on-going hunting pressure, and there is no evidence of successful breeding along surveyed stretches, probably owing to the frequenting of sandbars by people, dogs and corvids (S. Mahood in litt. 2012).
Conservationa Actions Underway
In Cambodia, nest protection (consisting of education and employing local people as nest guards) is being implemented on the Sekong and Sesan rivers by the Royal University of Phnom Penh (A. Claassen in litt. 2016). Some of its habitat has been protected. In Cambodia it is considered Threatened, in Laos it is considered At Risk and in Thailand it it considered Vulnerable (Goes 2014). In Nepal the species was recently assessed as Near Threatened (Inskipp et al. 2016).
Conservation Actions Proposed
Carry out regular surveys to monitor population trends throughout its range. Quantify the severity and impact of threats across its range. Carry out awareness-raising activities to alleviate human pressures on riverine ecosystems, and lobby against high-impact dam projects. Increase the area of suitable habitat that receives effective protection. Establish protected areas for sandbar-nesting species along the Cambodian Mekong, protecting the species from disturbance, predation and harvesting during the breeding season (F. Goes in litt. 2016). Implement more direct nest protection schemes and initiatives to prevent disturbance (Goes 2014).
Text account compilers
Butchart, S., Ekstrom, J., Taylor, J., Ashpole, J
Mahood, S., Goes, F., Thewlis, R., Praveen, J., Claassen, A., Duckworth, W.
BirdLife International (2019) Species factsheet: Vanellus duvaucelii. Downloaded from http://www.birdlife.org on 12/12/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 12/12/2019.