| Citation |
BirdLife International. 2017. Asarcornis scutulata (amended version of 2016 assessment). The IUCN Red List of Threatened Species 2017: e.T22680064A110103586. https://dx.doi.org/10.2305/IUCN.UK.2017-1.RLTS.T22680064A110103586.en. Downloaded on 18 June 2020. |
Description |
JUSTIFICATION
This forest duck is listed as Endangered because it has a very small and fragmented population which is undergoing a very rapid and continuing decline as a result of the loss of and disturbance to riverine habitats.
RANGE DESCRIPTION
Asarcornis scutulata was historically widely distributed from north-eastern India and Bangladesh, through South-East Asia to Java and Sumatra, Indonesia (Green et al. 2005). It has undergone a dramatic decline, such that its population is now estimated at c.1,000 individuals, comprising c.200 in Laos, Thailand, Vietnam and Cambodia, c.150 on Sumatra, Indonesia, c.450 in India (Choudhury 2000) and Bangladesh (A. Choudhury in litt. 2007) and in the "low hundreds" in Myanmar (J. C. Eames in litt. 2007) following the identification of a significant population numbering tens of individuals in the proposed Hukaung Tiger Reserve. It has also recently been recorded in Bhutan (Choudhury 2007). It continues to decline throughout its range, and is probably extinct in Malaysia. The only recent records from Vietnam are from watercourses in dry dipterocarp forest in Yok Don NP, where it is rare but probably under-recorded (Eames in litt. 2012). It is likely to be extirpated elsewhere due to widespread forest and wetland destruction. There are no confirmed recent records from Laos, however, a few birds probably survive in the Nam Theun catchment (W. Duckworth in litt. 2012). In Myanmar it is locally common on ox-bow lakes within the Chindwin basin (Tordoff et al. 2007). In India, it has been recorded from Arunachal Pradesh, Assam, Meghalaya, Nagaland and Manipur (no recent report), with unconfirmed reports from Tripura and Mizoram. Its current distribution is chiefly in the eastern lowlands of Assam and Arunachal Pradesh (A. Rahmani in litt. 2012).
DESCRIPTION
There has not been a comprehensive analysis of recent records, but estimates of c.450 in India (A. Choudhury in litt. 2007), (although it may be lower than this estimate [H. Yahya in litt. 2016]) low hundreds in Myanmar and c.100 in Cambodia (J. C. Eames in litt. 2007) combined with an earlier estimate of 150 in Indonesia suggest that the speciess population may precautionarily be considered to lie within the band 250-999 mature individuals. This equates to 375-1,499 individuals in total, rounded here to 350-1,500 individuals.
Trend Justification: This speciess population is suspected to have decreased very rapidly owing to the widespread loss, degradation and disturbance of lowland riverine habitats. Resultant small and fragmented populations are susceptible to hunting - opportunistic collection of eggs and chicks - and other stochastic events.
HABITAT AND ECOLOGY
Usually found alone or in small groups, the species is most easy to see at dawn and dusk when moving between daytime roosts and the speciess feeding sites (Green 1993a, Green et al. 2005). It inhabits stagnant or slow-flowing natural and artificial wetlands, within or adjacent to evergreen, deciduous or swamp forests, on which it depends for roosting and nesting, usually in tree-holes. Although lowlands (below c.200 m) provide optimum habitat, it occurs up to 1,400 m, especially on plateaux supporting sluggish perennial rivers and pools. It has been described as ominvorous (Green et al. 2005), with pondweed, small fish, aquatic snails, spiders and insects being consumed regularly (Green 1993). Breeding season may vary across its range so that hatching coincides with the early wet season, when food supply may be more favourable (Green et al. 2005). The clutch size can vary to quite an extent with a range of 6-13 in captivity and 2-12 in the wild (Mackenzie and Kear 1976, Green 1993a, Green et al. 2005).
THREATS
Its decline is largely attributable to the destruction, degradation and disturbance of riverine (e.g. wetland drainage [Green 1993b]) and forest habitats that this species is dependent on, including the inappropriate management of forests (e.g. forest burning during the dry season [see Green 1993b]). It may be particularly susceptible to loss of large trees with nesting holes (W. Duckworth in litt. 2006). The resultant small, fragmented populations are vulnerable to extinction from stochastic environmental events, loss of genetic variability, disturbance, hunting and collection of eggs and chicks for food or pets. While trade may be more of a local threat to the species, off-take for hunting, which goes relatively unreported, is a far more serious issue (Green 1993b). Hydro-power development, and pollution (see Green 1993b) are other more localised threats.
CONSERVATION ACTIONS
Conservation Actions Underway
CITES Appendix I. The Wildfowl and Wetlands Trust produced, and implements, an action plan for the species. In 1993, 21 protected areas were known to support populations. Dibru-Saikhowa National Park and Dihing-Patkai Wildlife Sanctuary, both in Assam, were established because of its importance for this species, while a significant population is in Nameri National Park (see Das and Deori 2011, A. Choudhury in litt. 2016). Sylvan Heights owns a number of captive breeding birds in the US however, few, if any, reintroduction attempts have been made (Kivi 2010, Sylvan Heights Bird Park). Captive breeding programmes have also taken place at Slimbridge (UK), Bardobi Tea Estate (Assam) and Miao Zoo (Arunachal Pradesh), but the eggs and chicks developed Tuberculosis and so no reintroduction took place (A. J. Green and H. Yahya in litt. 2016). Conservation awareness materials depicting it have been widely distributed in Laos and Cambodia.
Conservation Actions Proposed
Conduct further surveys to clarify its distribution and status. Instigate regular monitoring of selected key populations. Promote strict enforcement of hunting regulations and minimise encroachment, disturbance and habitat degradation in all protected areas supporting populations. Campaign for increased protection of peat-swamp forest in Sumatra and moist lowland forest in other range states (A. J. Green in litt. 2016), and provide more effective protection to reduce illegal activities in habitats where this species occurs (Yahya 1994a,b). Campaign against pesticide and oil pollution at key sites in north-east India. Promote more widespread conservation awareness campaigns in and around key protected areas. Rapidly introduce the measures outlined above in newly discovered strongholds, e.g. northern Myanmar. Ensure that captive breeding centres maintain healthy populations of this species, and ensure that diseased individuals are not able to escape and thus potentially spread disease in wild populations (see Yahya 1994a,b). |
