| Citation |
BirdLife International 2018. Aythya baeri (amended version of 2017 assessment). The IUCN Red List of Threatened Species 2018: e.T22680384A129599398. http://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T22680384A129599398.en. Downloaded on 25 September 2019. |
Description |
RANGE DESCRIPTION
The species breeds from the Amur and Ussuri basins in Russia southwards to the central and lower Yangtze floodplain in central-eastern China. It winters mainly in central-eastern China, though occasionally peak concentrations occur further north when winter conditions allow (e.g. Shandong province). Seemingly, few now winter outside China; the largest flocks since 2012 have been observed in Bangladesh (recent maximum winter total of only 17 individuals, down from 1,000–2,000 individuals [Chowdhury et al. 2012]; and only 5 individuals seen at Hakaluki Haor in January 2016 [S. Chowdhury in litt. 2016]), Myanmar (up to 12 individuals in Jan-April 2016 [Aung et al. 2016]), Thailand (3 at Bung Boraphet in 2015/16 [Bird Conservation Society of Thailand per R. Hearn in litt. 2016]) and India (3 in Assam in 2014/15 [R. Hearn in litt. 2016]). Other occasional occurrences of wintering or passage individual birds or small flocks have been recorded since 2012 in: Japan, South Korea, Hong Kong (China), Mongolia, and the Philippines, where only four records exist, the most recent from January 2015 when a male was found in Candaba (R. Hutchinson in litt. 2015, Ramos 2015). Thus, its distribution is now highly localised, with just a handful of sites used regularly either during the breeding season or winter. However, birds may still occur in any season at sites or in countries where they have not been recently recorded, including: North Korea, Taiwan (China), Nepal, Bhutan, Lao PDR (only one confirmed record [J. Tordoff in litt. 2007]), and Viet Nam (very rare in recent years [J. Tordoff in litt. 2007]).
Declines in the breeding range appear to have been substantial in northern China with no confirmed breeding at any sites north of Beijing since at least 2010. However, some breeding sites in this region are likely to remain unknown as winter counts of the population are larger than the number of birds that can currently be accounted for during the breeding season (Hearn 2015a). A few observations support this assertion, including 52 reported at Xingkai Lake (Lake Khanka) in March 2014 (T. Townshend per R. Hearn in litt. 2016). In neighbouring Russia there are also no confirmed breeding records in recent years, though it is suspected from at least two sites; Khasan wetlands (Solovyeva et al. 2013 per R. Hearn in litt. 2016) and Muraviovka Park (Heim et al. 2013). South of Beijing, several important breeding sites have been discovered since 2012. The most important is in Hebei Province (Townshend 2014) where 20-30 birds are seen annually in spring (R. Hearn in litt. 2016) and larger post-breeding flocks of up to 65 individuals (August 2014) (T. Townshend in litt. 2014). Two breeding sites as far south as the Yangtze floodplain were discovered in 2014 and 2016; one in Hubei (Lu et al. 2015) and another in Jiangxi (L. Wu per R. Hearn in litt. 2016). One female bird was recorded over a period of several weeks at Muraviovka Park, Russia in July 2013 but direct evidence of breeding or nesting was not found and the area flooded soon afterwards (Heim et al. 2013). Other possible breeding sites have been located in Shandong Province, China (N. Moores in litt. 2014) and Henan Province (X. Tao per R. Hearn in litt. 2016). Two individuals observed over winter 2012–2013 in China and South Korea were likely to have been first winter birds (Hearn et al. 2013).
A drastic decline and range contraction has also occurred in the speciess wintering range, with the species ceasing to winter in regular numbers at any site outside of mainland China as of winter 2010/11. Within China, the species has declined rapidly too (in the middle and lower Yangtze floodplain counts reduced 99% between 1986-93 and 2010-11 [Wang et al. 2017]), and site use is sporadic. Recent peak winter counts have come from several locations, and none in more than a single year. In 2014/15, a peak count of 84 was recorded at Tai Bai Hu, Shandong Province (S. Chan in litt. 2014), but none were there in 2015/16, when a peak count of c.200 was recorded at Jiujiang, Jiangxi Province (L. Wu per R. Hearn in litt. 2016). Other large counts include 68 at Chong Hu, Hubei Province, in January 2015 and 40 at Chenyao Hu, Anhui Province, in February 2014. Observations of the species migrating along the Hebei coast, China, have reduced considerably in more recent years (J. Hornskov in litt. 2009). The total population is now likely to be fewer than 1,000 individuals (Wang et al. 2012).
DESCRIPTION
Wang et al. (2012) stated that the global population is likely less than 1,000 individuals and could be much less than this, and so it is placed in the band 250-999 individuals, equating to 167-666 mature individuals, rounded here to 150-700 mature individuals, which now potentially can be considered to be in one sub-populations (R. Hearn in litt. 2016).
Trend Justification: An extremely rapid population decline over the last three generations is estimated from numbers recorded on wintering and breeding grounds, as well as migration routes on the Hebei Coast, China (J. Hornskov in litt. 2005), and is thought to be caused by on-going hunting and habitat degradation; hence, the decline is expected to continue at this rate, though the reasons for the decline are not fully understood (R. Hearn in litt. 2016).
HABITAT AND ECOLOGY
It breeds around lakes and other freshwater habitats (including artificial habitats such as fishponds) with rich aquatic vegetation, typically but not exclusively in dense grass or flooded tussock/shrubby meadows. In Liaoning, China, it is usually found in coastal wetlands with dense vegetation, or potentially on rivers and ponds surrounded by forest. The nest is built on a tussock or under shrubs, sometimes floating, and occasionally amongst branches. In winter, it occurs on freshwater lakes and reservoirs.
THREATS
Little quantified data exists on the causes of decline of Baer’s Pochard. However, the principal threats are thought to be habitat loss and degradation, particularly from drainage and rice cultivation, and unsustainable exploitation for food, both of fledged birds and eggs (R. Hearn in litt. 2016). It seems likely that the long-term decline was caused predominantly by habitat loss, and the apparent recent exacerbation of the decline is due to over-harvesting of what had already become a small and localised population (R. Hearn in litt. 2016).
Hearn (2015b) assessed threats the species to include habitat loss and degradation, unsustainable harvesting, disturbance and recreation, bycatch in fishing nets, hybridisation, and pesticides and fertilisers.
Habitat loss and degradation is probably greatest in the breeding areas, particularly in China north of Beijing where extensive wetland loss has occurred since the 1950s primarily as a result of agricultural development. For instance in Heilongjiang, wetland loss for farming (predominantly rice production) has exceeded 70% in some areas (Liu et al. 2005) and a similar pattern has occurred elsewhere in northeast China, e.g. in the Songnen Plain, Jilin Province (Wang et al. 2011). Recently discovered breeding sites at fishponds in the Yangtze floodplain are under threat from changes in use and drainage, e.g. at Huangpi (near Wuhan, Hubei) around half of the habitat used by breeding Baer’s Pochard in 2014 was lost before the 2015 breeding season (Hearn 2015a, Lu et al. 2015). Wintering sites are also under threat from habitat loss and degradation. Large-scale habitat alteration has taken place in the Yangtze floodplain due to conversion of wetlands for agriculture, resulting in a large area of natural wetland being lost, estimated to be 62% between the 1950s and the 1980s. Candaba Swamp in the Philippines where the species has been recorded in winter as a vagrant is under imminent threat of land conversion (Roberts 2015).
Unsustainable harvesting, both trapping and poisoning of birds and the collection of eggs, is a major threat faced by many Asian waterbirds. The traditional harvesting of wild animals, including birds, has increased dramatically in the past decade, and is now a major cause of decline for some wild fauna, probably including some waterbird species. Although the scale of this is currently hard to quantify for Baer’s Pochard (as no wide-ranging quantitative assessments have been undertaken), it could be significant, particularly in China where illegal poisoning and trapping of waterbirds is widespread, indiscriminate (MaMing et al. 2012) and continuing to worsen (MaMing per R. Hearn in litt. 2016), and the scale of egg collection, whilst unknown, is also probably widespread and highly organised and is also thought to be concentrated in northeast China, within the breeding range of Baer’s Pochard (MaMing per R. Hearn in litt. 2016). Incidents of the use of poisoned baits have also been recorded at wintering locations for Baers Pochard in Bangladesh which have the potential to cause significant mortality from a single incident (Chowdhury et al. 2012).
Additionally, in several cases, the loss of populations from former important areas have been preceded by low water levels or complete drying up of water bodies (e.g. the loss of the breeding population at Xianghai Reserve and the wintering population at Baiquan wetlands in Wuhan [J. Hornskov in litt. 2005, S. Chowdhury in litt. 2010, W. Xin, C. Lei, L. Jinyu and T. Fox in litt. 2012]). Development for tourism and recreational watersports pose a threat to the speciess habitat (Townshend 2014), particularly at Hengshui Hu, Henan, China (one of the most important known breeding sites) (R. Hearn in litt. 2016). Incidents of hunting by the use of poisoned baits have been recorded at wintering locations for Baers Pochard in Bangladesh. which have the potential to cause significant mortality from a single incident (Chowdhury et al. 2012). Hybridisation with Ferruginous Duck, Aythya nyroca, is also a potential threat (N. Moores in litt. 2014, R. Hearn in litt. 2016).
CONSERVATION ACTIONS
Conservation Actions Underway
CMS Appendix I. A Single Species Action Plan was adopted by the East Asian – Australasian Flyway Partnership (EAAFP) in 2015, and a Task Force under EAAFP has been established to oversee its implementation. Baer’s Pochard is legally protected in Bangladesh, India, Myanmar, Thailand, South Korea, Russia, Mongolia and Hong Kong (China) and in some provinces in China. Some of its breeding and wintering sites are within protected areas, including Daursky, Khanka lake and Bolon lake (Russia), Sanjiang and Xianghai (China), Mai Po (Hong Kong), Koshi Barrage (Nepal), and Thale Noi (Thailand). Pochards are generally easy to maintain and breed in captivity, and approximately 150 Baer’s Pochard are held within European zoo collections, with a similar number in North America (R. Hearn in litt. 2016). Stud books are being maintained with AZA and EAZA stud book keepers appointed (R. Hearn in litt. 2016). Genetic testing of most captive birds in the UK is underway to determine their suitability for a captive breeding programme (R. Hearn in litt. 2016). A number of surveys/searches for the species have been carried out since 2012 (Hearn et al. 2013, Hearn 2015a), mainly in Russia, China and Myanmar; these have identified a number of new breeding and wintering locations (R. Hearn in litt. 2016). Since 2013 some local awareness raising has taken place in Russia, China and Myanmar (R. Hearn in litt. 2016).
Conservation Actions Proposed
Hearn (2015b) outlines key conservation actions for this species. Research its population, distribution, ecology and threats in order to understand drivers of decline produce evidence-based conservation recommendations. This may include conducting further surveys during the breeding season, particularly in China but also southern Russia including the area around Muraviovka Park on the Zeya-Bureya Plain, Far East Russia (Heim et al. 2013, R. Hearn in litt. 2016). Assess the scale and causes of habitat loss and degradation in core parts of its range (R. Hearn in litt. 2016).
Extend the area of the Khanka Lake Reserve (Russia). Protect birds at all known breeding and wintering sites, and conduct direct interventions to maximise breeding success (e.g. include provision of supplementary food and nest protection [Hearn et al. 2013]). Designate the Xianghai Nature Reserve (China) as a restricted area during the breeding season, and designate and protect Hengshui Hu, Hebei Province (China). Protect, manage and restore large wetlands in China and in other countries where the species winters (Hearn et al. 2013). Implement a global strategy for the management of captive breeding populations (Hearn 2015b). Raise awareness of this species, especially amongst policy makers (Hearn 2015b). Enforce, and develop if necessary, regulations to prevent hunting mortality and egg collection (R. Hearn in litt. 2016). Ensure legal protection of this species in all range states. |
