How Best to Use the Results of Waterbird Monitoring and Telemetry Studies to Safeguard the Future of Far East Asian Anatidae Species

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Moving forward: how best to use the results of waterbird monitoring and telemetry studies to safeguard the future of Far East Asian Anatidae species

LEI CAO1,2,*, FANJUAN MENG1, JUNJIAN ZHANG1, XUEQIN DENG1,2, YUSUKE SAWA3 & ANTHONY D. FOX4

1State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. 2University of Chinese Academy of Sciences, Beijing 100049, China. 3Yamashina Institute for Ornithology, 115 Konoyama Abiko, Chiba 270-1145, Japan. 4Department of Bioscience, Aarhus University, Kalø, Grenåvej 14, DK-8410 Rønde, Denmark. *Correspondence author. E-mail: [email protected]

Abstract This special issue of Wildfowl has summarised our knowledge of the biogeographical populations of ten key Anatidae species in East Asia, their current and recent estimated abundance and distributions, their migration routes and movements, and sites of importance to these populations at key stages of their annual cycles. The analysis was possible only through the active cooperation of the many biologists and site managers involved in studies of these species in different countries participating in a collaborative programme of monitoring, research and analysis. Development of new telemetry and bio-logging technology has played a key role in our ability to describe linkages between the breeding, moulting, staging and wintering areas used by individual waterbirds. Compilation of movement data recorded for tracked individuals of each species has provided initial information on flyway delineation and range definition, which forms the basis for future identification of biogeographical populations. Additionally, the tracking data have identified critical stopover and wintering sites for the different species which, when overlaid upon site protection boundaries, has enabled a preliminary appraisal of the effectiveness of current site safeguarded networks in providing adequate protection for waterbird populations along their flyways. Synthesis and analysis of new count data has permitted a description of recent population trends and a reassessment of their current size, together with recommendations for improving population monitoring into the future. High rates of utilisation of farmland habitats during staging periods within China, especially during spring migration, contrast with low levels of winter use, when most species are largely confined to natural habitats. We discuss the significance

of these facets of habitat use and the need for improved study of feeding ecology throughout the non-breeding periods, to determine optimal land management and thus inform their conservation requirements at different times of year. Finally, we consider the way forward, with a view to maintaining and building on the impressive international collaboration established to date, in order to ensure that these long distance migratory waterbirds are safeguarded for future generations.

Key words: Anser, Branta, Cygnus, distribution range, geese, Mareca falcata, migration routes, swans.

Long-distance migratory waterbirds depend Europe until the 1970s, when Atkinson- on the utilisation of a network of discrete Willes (1976) began to assess the and often widely separated wetland sites biogeographical populations of wintering along their migration corridors, to fulfil their ducks, swans and coots in order to relate needs during the course of their annual their numerical distribution to the cycle. Each site represents a link in a long assessment of the importance of individual chain of sites that provide crucial functions, wetlands to their survival in winter. This such as safety from predators, a source of process has continued, culminating with the nutrients and energy for the next step in mapping of western Palearctic waterbird their annual migration, or places suitable for distributions published in Scott & Rose social activity, such as aggregation for (1996 for Anatidae), Madsen et al. (1999 for courtship or colonial nesting. Developing geese) and Delany et al. (2009 for waders), effective conservation policies to ensure the but inevitably is an on-going process as survival of these long-distance travellers global change affects natural systems and requires both a knowledge of the our understanding develops and evolves. biogeographical population structure of Until recently, the conservation of each species, and an assessment of the Anatidae in Far East Asia has suffered relative importance of key sites to this somewhat, by comparison with Europe and population. In particular, it involves: 1) North America, because of a hitherto lack identification of groups of birds from a of information for defining biogeographical given species that consistently follow the populations, mainly due to a lack of metal same discrete migration routes (to assess ring marking of species which has been such changes in their abundance over time), and a feature of European waterbird studies 2) knowledge of the relative importance of since the 1950s (Davidson et al. 1999). Our sites for these birds along the flyway, based objective in this special issue of Wildfowl on the relative numbers using them (relative has been to summarise new data on the to the population as a whole) and their role biogeographical populations of ten Anatidae in the functioning of the annual cycle. This species in East Asia, including on their approach was initiated in the United States current and recent estimated abundance in the 1930s (Lincoln 1935) but not in and distributions, their migration routes

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 Synthesis 295 and movements and the key sites that are for the accumulation of small proportions of disproportionate importance to these of ringing recoveries, or using VHP radio populations throughout their annual cycles. techniques biased by human abilities to This has been in no small measure due to detect tagged birds, this technology has the incredible cooperation made possible enabled us within a few years to show how across the region, which has brought birds from specific breeding and wintering together the principal biologists and site areas disperse throughout the annual cycle managers studying these species in different and aggregate at important moulting, and East Asian countries, for a collaborative staging areas. The results from highly precise monitoring and research programme (see and very frequent temporal and spatial Supporting Materials Fig. S1, Table S1, location data have shown systematically how Appendices S1 & S2). In addition, the birds of different wintering provenance development of new telemetry and bio- disperse on the summering areas and how logging technology has played a key role in this results, in some cases, in completely our ability to describe very rapidly the separate migration routes and staging areas. individual linkages between breeding, Such information enables us not only to moulting, staging and wintering areas that justify monitoring these birds as separate individuals use during their annual cycle. entities and but also to identify specific sites of importance during the breeding, staging, Towards biogeographical population moulting and wintering periods. delineation So, for example, tracking results from One of our major objectives has been to Greater White-fronted Geese Anser albifrons bring together evidence to support the showed that the birds which wintered in identification of meaningful biogeographical China seemed to form a distinct entity populations in Far East Asia for the ten (defined by its members that were tracked) species considered here (although movement from those that wintered in Japan and data remain scarce particularly for the Mute Korea, not merely in being separated on Swan Cygnus olor, and regrettably we still lack the winter quarters but seldom mixing at much basic knowledge about the enigmatic other stages in their annual cycle (Deng East Asian Brent Goose Branta bernicla et al. 2020). This gives us some biological nigricans population), in a way that can justification to continue to monitor their support our ability to monitor the annual annual abundance separately in these three changes in their abundance (see Table 1). groups, as it has been politically expedient to The deployment of devices that can track do in the past, given that each country has the positions of individual waterbirds in its own waterbird monitoring programme. time and space throughout the year has been In addition, the generally low level of central to our ability to trace their precise connectivity between these groups of migration corridors and link specific places Greater White-fronted Geese gives us the used by different species at key points in basis for considering these groups as their annual cycle. Rather than wait decades discrete biogeographical populations, under

Flyway 57,690 65,000 40,000 54,000 420 Unknown Unknown

Trends Increase Increase Increase Increase Decrease Decrease Decrease Decrease Decrease estimate Unknown Unknown population

This overview includes the IUCN Winter 24,405 27,307 65,000 40,000 54,000 5,978 400 368 10 47 estimate Unknown population

Wildfowl.

Winter distribution China North/South Korea China South Korea Japan China South Korea Japan China River Yangtze Minjiang Estuary China South Korea

Flyway distribution Mongolian & N China– Flyway China E Peninsula NE China–Korean Flyway East Asian Flyway East Asian Continental Flyway Flyway Pacific West Inland Flyway Coastal Flyway

105,000 57,690 54,420 1,000 estimate East Asia population

. Provisional recommendation for the establishment of. Provisional populations of 16 flyway East Asia Anatidae species (in 27 ten Far

Table 1 Table winter management units) based on the species accounts published in this Special Issue of current estimates of List category definitions, the flyway Red species, for each winter distribution population size, flyway and their population trends. (“management wintering in each units”), the numbers Species (IUCN status) (LC) Mute Swan (LC) Mute Swan (LC) Whooper Swan (LC) Swan Bewick’s (LC) Swan Bewick’s Goose (VU) Swan Goose (VU) Swan

310,500 327,500 31,800 30,000 48,000 83,000 9,400 6,800 8,700

Stable Stable Increase Increase Increase Increase Increase Increase Increase Increase Increase Increase Decrease Decrease Decrease Unknown

229,000 123,500 204,000 80,600 24,100 30,000 48,000 83,000 7,700 9,400 6,600 2,500 900 200 Unknown Unknown

E China South Korea Japan E China South Korea Japan China China South Korea Japan China Japan China North/South Korea Japan C & E Asia

serrirostris East Asian Flyway middendorffii East Asian Continental Flyway middendorffii Flyway Pacific West Mongolia–China Flyway East Asian Continental Flyway Flyway Pacific West Flyway Eastern Palearctic East Asian Flyway Flyway Eastern Palearctic

351,700 375,500 30,000 83,000 6,800 8,700

Bean Goose (LC) Bean Goose (LC) Bean Goose (LC) Greylag Goose (LC) Greater White-fronted (LC) Goose Greater White-fronted (LC) Goose Lesser White-fronted (LC) Goose Brent Goose (LC) (NT) Duck Falcated

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 298 Synthesis the criteria recommended under the African similarly seemed to be distinct entities, but Eurasian Waterbird Agreement (AEWA our sample sizes of tracked individuals were 2005) and as previously recognised by rather small for a population with a very Wetlands International (2020) in their widespread breeding range. Furthermore, Waterbird Population Estimates 5. The telemetry a historical recovery of a Whooper Swan evidence for distinguishing breeding and ringed in Japan recovered in the Yamalo- staging areas for Japanese- and Korean- Nenets Autonomous Okrug suggests that wintering birds was far less conclusive. there is far more mixing of East Asian However, given the high winter site loyalty Whooper Swans than our results may of this species globally (e.g. Wilson et al. suggest (Ao et al. 2020a). In this case, we 1991; Warren et al. 1992; Robertson & feel justified in applying prudence and Cooke 1999), we support the continued considering this population as a single entity recognition of these three units. This means until such time that we can gather more data that each population has its own population to amend this finding. estimate based on wintering abundance, The gathering evidence for the Swan with its associated 1% criterion, used under Goose Anser cygnoides, endemic to East Asia, Criterion 6 of the Ramsar Convention as shows the existence of at least two flyways the basis for recognising a wetland of for the species. The first is an Inland Flyway, international importance to instigate site which links continental breeding areas protection (Ramsar Secretariat 2014). extending across Mongolia, Inner Mongolia, Tracking showed a similar pattern for and the Songnen Plain to Xilin Gol and Bewick’s Swan Cygnus columbianus bewickii, Kangba Noel (China) and Khanka Lake with location data from Japanese- and (Russia) with Chinese wintering areas in the Chinese-wintering birds tagged to date Yangtze River floodplain (Damba et al. demonstrating that birds from these two 2020). The other Coastal Flyway consists groups did not mix along their migration of birds summering in northern parts of corridors, nor on the breeding grounds Sakhalin and at Udyl Lake which are thought (Fang et al. 2020). However, this and other to migrate via South Korea (where some studies confirmed the remarkable dichotomy small numbers occur) to overwinter there in breeding range of Chinese-wintering and on the Minjiang Estuary, Fujian birds, with Bewick’s Swans breeding in a Province (China). However, this species westerly cluster as far west as the Yamal breeds across 30 degrees of longitude in Peninsula, where the complicating factor Mongolia alone, and the results of telemetry is that they mix with breeding birds of tracking shows the species migrating on a European and southwest Asian wintering relatively dispersed broad front (Damba provenance (Vangeluwe et al. 2018; Rozenfeld et al. 2020). This contrasts, for instance, with et al. 2019). the relatively narrow corridors taken by The results from tracking of Whooper Bewick’s Swans and Greater White-fronted Swans Cygnus cygnus showed that the birds Geese to their arctic breeding areas (Fang that wintered in Japan, Korea and China et al. 2020; Deng et al. 2020). For this reason,

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 Synthesis 299 we might expect that staging areas for birds 2020) and, from the little we know about the breeding in the extreme east and extreme species, it seems prudent to consider at least west of the breeding areas are unlikely to three potential flyway units. Telemetry data overlap along their respective migration confirmed that Mute Swans wintering along routes, which could potentially lead to the coast of eastern China coasts summered segregation and non-random pairing in this along the Selenga River (Russia), central population (see Zhu et al. 2020). However, Mongolia and in Inner Mongolia (China). for the time being and until we have the Mute Swans wintering in South Korea benefit of more genetic analysis and further apparently originate from summering areas results of telemetry studies, it seems in Inner Mongolia and the Amur Region prudent to base decisions on population (straddling Russia and China). Finally, the delineations on the major dichotomy. sedentary introduced Mute Swan population For the remaining species featured in in Japan appears to be isolated from those this Special Issue, the tracking data are elsewhere. However, there is evidently much insufficiently substantive to enable us to overlap on the summering areas for the two define flyway structures that represent major migratory Mute Swan groups, so this is a changes from the prevailing definitions of species for which we require far more biogeographical populations (e.g. those information about its summer and wintering defined by Wetlands International 2020). distributions and the relationships between We still know very little about the flyway them. structure of the Falcated Duck Mareca The East Asian Brent Goose population falcata, which is endemic to East Asia, remains one of the world’s least known but telemetry results suggest no major populations of Brent Geese Branta bernicla as differentiation to justify continuing to we still have very little information to link consider that the population constitutes specific summering and wintering areas anything other than a single entity (Zhang (Sawa et al. 2020), or even to identify all the et al. 2020). The Lesser White-fronted wintering areas used by the population Goose Anser erythropus is likely to have only (Syroechkovskiy 2006). Despite enormous one flyway (Ao et al. 2020b), especially gains in knowledge since Fox & Leafloor because the results of Lei et al. (2019) show (2018), there also remain considerable that birds caught on the wintering grounds challenges associated with identifying the at East Dongting Lake fanned out on spring flyways of the Greylag Goose Anser anser in migration towards summering areas spread East Asia. For the first time, Yan et al. (2020) across most of the known breeding range were able to clarify the relationships for the species. There remains a question between Mongolian breeding areas and mark, however, about the summering origins wintering sites in China. The telemetry data of the small but regular and increasing seem to imply two discrete corridors wintering population in Japan. The Mute connecting the eastern Mongolian/Daurian Swan remains widespread and relatively Russian and Inner Mongolian (China) scarce and scattered in East Asia (Meng et al. breeding areas with the Yangtze River

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 300 Synthesis floodplain and the Yellow River in winter. behavioural and energetic impacts of However, this dichotomy may simply result attaching tracking devices to birds against from the distribution of catch effort when the benefits to gaining further knowledge, tagging geese, as this distribution broadly there is no doubt that all the species subject reflects eastern and western extremes of the to treatment here would benefit greatly from Swan Goose (Damba et al. 2020). Finally, our further telemetry studies to extend our knowledge of Eastern Tundra Bean Goose knowledge. In particular, we remain ignorant Anser fabalis serrirostris linkages between the of the migration corridors of Eastern Taiga breeding areas in Russia and the Chinese- Bean Geese and especially the geographical and Korean-wintering areas has received a relationships between Korean- and Chinese- major boost from the telemetry studies (Li et wintering birds (particularly those wintering al. 2020). However, we still lack similar data away from East Dongting Lake) and their from birds wintering in Japan, needed to respective breeding ranges. For the Greylag provide a full understanding of how geese Goose as well, tracking birds marked away disperse from this wintering area along from breeding areas in Mongolia and at the flyway and on the breeding grounds. Chinese wintering areas away from the Likewise, we remain lamentably ignorant Yangtze River floodplain would provide about the precise numbers and distribution more information on the migration routes of Eastern Taiga Bean Goose Anser fabalis followed by the species. Mute Swan, Lesser middendorffii, both at its breeding and White-fronted Goose and Falcated Duck wintering sites. Hence, it remains difficult to would also benefit from a greater sample determine discrete flyways definitively, size of data from tagged individuals, better beyond being able to separate the Japanese- distributed from across their natural ranges, wintering birds that originate from to provide much needed insight into the Kamchatka from those wintering in China, annual movements of birds away from sites which originate from the Russian taiga zone where the small numbers have already been further to the west (Li et al. 2020). marked. Despite leaving many more unresolved questions, there is no doubt that the results Range definition of the telemetry studies have advanced our While it is naïve to expect that we could ever understanding of the connectivity between realistically define the precise edges of the the breeding and wintering areas for nine of vast areas of terrain that constitute the the species. For the tenth, the Brent Geese summer areas of many Anatidae species, of the region, we await further deployment we have taken the opportunity to use the of telemetry devices to enlighten us to the telemetry data and the engagement of precise flyways of this species which is species experts from along the flyways to poorly known in East Asia. While there is redraw the mapped boundaries of the a limit to how much more we can learn summer and wintering distributions of from bio-logging technologies and we each of the species featured here. Almost must always carefully weigh the potential without exception, this has resulted in some

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 Synthesis 301 contractions in breeding range because of extraordinary importance of particularly the new knowledge, but especially in reductions Yangtze River floodplain, which draws in the extent of wintering areas. This does waterbirds from half of the arctic tundra, taiga not automatically mean that all or indeed and steppe biomes of Eurasia during winter. any of the species have physically contracted This massive concentration of waterbird their ranges, since many distribution maps biomass from throughout the biomes of a featured in avian publications seek to vast continent underlines how critical these generalise the distribution for a range of Chinese river systems were and continue to reasons, not least because these may change be for wintering Anatidae and how we must between years and because the actual work to understand their wetland ecosystem fine-grained distribution may be poorly structure and function to best fulfil the known or patchy rather than continuous as needs of the birds that are dependent upon expediently depicted. On the summering them. Most species have shown some areas, several arctic-nesting species were signs of contraction of range within the previously shown as having ranges distributed Yangtze River floodplain in the last 10–15 well south of the coastal region, which our years, while the same is not true for the telemetry studies suggest do not in reality same species of favourable conservation constitute such importance to the birds status wintering in Japan and Korea. This during the breeding and moulting seasons pattern of range contraction within the as previously implied. It may well be that most important part of the winter quarters the birds do use these areas, but given the is especially troubling because it is also adherence of the majority of the tagged occurring on provincial and national nature birds to arctic coastal Russia, we feel it better reserves, which generally enjoy excellent to highlight the restricted nature of their protection under China’s nature conservation distribution until such time as more laws. The problems are often associated information to the contrary is forthcoming, with factors affecting the quality of the in order to draw attention of these areas nature reserves operating outside of their known to be important for different species. boundaries (e.g. concerning water quality and Based on the combination of telemetry quantity issues imposed upstream of the results, expert opinion and the results of reserve). The suspected causes of many of waterbird counts from China, we are more these declines are many, varied and most confident now that especially the winter likely interacting, and are mostly described distribution within China of most of these in detail in the species accounts of this species is highly restricted to the Yangtze special issue and elsewhere. However, and Yellow River floodplains and to the factors affecting the extent and quality of coastal fringe. As a result, the actual winter the available wetland habitats for wintering distribution within China is far more waterfowl include: physical habitat loss restrictive than suggested by the solid, rather (e.g. Jia et al. 2018), enhanced water table broad-brush patterns shown in previous drawdown (e.g. Zou et al. 2017), excessive distribution maps, underlining the truly flooding (Aharon-Rotman et al. 2017),

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 302 Synthesis extreme vegetation change (e.g. Jia et al. distance migratory species of East Asian 2017), human disturbance (e.g. Zhang et al. waterbirds that breed in the arctic use 2019), loss of submerged macrophytes (Fox seven discrete migratory corridors and et al. 2011) and isolation (through dam therefore seem to constitute separate construction) from the hydrology of the biogeographical populations. These are floodplain (e.g. Xia et al. 2017). The scale and two populations of Bewick’s Swan, two extent of the problems underline the need of Eastern Tundra Bean Goose, two of for catchment management scale solutions, Greater White-fronted Goose and a single as well as tackling issues at the local, basin Lesser White-fronted Goose population. level to restore biodiversity and wetland Their breeding distributions range from the function, both of which require integrated Yamal Peninsula in the west to Chukotka in research to establish the ultimate causes and the east. All of these species have their identify solutions (Cao & Fox 2009). main wintering sites in the Yangtze River floodplain and the middle and lower reaches Critical stopover sites of the Yellow River in China, in South Although not a major output of these Korea and along the east and west coasts of species accounts, the use of telemetry Japan. Six of these migratory populations has highlighted the importance of critical (excepting the Eastern Tundra Bean Goose stopover sites used by a suite of species in on its West Pacific Flyway) mainly stage in their annual migrations between winter northeast China, in areas which include quarters and breeding areas. Although such the Songnen and Sanjiang Plains. This areas may be used for relatively restricted congruence of staging areas highlights the periods of the annual cycle (a few weeks importance of this part of northeast China compared to several months spent on the as a vital source of energy and nutrients for winter quarters), their intensive use as a these birds, especially as they head north in source of energy, nutrients and minerals at spring. Future analysis will also provide more crucial points in the annual cycle make them detailed information across the different of disproportional importance for staging species on the habitat types, safe roosting waterbirds. Further assessment of the areas and precise core foraging areas used by cumulative use of staging areas, by multiple these birds, the degree to which these are numbers of individuals of the same and situated within currently protected sites and different species, would highlight the great the precise duration of their staging importance and value of these sites for a phenology, which will provide the spatial range of waterbirds in their annual cycle. We and temporal basis for providing more propose to undertake a more detailed, effective protection in these critical areas. sophisticated and in-depth analysis of these Six species within East Asia undertake data in the near future. relatively short migrations between the However, in the meantime, the results breeding and wintering grounds and, on the that have come through from the data we basis of work presented here, it appears that present here shows that the four long- these comprise nine discrete migratory

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 Synthesis 303 biogeographical populations (two of Mute recent years (Xu et al. 2019). We therefore Swans, one of Whooper Swans, two of need to continue the work of identifying the Swan Geese, at least one of Greylag Geese, most important features of these areas, and two Eastern Taiga Bean Geese populations to protect and improve the few remaining and a single Falcated Duck population). wetlands as best we can, so that these birds These species breed across the Mongolian can continue to migrate successfully between steppe, in northeastern China and to their breeding and wintering areas as they do different degrees throughout the Russian now. However, just as important is to attempt taiga zone, as well as the Ulbansky Bay to restore yet more degraded wetlands, in region and northern Sakhalin Peninsula. order to buffer against the potential further They winter mainly in the Yangtze River loss of existing sites as a result of climate floodplain, the middle and lower reaches of and other environmental change. the Yellow River and on the Minjiang River It is striking, on comparing results across estuary in China (in the case of the Swan the different species, how many tagged Goose), Bohai Bay in the Yellow Sea in waterbirds used areas of cultivated land and China, in South Korea and on the east and agricultural grassland on the spring and west coasts of Japan. These populations autumn staging areas (e.g. Lesser White- mainly staged in China and North Korea, fronted Geese; Ao et al. 2020b). This is made including on the Inner Mongolia wetlands all the more interesting by many of the same (Bayannaoer and the Hetao Plain), along species assiduously avoiding using such coastal areas of the Yellow Sea (Bohai Bay farmland in winter, despite the apparent and Yalu River estuary), the Hei River in abundance of suitable available farmland, Gansu Province, and (as in the case of the and its profitability as a food resource for longer distance migrants) in the Songnen the birds on the winter quarters in China and Sanjiang Plains in northeast China. (e.g. Yu et al. 2017; Zhao et al. 2018). Given Among these, it is important to stress that the importance of crops as energetic and the staging sites in Inner Mongolia and nutritional resources for migrating geese Heihe in Gansu are situated in extremely along the spring migration corridor and arid areas, where the wetlands are usually their potential effects on reproductive small and the extent of open water area output, we would stress the importance of varies greatly within and between years. ecological studies on these spring staging These factors mean that there is a more waterbirds for elucidating how we might urgent need to maintain these crucial but enhance their ability to acquire nutrient often ephemeral elements of the wetland and energy stores at stopover sites. We network (which are so sensitive to climate should be wary of encouraging Far East change), to support the birds through Asian staging waterbirds to abandon natural different seasons and in different years. wetlands in favour of sustaining higher rates In addition, coastal wetlands as well as of nutrient acquisition and energy stores wetlands further inland in northeast China from agricultural subsidies on farmland have been lost and severely degraded in habitats (as this can lead to agricultural

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 304 Synthesis damage issues, as in Europe and North Asian flyways. Most conspicuously, all the America; see Fox & Madsen 2017). declining populations are those that winter Nevertheless, it is undoubtedly worth in China, with the exception of the tiny exploring the potential to plan for numbers of Bewick’s Swans and Swan sympathetic management of farmland to Geese that winter in South Korea. We provide food for spring staging geese and should be particularly concerned about perhaps even sacrificial crops to support declines in Bewick’s Swans and Swan Geese them during the short spring staging period (both those in the Inland and Coastal in focal areas (as suggested for the winter flyways) because until recently Chinese- quarters; Si et al. 2020). We would encourage wintering Bewick’s Swans were thought to a burgeoning of field studies of spring- be of favourable conservation status. Both staging waterbirds in key areas identified by species are specialists that feed by grubbing these studies, not just to establish the key the highly nutritional below ground storage overnight roosting sites and associated organs of aquatic plants, sequentially exposed feeding areas, but to establish their diet, by water table recession in the Yangtze River preferred versus available foods, and the floodplain wetlands (as elsewhere), sensitive levels of stress from local disturbance to water level change. Too rapid water table events. Such studies would support the drawdown and the substrate dries out, development of site protection networks becoming impenetrable, making abundant and enhancement of feeding opportunities rhizomes inaccessible, but too much for the species, in concert with public flooding and neither species can reach into outreach programmes to engage local the shallow flooded substrates to extract communities in the enjoyment and their food items from the otherwise soft protection of this valuable resource for substrate. There is also evidence of engaging people with wildlife. widespread loss of their food plants due to large-scale environmental change (e.g. Fox Status and distribution et al. 2011; Jia et al. 2017), which may be to The special issue has summarised the status the advantage of more generalist species of 27 “flyway management units” for the ten such as Eastern Tundra Bean Geese which waterbird species featured here (Table 1). Of can apparently more easily switch between these, we now have a good idea of the alternative food sources, including several population size of 24; only for Mute Swan food items such as Water Chestnut Trapa are robust abundance assessments missing natans fruits, apparently not exploited by for both management units in Far East Asia other sympatric wintering waterbird species and with trends unknown for one of the (e.g. Zhao et al. 2010). Of continued concern Brent Geese groups. Of the remainder, are the declines among Greater White- 14 are increasing, two considered stable fronted Geese wintering in China (Deng and eight are considered to be in decline et al. 2020), for which loss of recessional (Table 1). This overview gives a sound basis sedge meadows have been identified as the for establishing priorities within the East cause of the loss of the species at sites such

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 Synthesis 305 as East Dongting Lake. Elsewhere, the gain feeding conditions in autumn continuing of such sedge beds has resulted in the into spring (Wang et al. 2013). appearance of the species at sites such What these trends identify is the urgent as at Shengjin Lake (Zhao et al. 2012), need to maintain and improve the current experiences which suggest that sensitive mechanisms put in place to monitor hydrological management to maintain and effectively the numbers of birds in these manage such graminoid stands could benefit flyway groupings, which we are tentatively the species at a number of sites (e.g. Guan identifying as biogeographical populations. et al. 2014, 2016). The status of the Lesser Building on the advances made in recent White-fronted Goose gives greatest concern years, it is important to clarify further the of all, because of its precipitous decline in flyway relationships within species, for the last ten years (Ao et al. 2020b). Again, understanding how best to treat their current changes in hydrological management of and future management. Outside of this sections of the East Dongting Lake process, it remains essential to maintain National Nature Reserve have resulted in the excellent mid-winter waterbird count losses of monotypic graminoid swards, programmes established in Japan and South upon which this specialist short sward Korea, and to extend these to some species grazer seemed to specialise in feeding in such as the Mute Swan that may require autumn and spring (Cong et al. 2012; Wang other approaches for their effective annual et al. 2012, 2013). The same authors showed population assessment. We have seen the that in mid-winter, when such swards enormous strides made in China since the were denied them, the species was unable 1990s, where waterbird monitoring has gone to maintain energy balance on more from being largely restricted to nature extensively available sedge meadows and reserves to the extensive annual coverage of lost body mass, underlining the birds’ all wetlands in the Yangtze River floodplain reliance on habitats that have now been that we see today. This effort must be lost from the site which once regularly maintained and enhanced but also extended supported several thousand individuals (Ao to other major river systems and coastal et al. 2020b). Perhaps more seriously, in one areas, which offer potential waterbird year when high water levels prevented the wintering habitat elsewhere in China. This is Lesser White-fronted Geese from using especially the case for the Huai and Yellow these favoured recessional grassland feeding Rivers where, despite the massive loss of areas in late autumn, their fat stores wetlands in relatively recent times and the remained lower throughout the entire fact that they are mostly frozen in mid-winter, winter. The following spring, geese left for there are prospects for extensive waterbird their breeding areas in poorer condition and habitats in the future, given climate change later in spring than in the previous year, and the opportunity for widespread habitat perhaps reflecting consequences of the need restoration and remediation. to gain threshold fat stores for migration, but We should also be mindful of the need potentially hinting at carry-over effects from for demographic monitoring in parallel

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 306 Synthesis with mechanisms for estimating population autecological studies provided some insight size and trends, in order to understand into the potential causes of declines the drivers behind changes in waterbird resulting from habitat loss or modification population abundance. Extensive annual age on the wintering grounds (see above). ratio determinations have been instigated on The loss of an extensive area of a single the wintering grounds in China, which enable species graminoid community demonstrably assessments of year-specific recruitment of affected the fat store acquisition in this young to wintering populations. Although species compared to a previous year (when only currently available for a modest number such habitat was available) in a quasi- of years, continuing and expanding such experiment which was also associated with assessments (e.g. to Korea and Japan) will reduced fat stored and delayed spring build a vital time series of measures that departure (Wang et al. 2013). Permanent loss should establish the degree of between-year of such habitat apparently resulted in variation in reproductive success which disappearance of the species from the site can then be incorporated into population and declines in the Lesser White-fronted modelling, even in the absence of other Goose flyway population as a whole (Ao informative population parameters, such as et al. 2020b). This is a clear warning about using capture-mark-recapture techniques to how loss of a relative modest area of specific estimate annual survival rates (e.g. Johnson habitat within a National Nature Reserve et al. 2018). due to changes in aquaculture can affect rare species of high conservation status, and the Habitat use vital importance of sympathetic management As evident from the Lesser White-fronted at such sites for species of unfavourable Goose example above, access to specific conservation status. food resources that can meet the seasonal Lesser White-fronted Geese are arguably energetic, nutritional and mineral needs at among the more specialised of feeders of key points throughout the annual cycle is the waterbird guild examined in the potentially critical for optimal survival and accounts of this special issue, so they are reproduction. Not surprisingly, across all perhaps among the most likely to suffer species, results from tracking presented from specific habitat loss compared to here show that, during the breeding season, more robust species that show greater most of the studied waterbirds exploit ability to switch between food supplies. natural habitats in tundra and taiga biomes Nevertheless, for all the species featured that are generally less affected by human here, their effective conservation requires activities (with the exception of local impacts an understanding of their habitat use and in the vicinity of settlements and the wider ideally a framework for the effective effects of climate change) than is the case in protection of their habitat in a condition to the staging and wintering areas further maintain current population levels and, in south. The case of the Lesser White-fronted the case of populations showing declines, Goose is one of the few in the region where some mechanism for reinstating lost habitat

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 Synthesis 307 or providing new food sources. One of the of the studies presented here, we have early findings from tracking habitat use by support for the hypothesis that the declines five goose species at Poyang Lake was to in Chinese-wintering birds are unlikely to show that they rarely fed outside of the be responsible for the increases in Korea wetlands on farmland areas (Yu et al. 2017) and Japan over similar time scales because and that the way these goose species geese using these flyways seem largely exploited the various natural habitats that discrete. This represents further support for provided them with food was intimately the hypothesis that Japanese- and Korean- related to patterns of water table drawdown wintering goose numbers are increasing as that affected plant growth and community a result of exploitation of new, formerly composition patterns, as well as accessibility unoccupied habitats in the form of to that food supply in time and space surpluses of food available to them on (Aharon-Rotman et al. 2017). The same agricultural land, whilst Chinese-wintering seems true to some extent for duck species birds are limited in a density dependent as well (Meng et al. 2019), whereas cranes fashion by the extent and quality of declining (for example the Hooded Crane Grus natural habitats there. This presumably monacha at Shengjin Lake, Anhui Province) contributes to the explanation why this is have shown an increasing tendency to feed the case compared to elsewhere in the away from wetlands on farmland, especially Northern Hemisphere, where the same on paddy fields (Zhou et al. 2009; Fox et al. species of geese are generally increasing 2011), where they are highly disturbed by after the transition to feeding on farmland in human activities there (e.g. Li et al. 2015). winter (Fox & Madsen 2017). The energetic costs of susceptibility to high Further evidence that human persecution levels of human disturbance, as well as the and disturbance keeps these large-bodied very real risk of mortality from human waterbirds from foraging on farmland close agency, has been suggested as the reason to wetlands on their Chinese-wintering why particularly the goose species which use quarters comes from the fact that the farmland in Korea (e.g. Lee et al. 2006; Kim tracking data presented here conspicuously et al. 2016) and Japan (e.g. Amano 2009; confirm that several of the same species Fujioka et al. 2010) do not do so in the are largely restricted to wetlands in winter, Yangtze River floodplain (Yu et al. 2017; whereas they somewhat surprisingly stage Zhao et al. 2018). As a result, the wintering on agricultural habitats in China during habitat of Chinese-wintering geese has been spring and autumn. So, for instance, data interpreted as being limited by the extent from the tracked Whooper Swans showed of traditionally used wetland habitat and that > 80% of the positions were recorded their generally declining population trends from open water or wetlands combined in interpreted as a sign of reductions in the winter, but > 70% came from grassland or extent and quality of those wetlands upon crops during spring en route to ultimate which they are dependent (e.g. Jia et al. 2018). breeding areas (Ao et al. 2020a). Even As we have seen from the results of several among tagged Lesser White-fronted Geese,

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 308 Synthesis which were almost entirely confined to management; Aharon-Rotman et al. 2017), wetlands in Poyang Lake (Yu et al. 2017) and reducing disturbance to allow access to overall > 80% were on wetlands in winter natural habitat, but potentially also to (Ao et al. 2020b), 52% of spring staging farmland food resources (Si et al. 2020) or positions came from farmland (Ao et al. indeed, in the extreme, providing artificial 2020b). This supports similar evidence from feeding, as in the case for Lesser White- another tracking study which showed that fronted Geese in Japan (Ao et al. 2020b) and Greater White-fronted and Eastern Tundra Whooper Swans in Shandong and Henan Bean Geese intensively used farmland at Provinces, China (Ao et al. 2020a). their Chinese stopover sites, but hardly at all at their wintering site, even though farmland Conservation was available in similar proportions in So for these species, the material presented both regions (Si et al. 2020). These authors here provides an improved overview of the inferred that human pressure on both flyway structures of these waterbird farmland and wetland/grass was significantly populations in Far East Asia which enables lower at the stopover region compared to the responsible authorities (both supra- the wintering region and in both regions, the national NGOs such as The East Asian- two goose species selected for farmland Australasian Flyway Partnership and Wetlands and/or wetlands/grasslands with relatively International, as well as statutory national low human pressure close to roosting sites. agencies) to make more informed decisions Clearly site protection is not enough to about which biogeographical groupings safeguard long-distance migratory waterbirds of birds constitute logical population at all stages of their life cycle. The message management units, for the purposes of coming from the results of using tracking monitoring and management (as is the case data to map habitat use is that such data need elsewhere, see for instance Marjakangas et al. to be combined with field-based studies to 2015). On the basis of the preliminary reveal habitat selection and the processes findings regarding flyway structure, it has driving these patterns. Habitat use is shaped been possible to see that the goose species not just by the attractiveness of the food wintering in Japan and Korea generally have supply at a given point but also by the range more favourable conservation status than of choices available within a given radius those wintering in China, which immediately and the other factors affecting the relative provides the basis for the most effective attractiveness of these choices (such as deployment of scarce conservation resources. human disturbance, predation risk, food In China too, it is evident that for many availability and depletion). Such studies need species the winter range has contracted and, to be undertaken interactively on site in in particular, habitat loss along the coast has order to understand how to deliver effective resulted in the concentration of wintering conservation on the ground, for instance swans and geese increasingly in the Yangtze with regard to managing the food resource River floodplain where, until very recent to best effect (e.g. through water level years, the annual cycle of summer monsoonal

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 Synthesis 309 inundation followed by winter water table 2016; Jing et al. 2017; Zou et al. 2017, 2019). recession offered vast areas of suitable The net results of such losses throughout wintering habitat. However, even here, the the Yangtze River floodplain is to concentrate combination of aquaculture, pollution, more and more waterbirds at the vast habitat loss and degradation has also Poyang Lake which remains the “jewel in the concentrated wintering waterbirds into crown” of Yangtze waterbird reserves, the the fewer and fewer basins less degraded most important and well protected of all the by development, urban and agricultural Yangtze wetlands. Yet this site too, one of pressures (Fang et al. 2005, 2006). In very the few Yangtze River floodplain wetlands recent years, for instance, individual basins not currently subject to sluice control (Xia have suffered disproportionately from et al. 2017), is being threatened by the development pressures, as was the case at construction of many dams in its own Huangda Lake, a large shallow lake in Anhui catchment and a major dam to isolate it Province which suffered major habitat loss from the main river. To combat wetland combined with heavy catchment pollution loss, the Jiangxi Provincial Government effects (including a major pollution event submitted a Poyang Lake water control that seriously affected the western part of project proposal in 2012 to retain high the lake in 2016) that contributed to very winter water levels within the lake (c. 4 m poor water quality (Hong et al. 2018) and the higher during November–March than the lowest recorded levels of water transparency average winter levels, based on those among 50 monitored Yangtze River measured at the nearby Wusong monitoring floodplain lakes (Feng et al. 2019). Poor station) to protect the lake ecosystem from water transparency inevitably impacts on further deterioration (Zhang et al. 2014). submergent plants such as Tape Grass The proposal has raised scientific concerns Vallisneria sp. (e.g. Fox et al. 2013), which because it will maintain constantly high are so vital for wintering waterbird species. water levels throughout the dry season (e.g. As a result of the encroachment of such Jiao 2009), which would have detrimental development pressures (e.g. Zhang et al. effects on the feeding opportunities of 2019; Gao et al. 2020) and hydrological many waterbird species (Aharon-Rotman isolation of lakes from the Yangtze (Xia et al. et al. 2017). As we write in November 2020, 2017), we see more species being lost from despite the scientific opposition, this threat lakes throughout Hubei and Anhui Provinces. has not gone away. Even worse, we see species being lost Equally, it is important to stress that there from East Dongting Lake (despite its vast has been great progress made in protecting area and connection to the Yangtze), not and restoring lost habitats in some lakes. only because of changes in aquaculture At Shengtian Lake (Shanxi Province) (described above), but also through sympathetic management has been instigated hydrological changes resulting from water and waterbirds have returned, while at management associated with the Three Longgan Lake (Anhui Province) ecological Gorges Dam (Zhao et al. 2012; Zhang et al. restoration of wetland areas that had

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 310 Synthesis formerly been used for farmland, as well as which are actually already protected, the banning of fishing net areas has seen the amongst other things, for their importance recovery of many species, including Greylag for wintering waterbirds, which as we Geese (Yan et al. 2020). At this site, have seen, are of continental and global restoration of formerly cultivated land to significance. Ideally, restoration and the shallow water areas have created extensive implementation of sympathetic management beds of Wild Rice Zizania latifolia, which will involve research and monitoring to large numbers of Greylag and Eastern provide an adaptive management framework Tundra Bean Geese have begun to exploit in to understand how best to implement winter. However, there are indications that actions for restoring wetland functions and these geese are also increasingly feeding out enhancing waterbird populations, but also to on adjacent farmland, potentially further continue improving knowledge of species extending the more natural carrying capacity ecology and their interaction with their of the system (Yan et al. 2020). At Chen environment. Nature is a great healer and Lake (Hubei Province), local improvements the dynamism of the seasonally ephemeral to wetland management have greatly Yangtze River floodplain wetlands makes it improved local conditions for wintering easier to start each flooding season afresh, waterbirds, and removal of seine nets from with the potential for renewal in time for 70% of the lake area has also made a major each following wintering waterbird season. contribution (Yang et al. 2017). Removal of Such restoration can also contribute to all fishing nets, cages and dams at Huanggai economic improvements and ecosystem Lake (Hunan Province) had similar effects, service provision to human livelihoods in and at Wuchang Lake (Anhui Province) the the region, such a flood alleviation (Cao et al. reconstruction of lost waterbird habitats 2018). and wetland restoration has also been A major potential management issue is implemented to the benefit of wintering the thorny question of whether we should waterbird numbers (Yan et al. 2020). encourage Chinese-wintering waterbirds to To protect this vital migratory waterbird feed on agricultural subsidies (such as waste resource, the first line of attack must be to grain, maize and rice) on farmland adjacent restore all the Yangtze wetlands to their to wetlands as a way of extending the former states along similar lines to those carrying capacity of the winter grounds for undertaken as described above, no matter these birds. We would encourage that the how damaged, because as demonstrated by implementation of all possible measures to the examples presented, as long as the restore the more natural carrying capacity of physical wetland conditions remain, restored Yangtze River floodplain wetlands (and lost and degraded habitats and wetland those elsewhere in China) are initiated functions can attract the numbers and first, before resorting to such artificial diversity of waterbirds that they formerly methods. There is no doubt that while goose supported. This is especially the case for populations around the rest of the provincial and national nature reserves Northern Hemisphere have benefitted from

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 Synthesis 311 exploiting temperate farmland landscapes the “genie out of the bottle” and creating for food (in a way Chinese-wintering geese conflict from burgeoning goose populations have failed to do) they have done so at a in the future that are already evident price. The conflicts caused by the explosion elsewhere in the Northern Hemisphere in goose numbers on farmland in North (Fox et al. 2017). We do, nevertheless, America and Europe (at a time when all acknowledge, that for species like the Lesser other aspects of farmland biodiversity are White-fronted Goose, that has physically generally crashing, e.g. Butler et al. 2007) are lost suitable habitat due to changed well described (see Fox & Madsen 2017 and aquaculture management at Dongting Lake references therein). The unusually intense and which seems to have taken to feeding on levels of human activity and persecution of provisioned grain in Japan (Ao et al. 2020b), waterbirds on Chinese farmland seems to this may offer a stop-gap solution. If no constitute the reason that geese cannot other means of reinstating natural habitat exploit farmland in their wintering sites and can be found, providing artificial food hence are confined to their deteriorating may be a legitimate short-term means of natural habitat. If this were to be case, contributing to ensuring the survival of this creating areas free from human disturbance small and rapidly declining population in the on farmland close to wetlands clearly offers first instance, especially if limited in time an opportunity to conserve their numbers in and space. The Lesser White-fronted Goose the face of continued habitat loss and is not alone in this instance; Hou et al. degradation. As we have seen, geese used (2020) showed loss of Tape Grass tubers farmland intensively at Chinese staging at Poyang Lake caused Siberian Cranes stopover sites, but hardly at all on their Leucogeranus leucogeranus to abandon traditional winter quarters (Si et al. 2020). All these wetland habitats to resort to farmland, findings suggest that reductions in human especially during a major loss of tubers in pressure on farmland close to wetlands 2015/16. Those authors also suggested that might enable wintering geese in the Yangtze “agricultural fields can be important refuges to benefit from feeding on energy-rich food for Siberian Cranes, mitigating the negative items left in fields on farmland post-harvest, impacts of wetland deterioration”. Artificial especially in areas already subject to low feeding of wintering cranes in Japan is long- levels of human activity. However, this would established and widespread, a practice which also increase the extent of interactions is also exploited by many other species of between domestic ducks feeding in areas migratory waterbirds there (e.g. Masatomi & close to nature reserves and wild migratory Masatomi 2018). In South Korea, the tiny waterbirds, which already creates potential group of Swan Geese which winters on for transmission of parasites and disease the Seocheon River estuary fed on the between the two (e.g. Prosser et al. 2015). For overwintering tubers of intertidal Alkali these powerful reasons, we remain hesitant Bulrush Bolboschoenus sp., which formed to recommend this as a first line of attack to the main dietary item throughout the enhance population sizes, because of letting entire winter period, but the species also

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 312 Synthesis increasingly resorted to rice paddies from specific protection of population flyways, November onwards, suggesting depletion of simply by analysing the degrees to which natural food resources and/or a change in tagged birds were using sites with some level dietary requirements that was fulfilled by the of protection. Ground surveys of staging shift to agricultural land (Choi et al. 2017). birds on spring and autumn passage should We therefore need to be mindful of the be targeted at areas which appeared opportunities as well as the hazards of especially important which are currently artificial feeding, provision of sacrificial unprotected, with a view to assessing crops and establishing disturbance-free numbers and distribution of staging birds to areas on farmland in close proximity to determine their relative importance and wetlands, as contributions to our strategies qualification for site designation, and to to protect these populations for future assess the key food items, sources of food generations, whilst not resorting to them in and habitat requirements in the vicinity (e.g. the first instance before attempting to safe-drinking and night-roosting areas) that improve natural habitats. contribute the integrity and functional While there are particular problems importance of the site should it qualify for associated with waterbirds on their wintering protection. ground within China, we should not lose sight of problems to be solved elsewhere Where next? along the flyways. In many of the Despite the many leaps forward presented population accounts presented in this in this special issue, there have been many special issue, we analysed the levels of site issues that we have not touched upon. protection among the places visited by our For instance, infrastructure development telemetry tagged birds throughout their (including wind turbines, cables, towers and annual cycle. Although it is difficult to set masts) built across waterbird flyways can hard and fast thresholds for what constitutes also be a threat, but at least now that we are acceptable levels of site protection for a more aware of the migration corridors of given population, there was little doubt these large-bodied and vulnerable species, that for all species there was room for we are better able to identify potential improvement. For Whooper Swans, for conflict areas and provide suitable advice. instance, tagged birds almost never used Over-harvesting and persecution remain spring staging areas that enjoyed any level of serious threats, particularly at key migration site protection whereas during winter (35%) locations; this requires international and summer (47%) greater proportions of coordination to identify, quantify and find sites used by tagged individuals were legal and enforcement solutions. Climate protected (Ao et al. 2020a). Clearly there is change is clearly already affecting many much to be done to undertake similar, more avian species, including those described detailed analyses for these and other species, here, but the patterns we have established in to assess how well the currently designated time and space will serve as a baseline for network of protected areas contribute to the future studies. Climate change is expected to

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 Synthesis 313 exacerbate all these pressures, and may also species’ populations, and the extent and increase competition between migratory and quality of their habitats, at other times of non-migratory species and between those the year. We have to work together and who perhaps have never before been coordinate actions if we are to be at all sympatric but which now are so because of effective. International collaboration and climate-induced range changes. Waterbird coordinated action along migration flyways conservation requires a multitude of as a whole are thus key elements in any complementary approaches to be truly strategy for the conservation of migratory successful. Such long-distance migrants birds. The flyway approach is the only way require cohesive networks of protected forward in the first instance, and we have areas, but in order for these to be successful, now embarked upon this to greater or lesser they need targeted effective management at extents for all the species described here. these sites. Important Bird Areas (IBAs) The next priority is to identify the particular provide an important foundation for such issues encountered by populations in action; however, to function effectively in unfavourable conservation status and tackle conserving migratory species, IBAs need to the problems faced by each, identifying the be protected and the coherence of the causes of declines and establishing where network requires regular review, both for we can have maximum effect through site integrity and function but also to targeted management interventions along optimise management for the birds that use the flyway. This requires coordination and them. Because so many of the species we joined-up thinking, international consultation have dealt with here are distributed across and coordination through organisations truly vast expanses of tundra, taiga and such as the East-Asian Australasian Flyway steppe biomes often at very low breeding or Partnership. The accounts presented in this summering densities, we also need to be special issue already represent a massive mindful of how to address human-induced development of collaboration between the changes at the wider landscape scale, even parties of the flyways and the long lists of if this constitutes a particularly difficult co-authors and their affiliations bear witness set of challenges. However, again, the data to the huge leaps in coordination and presented here are among the very first to cooperation achieved to date. Although establish spatially explicit migration routes the analyses have inevitably concentrated and occupancy of breeding ranges for all the upon problems faced by waterbirds on the species considered, so at least we cannot wintering grounds, especially in China, hide from the knowledge of where these there are a new set of challenges to be met challenges may occur. in the immediate future at other stages of With this point in mind, it is of course the annual cycle, which we also need to self-evident that efforts to conserve migratory tackle collaboratively. We must not fail birds at one stage of their annual cycle are those who come after us by protecting what potentially rendered totally useless if other we still have right now, but in the face of pressures or threats are reducing these ever-increasing pressures on these unique

© Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 293–319 314 Synthesis birds, it is evermore urgent that we this special issue and for working so hard to safeguard these waterfowl populations for see it through to fruition. future generations. References Acknowledgements Agreement on the Conservation of African- None of the enormous body of work in this Eurasian Migratory Waterbirds (AEWA). 2005. special issue could possibly have been Proposal for Guidance on the Definition of achieved without the incredible hard work Biogeographical Populations of Waterbirds. AEWA, and dedication of literally thousands of Bonn, Germany. Available at https://www. unep-aewa.org/sites/default/files/document/ people, who have helped us with developing mop3_12_guidance_biographical_population_ software and hardware, by catching birds in waterbird_0.pdf (last accessed 22 July 2020). the field and by attaching tracking devices Aharon-Rotman, Y., McEvoy, J., Zheng, Z., Yu, then downloading and analysing the data H., Wang, X., Si, Y., Xu, Z., Zeng, Y., Jeong, coming from them. We are hugely gratefully W., Cao, L. & Fox, A.D. 2017. Water level to an army of people devoted to waterbirds, affects availability of optimal feeding habitats many of whom are acknowledged as co- or threatened migratory waterbirds. Ecology authors of the papers, but also to the many and Evolution 7: 10440–10450. more who have helped diligently at the Amano, T. 2009. Conserving bird species in catching sites (see Supporting Materials Japanese farmland: past achievements and Fig. S1, Appendix 1) or with counting future challenges. Biological Conservation 142: birds in the field, often under the most 1913–1921. Ao, P., Wang, X., Meng, F., Batbayar, N., uncomfortable of conditions (see Supporting Moriguchi, S., Shimada, T., Koyama, K., Materials Appendix 1). Much of the Park, J.-Y., Kim, H., Ma, M., Sun, Y., Wu, J., discussions and planning for the work Zhao, Y., Wang, W., Zhang, L., Wang, X., summarised here occurred at three major Natsagdorj, T., Davaasuren, B., Damba, I., international flyway meetings that took Rees, E.C., Cao, L. & Fox, A.D. 2020a. place in China. Without the selfless and Migration routes and conservation status major contributions from the delegates to of the Whooper Swan Cygnus cygnus in East those meetings, none of this would have Asia. Wildfowl (Special Issue No. 6): 43– been possible (see Supporting Materials 72. Appendix 2). Finally, we thank the Chinese Ao, P., Wang, X., Solovyeva, D., Meng, F., Academy of Sciences, the National Natural Ikeuchi, T., Shimada, T., Park, J., Gao, D., Science Foundation of China and the Liu, G., Hu, B., Natsagdorj, T., Zheng, B., Vartanyan, S., Davaasuren, B., Zhang, J., Cao, Ministry of Science and Technology of the L. & Fox, A.D. 2020b. Rapid decline of the People’s Republic of China, who all geographically restricted and globally supported the study and all the funding we threatened Eastern Palearctic Lesser White- have received in support of this work. Last, fronted Goose Anser erythropus. Wildfowl but absolutely not least, we remain forever (Special Issue No. 6): 206–243. deeply indebted to Dr Eileen Rees for her Atkinson-Willes, G.L. 1976. The numerical enormous encouragement to us to publish distribution of ducks, swans and coots as a

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