43 Migration routes and conservation status of the Whooper Swan Cygnus cygnus in East Asia PEIRU AO1,2, XIN WANG1, FANJUAN MENG1.2, NYAMBAYAR BATBAYAR3, SACHIKO MORIGUCHI4, TETSUO SHIMADA5, KAZUO KOYAMA6, JINYOUNG PARK7, HWAJUNG KIM7, MING MA2.8, YANG SUN9, JIANDONG WU10, YAJIE ZHAO11, WEIHUA WANG11, LIXUN ZHANG12, XIN WANG13, TSEVEENMYADAG NATSAGDORJ3, BATMUNKH DAVAASUREN3, IDERBAT DAMBA1,2,14, EILEEN C. REES15, LEI CAO1,2,* & ANTHONY D. FOX16 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. 3Wildlife Science and Conservation Center of Mongolia, Union Building B701, Ulaanbaatar 14210, Mongolia. 4School of Veterinary Medicine, Nippon Veterinary and Life Science University, 1-7-1, Kyonancho, Musashino-shi, Tokyo 180-8602, Japan. 5The Miyagi Prefectural Izunuma-Uchinuma Environmental Foundation, 17-2 Shikimi, Wakayanagi, Kurihara-shi, Miyagi 989-5504, Japan. 6Japan Bird Research Association, 1-29-9 Sumiyoshi, Fuchu-shi, Tokyo 183-0034, Japan. 7Migratory Bird Research Center, National Institute of Biological Research, Incheon 404-708, Korea. 8Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Xinjiang Uygur Autonomous Region 675502, China. 9Rongcheng Whooper Swan National Nature Reserve Management Office, Shandong, China. 10Xinjiang Bayanbulak National Nature Reserve, Xinjiang Uygur Autonomous Region 675502, China. 11Yellow River Delta National Nature Reserve Management Committee, Shandong, China. 12School of Life Sciences, Lanzhou University, Gansu 730000, China. 13Swan Nature Reserve at the Mouth of Yuyang River, Shaanxi, China. 14Laboratory of Ornithology, Institute of Biology, Mongolian Academy of Sciences, Ulaanbaatar 13330, Mongolia. 15Wildfowl & Wetlands Trust, Slimbridge, Gloucestershire GL2 7BT, UK. 16Department of Bioscience, Aarhus University, Kalø, Grenåvej 14, DK-8410 Rønde, Denmark. *Correspondence author. E-mail: [email protected]. © Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 43–72 44 Whooper Swans in East Asia Abstract The migration routes and migratory patterns of Whooper Swans Cygnus cygnus summering in western Mongolia have not previously been described and the status of the East Asian population is currently uncertain. Here we therefore use a combination of satellite tracking data, sightings of colour-marked individuals, published literature and expert knowledge to determine their distribution and site-use more precisely. Results indicated that the swans’ summer distribution extended further than had previously been recorded, with three new wintering areas (in Xinjiang, Qinghai, Gansu and Beijing) identified for the species in China. The East Asian Whooper Swan population was estimated to number 57,690 individuals, generating a new 1% threshold of 577 birds for determining sites of international importance for the species in the region. Using count data from winters 2011/12–2018/19, we identified eight wintering sites of international importance for the species in China, six in South Korea and 14 in Japan. Annual variation in national count totals highlighted the need to improve survey effort in China. Individual swans showed considerable within-winter fidelity to their wintering sites, with limited exchange between wintering areas. Migration duration, stopover duration, the number of stopover sites and migration legs were significantly greater in spring than in autumn, whilst migration speed was slower in spring than in autumn. Assessment of the habitats frequented found seasonal variation in the proportion of time that the swans spent on arable crops, pasture, wetlands and open water. From their GPS locations, 46.9%, 25.5%, 35.3% and 0.0% of the tagged swans were in protected areas during the summer, autumn staging, winter and spring staging periods, respectively. Our results provide a basis for the conservation of Whooper Swans in East Asia and illustrate the need for improved monitoring and further research into their migration, particularly for informing the protection and management of the main stopover and wintering sites for the species in China. Key words: key sites, migration route, population size, satellite tracking. Whooper Swans Cygnus cygnus breed across 2019). The little-known East Asian Eurasia from Iceland to Far East Asia, and population was estimated to number migrate to winter across temperate Europe c. 60,000 individuals at the end of the and Central Asia to China and Japan (Brazil 20th century (Miyabayashi & Mundkur 2010). Historically, five populations have 1999; Wetlands International 2019) but been described based on their largely the population trend remained uncertain discrete wintering and breeding areas: the (Wetlands International 2019). More Icelandic, Northwest Mainland Europe, recently, counts of 6,221 Whooper Swans Black Sea/East Mediterranean, Caspian/ wintering in eastern China, 5,737 in South West Siberian and East Asian populations Korea and 29,884 in Japan during winter (Rees et al. 2019; Wetlands International 2010/11 (Cao et al. 2008; Jia et al. 2016) © Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 43–72 Whooper Swans in East Asia 45 suggested a minimum population size of of sites along migration routes is still lacking 41,842 birds. The Japanese-wintering for many waterbirds in Far East Asia (Wang population trend has been reported as stable et al. 2018a). in recent years (Ministry of the Environment Although some key sites and flyway 2019; Rees et al. 2019), following an increase population abundance had been identified during the second half of the 20th century before 2000 (Miyabayashi & Mundkur (Albertsen & Kanazawa 2002), and their 1999), our knowledge about the Whooper migration routes from Japan have been Swan in Far East Asia has remained documented by satellite telemetry (Shimada rudimentary and urgently needs updating. et al. 2014). Little is known about the The aim of this analysis was to improve numbers and trends of Whooper Swans existing knowledge of Whooper Swan wintering in China, and the breeding origins distribution, migration routes, stopovers, and migration routes of Chinese-wintering habitat use and the conservation status of Whooper Swans are poorly understood, main areas used by birds that summer in although some stopover sites used by western Mongolia, and to obtain a better Whooper Swans have been identified (Zhang understanding of the Chinese-wintering et al. 2016; Li et al. 2018; Jia et al. 2019). Whooper Swans in relation to those The establishment of effective networks monitored very well over many years in of protected areas for migratory waterbirds Japan and South Korea. To do so, we is vital for sustaining migratory bird combined results from field surveys with populations throughout their annual cycle. expert knowledge, GPS tracking and ring One way to contribute rapidly to this resightings, to generate updated population process is to compare the numbers of estimates, ascertain historical trends, identify individuals using monitored wetland sites key wintering sites, and describe the across recent years, in order to assess their migration and distribution of the species in numerical importance relative to the total China, South Korea and Japan, the main numbers of individuals in the overall flyway. wintering areas for Whooper Swans in Another means of identifying important Far East Asia. Additionally we compared sites (especially in staging areas) is to deploy migration parameters recorded for GPS- tracking devices to see where, when and tagged swans during their spring and how many birds use a staging site en route autumn migrations, to provide baseline between breeding and wintering areas. information on the swans’ migration Protection of important stopover/wintering/ phenology in this flyway. summering areas is crucial to ensure that migratory species have a sufficient network Methods of suitable, secure sites and habitats available to them throughout the year, taking into Migration and ring re-sighting data consideration the effects of rapid land use Thirteen adult flightless Whooper Swans and climate change on sites along their were caught on lakes at their summering flyways. Yet knowledge about the birds’ use grounds in Mongolia. During the moulting © Wildfowl & Wetlands Trust Wildfowl (2020) Special Issue 6: 43–72 46 Whooper Swans in East Asia period, researchers used boats to catch (i.e. synthesised migrations), were extracted flightless swans on lakes by hand or with from published sources (Newman et al. hand-nets, or used boats to drive the swans 2009; Shimada et al. 2014; Supporting to the shore and into funnels nets and Materials Table S2). corrals. Swans were weighed, measured, Re-sighting data from Whooper Swans sexed using DNA analysis of pulled feather marked with neck collars (caught in the same samples, and fitted with Debut45 GPS/ way) in Mongolia in July–August between GSM (Global Positioning System/Global 2010–2019 (n = 96: 88 adults, 6 juveniles, 2 System for Mobile Communications; Druid of unknown age) and from collared Whooper Tech, China) loggers mounted on neck Swan marked in Japan in November–August collars (45.5 g, constituting < 1% of total between 1970–2009 (n = 19, all of unknown body mass of the birds). These devices sex and age) were also used to identify record instantaneous time, latitude, longitude, migration range, wintering site fidelity and altitude, temperature, humidity,