Migration routes and differences in migration strategies of Whooper Swans between spring and autumn

Long-distance migratory birds travel more rapidly in spring than in autumn,as they face temporal breeding constraints.However,several species travel slower in spring owing to environmental influences,such as food availability and wind conditions.GPS trackers were attached to 17 Whooper Swans(Cygnus cygnus) inhabiting northeastern Mongolia,to determine their migration routes and stopover sites in spring and autumn.Differences between spring and autumn migrations,migration-influencing parameters,and the effect of spring stopover site temperatures were analyzed.Six swans completed perfect tours between their wintering and breeding sites,and these data were used for analysis.Spring migration lasted 57 days,with 49.2 days spent at 3.7 stopover sites.Autumn migration lasted 21.5 days,with 17.5 days spent at 1.0 stopover sites.Thus,the swans traveled more rapidly in autumn than in spring.Migration distance,number of stopovers,migration speed,and straightness were important migration determinants in both spring and autumn.Migration distance,stopover duration,number of stopovers,daily travel speed,travel duration,and migration speed differed significantly between spring and autumn.During spring migration,the temperature at the current stopover sites and that at the future stopover sites displayed significant variations(t=1585.8,df=631.6,p <0.001).These findings are critical for the conservation and management of Whooper Swans and their key habitats in East Asian regions,and the data are anticipated to make a particularly significant contribution toward developing detailed management plans for the conservation of their key habitats.

中国越冬白琵鹭(Platalea leucorodia)的分布与种群趋势研究

白琵鹭(Platalea leucorodia)东亚种群在中国、韩国和日本越冬,其中中国越冬群体的分布和数量研究甚少。文章基于鸟类遥测和调查数据,提出了对中国越冬群体度夏和越冬分布范围的修订建议,在国际鸟盟出版的物种分布图基础上,新增蒙古国中部和中国黄河流域河套平原为度夏地;新增江苏沿海地区为越冬地,而在浙江、福建、广东和广西的分布范围仅保留沿海区域。首次准确估计了东亚种群数量约为20000只,包括中国越冬群体数量约为19500只,韩国约300只,日本约80只。相比2012年的种群数量估计值10000只,东亚种群数量已经翻倍,这主要由于中国群体数量的增加。2016~2020年期间,占东亚总数97.5%的白琵鹭分布在中国长江流域的16个关键越冬位点,且50%以上的个体在鄱阳湖越冬。近年来,随着白琵鹭种群数量增加,其在长江的越冬分布范围更加广泛。

Assessing site-safeguard effectiveness and habitat preferences of Bar-headed Geese (Anser indicus) at their stopover sites within the Qinghai-Tibet Plateau using GPS/ GSM telemetry

Background:The Bar-headed Goose(Anser indicus)breeds across the high plains and plateau of Central Asia and winters in the Qinghai-Tibet Plateau(QTP),the Yunnan-Guizhou Plateau and the Indian sub-continent.Of the two recognized discrete flyways of the Bar-headed Goose,the Eastern Tibetan Flyway(ETF)is the larger,comprising at least six migration routes.However,we remain ignorant about their migratory connectivity,habitat use and effectiveness of site-safeguard mechanisms set in place for the species.Methods:We tracked 30 ETF Bar-headed Geese from Chinese and Mongolian breeding areas to their wintering grounds using GPS/GSM transmitters,to determine their migration routes and stopover staging patterns within the QTP,overlaying these upon GIS layers of protected area status and habitat type,to model their habitat selection.Results:In total,14 tagged Bar-headed Geese provided information on their entire autumn migration and 4 geese on their entire spring migration.Qinghai Lake marked birds overwintered in the QTP(n=2),geese tagged in Mongolia wintered either in the QTP(n=3)or in India/Bangladesh(n=9),representing three of the migration routes within the ETF.In total,tagged birds staged at 79 different stopover sites within QTP in autumn and 23 in spring,of which 65%(autumn)and 59%(spring)of all fixes fell within the boundaries of either National Nature Reserves(NNRs)or Important Birds Areas(IBAs)in the QTP.Bar-headed Geese predominantly occurred on four land-cover types:grassland(mostly by day),water bodies(at night),wetlands and bare substrates(salt flats,dry lake/river substrates and plough)with little change in proportion.Generalized linear mixed models comparing presence with pseudo-absence data suggested geese strongly selected for wetlands as staging habitat,avoiding bare substrates in spring.Conclusions:Based on our limited observations of these tagged geese,this study is the first to show that the current designated National Nature Reserves in place in the staging areas within the QTP appear adequate to protect this increasing population.In addition,Hala Lake in Qinghai Province and adjacent areas used as initial QTP staging during autumn migration(currently outside of designated as NNRs/IBAs)are recommended for protection,based on their use by tagged birds from this study.Habitat modelling confirmed the importance of natural wetlands as feeding areas and safe areas of open water as roosting places.

Migration routes,behavior and protection status of Eurasian Spoonbills(Platalea leucorodia)wintering in China

Background:The Eurasian Spoonbill(Platalea leucorodia)occurs throughout Eurasia and North and sub-Saharan Africa,with three recognized subspecies and six geographically distributed populations.However,in China,we knew almost nothing about migration routes,habitat use and effectiveness of current site protection measures for this species.Methods:We deployed Global Positioning System/Global System for Mobile Communications(GPS/GSM)satellite trackers on 29 Eurasian Spoonbills captured in summer in Mongolia and northeastern China,to obtain complete migration routes data from 10 individuals from 19 complete migration episodes.Results:Tracking data showed no geographical overlap during the annual cycle in Eurasian Spoonbills marked in the two main summering areas.Birds marked in the Naoli River Basin in Heilongjiang Province,China,wintered along the Jiangsu coastline in China,while Eurasian Spoonbills from two discrete summering areas(in Inner and western Mon-golia)overwintered inland in the Yangtze River floodplain of China.Excluding the single Inner Mongolian bird,spring migration was significantly faster than autumn migration in the other two groups of birds.Eurasian Spoonbills mainly used water,wetland and grassland habitats in summer,but almost exclusively water in winter.Lack of protection of staging sites used by all the birds in spring and poor levels of protection throughout the annual cycle for western Mongolian birds(5-22%)gives considerable cause for concern,although sites used in other time by East Mongolian and Naoli River birds in the rest of their annual life cycle enjoyed good levels of protection(49-95%).Conclusions:These results revealed previously unknown relationships between summering and wintering areas,migration routes and stopover sites for Eurasian Spoonbills wintering in China,suggesting the existence of discrete biogeographical population units.They also identified winter habitat use of Eurasian Spoonbills in China,confirming open water habitats as being critical throughout the annual cycle,although based on small sample size,gaps in cur-rent site safeguard networks for these populations.

Seasonal and regional differences in migration patterns and conservation status of Swan Geese(Anser cygnoides)in the East Asian Flyway

Background:The Swan Goose(Anser cygnoides)breeds across Mongolia and adjacent China and Russia and winters exclusively in China.It is globally threatened,showing long-term major range contractions and declining abundance,linked to habitat loss and degradation.We remain ignorant about the biogeographical subpopulation structure of the species and potential differences in their migration timing,stopovers and schedules,information that could be vital to effective conservation of different elements of the species population,which we address here with results from a telemetry study.Methods:In 2017-2018,we attached GPS/GSM telemetry devices to 238 Swan Geese on moulting sites in three discrete parts of their summering area(Dauria International Protected Area,Central Mongolia and Western Mongolia),generating 104 complete spring and autumn migration episodes to compare migration speed and nature between birds of different summer provenances.Results:Birds from all three breeding areas used almost completely separate migration routes to winter sympatrically in the Yangtze River floodplain.Although many features of the spring and autumn migrations of the three groups were similar,despite the significantly longer migration routes taken by Western Mongolian tagged birds,birds from Dauria Region arrived significantly later in winter due to prolonged staging in coastal areas and took longer to reach their breeding areas in spring.Among birds of all breeding provenances,spring migration was approximately twice as fast as autumn migration.Areas used by staging Swan Geese(mainly wetlands)in autumn and spring almost never fell within national level protected areas,suggesting major site safeguard is necessary to protect these critical areas.Conclusions:This study showed the discreteness of migration routes taken by birds of different summer provenances and differences in their migratory patterns,highlighting key staging areas(Yalu River Estuary in China/North Korea for Dauria Region breeding birds,Daihai Lake for Central Mongolian and Ordos Basin for Western Mongolian birds).Based on this new knowledge of the biogeographical subpopulation structure of the Swan Goose,we need to combine data on subpopulation size,their distribution throughout the annual life cycle and conservation status,to develop more effective conservation strategies and measures to reverse population decline throughout the range.

Variability among autumn migration patterns of Mongolian Common Shelducks(Tadorna tadorna)

Background:Avian migrants moving between common breeding and wintering areas may adopt different migration routes,and consequently affect timing.However,this pattern has rarely been investigated,especially in waterbirds.Moreover,autumn migration patterns of the Common Shelduck(Tadorna tadorna) have never been studied.Methods:We used GPS transmitters to track,for the first time,the autumn migration of the Common Shelduck in East Asia(n = 14).Results:The Common Shelduck undertook a broadly northwest–southeast autumn migration,taking a mean of 91.7 ± 38.7(SD) days to cover a mean distance of 1712.9 ± 450.5 km at a speed of 89.4 ± 226.5 km/day.The birds used 2.5 ± 1.8 stopover sites,and the total stopover duration was 81.9 ± 38.7 days.There were considerable betweenindividual variations in the onset(24 August to 28 September) and completion(29 September to 11 January) of migration,distance(1070.2–2396.4 km),speed(14.7-734.0 km/day),the index of straightness(0.6-1.0),duration(1.5-151.8 days),stopover times(0-5) and total stopover durations(0-148.1).More direct migration routes were associated with fewer and shorter stopovers(p = 0.003 in both cases).Post-breeding and wintering site habitat use was similar between individuals,whereas stopover site habitat use varied considerably within and between individuals.Conclusions:Our study showed remarkable variability in Shelduck migration patterns,which was likely associated with refuelling patterns en route.To understand fully the migration diversity and flexibility of habitat-use,we need to track more birds to increase representativeness,using accelerometer-integrated transmitters to investigate behaviours in different habitats.

Integrating Wintering Waterbird Movements with Earth Observation Data of Wetland Dynamics

Wetlands are among the most productive and essential ecosystems on earth,but they are also highly sensitive and vulnerable to climate change and human disturbance.One of the current scientific challenges is to integrate high-resolution remote sensing data of wetlands with wildlife movements,a task we achieve here for dynamic waterbird movements.We demonstrate that the White-naped cranes Antigone vipio wintering at Poyang Lake wetlands,southeast of China,mainly used the habitats created by the dramatic hydrological variations,i.e.seasonal water level fluctuation.Our data suggest that White-naped cranes tend to follow the water level recession process,keeping close to the boundary of water patches at most of the time.We also highlight the benefits of interdisciplinary approaches to gain a better understanding of wetland ecosystem complexity.

基于卫星追踪探讨黄河流域自然保护区对3种水鸟栖息地的保护现状

自然保护区是生物多样性保护的重要形式,对于迁徙水鸟而言,它的规划尤为重要。本研究于2016–2018年间在中国、蒙古国和俄罗斯捕捉6只斑头雁(Anser indicus)、5只白琵鹭(Platalea leucorodia)和10只东方白鹳(Ciconia boyciana)进行卫星追踪,探讨了黄河流域自然保护区对它们栖息地的保护现状。基于4年累积获取的844,592条高频数据,分析了这21只水鸟在黄河流域活动的时间和利用的土地类型,并使用核密度法拟合了3种鸟类的家域。结果表明:3种鸟类均利用黄河流域湿地作为迁徙途中的停歇地,其中一部分白琵鹭幼鸟利用黄河流域湿地作为度夏地,一部分东方白鹳利用黄河三角洲湿地作为越冬地;3种水鸟在黄河流域内的土地利用情况存在差异,斑头雁对草地(49.0%)、裸地(26.2%)与水体(22.5%)的利用率较高,白琵鹭对农田(42.1%)、草地(19.8%)和湿地(19.6%)的利用率较高,东方白鹳对湿地(49.8%)、农田(34.5%)和水体(4.6%)的利用率较高;斑头雁核心的50%家域被现有保护区完全覆盖,而白琵鹭和东方白鹳核心的50%家域被现有保护区的覆盖度分别为1.6%和0,表明后2种水鸟的栖息地极大可能存在保护空缺;同时对覆盖范围内土地类型自身占比进行分析,发现3种鸟类对于裸地、草地和农田的利用偏向于被动选择,而对于湿地和水体的利用表现为主动选择。基于卫星追踪获得的高频数据可以准确反映3种水鸟在黄河流域的停歇情况、土地利用情况及潜在栖息位点。在黄河流域自然保护区的进一步规划中,应关注白琵鹭和东方白鹳适宜生境的保护状况,并建立覆盖全面的保护区。

Consistent habitat preference underpins the geographically divergent autumn migration of individual Mongolian common shelducks

While many avian populations follow narrow,well-defined"migratory corridors,"individuals from other populations undertake highly divergent individual migration routes,using widely dispersed stopover sites en route between breeding and wintering areas,although the reasons for these differences are rarely investigated.We combined individual GPS-tracked migration data from Mongolian-breeding common shelduck Tadorna tadorna and remote sensing datasets,to in-vestigate habitat selection at inland stopover sites used by these birds during dispersed autumn migration,to explain their divergent migration patterns.We used generalized linear mixed models to investigate population-level resource selection,and generalized linear models to investigate stopover-sit-level resource selection.The population-level model showed that water recurrence had the strongest positive effect on determining birds'occupancy at staging sites,while cultivated land and grassland land cover type had strongest negative effects;effects of other land cover types were negative but weaker,particularly effects of wwater seasonality and presence of a human foot-print,which were positive but weak or non-significant,respectively.Although stopover-site-level models showed variable resource selection patterns,the variance partitioning and cross-prediction AUC scores corroborated high inter-individual consistency in habitat selection at inland stopover sites during the dispersed autumn migration.These results suggest that the geographically wide-spread distribution(and generally rarity)of suitable habitats explained the spatially divergent autumn migrations of Mongolian breeding common shelduck,rather than the species showing flexible autumn staging habitat occupancy.

Annual migratory patterns of Far East Greylag Geese(Anser anser rubrirostris)revealed by GPS tracking

Twenty Far East Greylag Geese,Anser anser rubrirostris,were captured and fitted with Global Positioning System/Global System for Mobile Communications(GPS/GSM)loggers to identify breeding and wintering areas,migration routes and stopover sites.Telemetry data for the first time showed linkages between their Yangtze River wintering areas,stopover sites in northeastern China,and breeding/molting grounds in eastern Mongolia and northeast China.10 of the 20 tagged individuals provided sufficient data.They stopped on migration at the Yellow River Estuary,Beidagang Reservoir and Xar Moron River,confirming these areas as being important stopover sites for this population.The median spring migration duration was 33.7 days(individuals started migrating between 25 February and 16 March and completed migrating from 1 to 9 April)compared to 52.7 days in autumn(26 September-13 October until 4 November-11 December).The median stopover duration was 31.1 and 51.3 days and the median speed of travel was 62.6 and 47.9 km/day for spring and autumn migration,respectively.The significant differences between spring and autumn migration on the migration duration,the stopover duration and the migration speed confirmed that tagged adult Greylag Geese traveled faster in spring than autumn,supporting the hypothesis that they should be more time-limited during spring migration.