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.

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.

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.