Autumn migration routes and wintering areas of juvenile Chinese Egrets(Egretta eulophotes)revealed by GPS tracking

Background:The vulnerable Chinese Egret(Egretta eulophotes)is a long-distance migratory waterbird whose migration and wintering information is poorly understood.This study aims to identify the autumn migration routes and wintering areas of juvenile Chinese Egrets and determine the migration movement traits of this species.Methods:Thirty-nine juvenile Chinese Egrets from the Fantuozi Island,an uninhabited offshore island with a large breeding colony of Chinese Egrets in Dalian,China,were tracked using GPS/GSM transmitters.Some feathers from each tracked juvenile were collected for molecular identification of sex in the laboratory.The GPS locations,recorded at 2-h intervals from August 2018 to May 2020,were used for the analyses.Results:Of the 39 tracked juveniles,30 individuals began their migration between September and November,and 13 successfully completed their autumn migration between October and November.The juveniles migrated southward via three migration routes,coastal,oceanic and inland,mainly during the night.The migration duration,migration distance,flight speed,and stopover duration of the 13 juvenile egrets that completed migration averaged 5.08±1.04 days,3928.18±414.27 km,57.27±5.73 km/h,and 23.08±19.28 h,respectively.These juveniles wintered in the coastal wetlands of Southeast Asia including those in the Philippines,Vietnam,and Malaysia,and only one successfully began its spring migration in June 2020.Conclusions:This study newly finds that the oceanic route taken by juvenile Chinese Egrets,suggesting that the juveniles are able to fly over the Pacific Ocean without a stopover.Moreover,our novel data indicate that coastal wetlands along the East Asian-Australasian Flyway are important areas for both autumn migration stopover and the wintering of these juveniles,suggesting that international cooperation is important to conserve the vulnerable Chinese Egret and the wetland habitats on which it depends.

Shifts in phenology of autumn migration and wing length among reedbed passerines along the East Asian–Australasian Flyway

Climate change impacts bird migration phenology,causing changes in departure and arrival dates,leading to potential mismatches between migration and other key seasonal constraints.While the impacts of climate change on arrival at breeding grounds have been relatively well documented,little is known about the impacts of climate change on post-breeding migration,especially at stopover sites.Here we use long-term(11 years)banding data(11,118 captures)from 7 species at Mai Po Marshes Nature Reserve in Hong Kong,a key stopover site for migratory birds along the East Asian–Australasian Flyway,to describe long-term changes in migration phenology and to compare observed changes to annual weather variation.We also examine changes in wing length over a longer time period(1985–2020)as wing length often correlates positively with migration distance.We found that observed changes in migratory phenology vary by species;three species had later estimated arrival(by 1.8 days per year),peak(by 2.6 days per year)or departure(by 2.5 days per year),one showed an earlier peak date(by 1.8days per year)and two showed longer duration of passage(2.7 days longer and 3.2 days longer per year).Three species exhibited no long-term change in migration phenology.For two of the four species with shifting phenology,temperature was an important predictor of changing peak date,departure dates and duration of passage.Wing length was shorter in three species and longer in two species,but these changes did not correlate with observed phenological changes.The complex changes observed here are indicative of the challenges concerning the detection of climate change in migratory stopover sites.Continued monitoring and a better understanding of the dynamics of all sites in the migratory pathway will aid conservation of these species under global change.

Migration routes of the endangered Oriental Stork(Ciconia boyciana)from Xingkai Lake,China,and their repeatability as revealed by GPS tracking

The Oriental Stork(Ciconia boyciana)is listed as'Endangered'on the International Union for the Conservation of Nature(IUCN)Red List of Threatened Species and is classified as a first category nationally protected bird species in China.Understanding this species'seasonal movements and migration will facilitate effective conservation to promote its population.We tagged 27 Oriental Stork nestlings at Xingkai Lake on the Sanjiang Plain in Heilongjiang Province,China,used GPS tracking to follow them over the periods of 2014-2017 and 2019-2022,and confirmed their detailed migratory routes using the spatial analysis function of ArcGIS 10.7.We discovered four migration routes during autumn migration:one common long-distance migration route in which the storks migrated along the coastline of Bohai Bay to the middle and lower reaches of the Yangtze River for wintering,one short-distance migration route in which the storks wintered in Bohai Bay and two other migration routes in which the storks crossed the Bohai Strait around the Yellow River and wintered in South Korea.There were no significant differences in the number of migration days,residence days,migration distances,number of stopovers and average number of days spent at stopover sites between the autumn and spring migrations(P>0.05).However,the storks migrated significantly faster in spring than in autumn(P=0.03).The same individuals did not exhibit a high degree of repetition in their migration timing and route selection in either autumn or spring migration.Even storks from the same nest exhibited considerable between-individual variation in their migration routes.Some important stopover sites were identified,especially in the Bohai Rim Region and on the Songnen Plain,and we further explored the current conservation status at these two important sites.Overall,our results contribute to the understanding of the annual migration,dispersal and protection status of the endangered Oriental Stork and provide a scientific basis for conservation decisions and the development of action plans for this species.

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.