Study On The Migration Routes And Stopover Sites Of Oriental Stork Wintering In Poyang Lake Based On Satellite Tracking

Oriental Stork(Ciconia boyciana)an endangered large wading bird of the world,belongs to Ciconiidae of Ciconiformes.It is a national first-class key protected wild animal.At present,the research methods on the migration of Oriental Stork are mainly by historic manual survey or inferred by their stopover sites,wintering and nesting sites.Although satellite tracking technology is now available,related data collected are very few.According to the existing research literatures,studies on migration and stopover sites of Oriental Stork mainly focus on breeding individuals in summer,and mostly focus on the autumn migration pattern.Few scholars had conducted detailed studies on the overall migration process of Oriental Stork wintering in Poyang Lake.In this study,we carried out a banding programme of Oriental Storks wintering in Poyang Lake,and installed satellite tracking devices to study the migration,in order to discover their stopover sites,summering sites,migration routes and migration characteristics,thus filling the blank of research on Oriental Storks that are wintering in Poyang Lake.(1)From December 2016 to March 2020,14 Oriental Storks were banded and tracked by satellite at Caofeidian Area of Tangshan City of Hebei Province,and the Poyang Lake Nanji Wetland National Nature Reserve of Jiangxi Province,42 complete migration routes(including28 spring migration routes and 14 autumn migration routes)were obtained.The average start date of spring migration of Oriental Stork was March 26 and the average end date was April 28.The average migration duration was 33.36 d and the average migration distance was 3360 km,and the average migration speed was 122.47 km/d.The average start date of autumn migration was October 30,and the average end date was November 30.The average migration duration in autumn is 33.07 d,the average migration distance is 3001.46 km,and the average migration speed is 95.20 km/d.There were no significant differences in migration time,migration distance and migration speed between spring and autumn.(2)To track the sea crossing of Oriental Stork,it generally migrates along the coastal bay of the Bohai Sea.In autumn,Oriental Stork always migrates around the coastal bay of the Bohai Sea to reach the wintering ground.In the spring,three individuals chose to migrate across Bohai Gulf.(3)Tracking results revealed that Oriental Storks generally fly in the day during migration,only occasionally migrate at night.In spring,the instantaneous flight speed of Oriental Stork is usually 30～40km/h,but the instantaneous flight speed of 40～50km/h is the most frequent in autumn.The highest instantaneous velocity of Oriental Stork by tracking during spring migration is 116.8km/h locating near the Liaohe River,while the highest instantaneous velocity during autumn migration is 92km/h in the Yellow River Delta.The flight frequency of Oriental Stork was higher from 6:00 to 19:59,and decreased sharply from 20:00 to 5:59 in spring,however,the flight frequency of Oriental Stork was higher from 7:00 to 17:59,and decreased sharply from17:00 to 6:59 in autumn.The active time of Oriental Stork in spring was 3 hours more per day than that in autumn.It could be caused by birds coping with breeding pressure in the spring and earlier spring sunrise.(4)From 2016 to 2019,the average temperature was 11℃ when Oriental Storks arrived at the breeding site,and the minimum temperature was 2℃,and they left the breeding sites when the average temperature drop below 4℃,and the lowest temperature was-2℃ while the highest temperature was below 16.5℃.From 2016 to 2018,the average temperature was 3.8℃ when Oriental Storks arrived at the wintering ground,with a minimum temperature of-6.5℃.When the average temperature rose above 8.2 ℃,Oriental Stork left for north,and the lowest temperature was 3℃ and the highest temperature was lower than 13℃.There was no significant correlation between the migration time and the temperature.(5)The tracking results also showed that Oriental Storks use 283 spring stopover sites and173 autumn stopover sites,in which 162 sites were reused more than 2 times respectively.Important stopover sites in spring includes Beidagang Reservoir in Tianjin,old river bed of Yellow River in Dongying of Shandong Province,Wuchang Lake in Wangjiang County of Anhui Province,and coastal aquaculture ponds in Cangzhou of Hebei Province;and the important stopover sites in autumn are Shengjin Lake and Caizi Lake in Anqing City,Anhui Province,Caofeidian aquaculture ponds in Hebei Province,and Nenjiang River bank in Zhenlai County of Baicheng City,and Longfengshan Reservoir in Songyuan City of Jilin Province.(6)In spring,river(24%),marsh(24%),farmland(13%)were the main habitat types for stopover sites,and in autumn,river(26%),marsh(21%)and reservoir(21%)were the main types of stopover sites.Compared with autumn,Oriental Storks utilize more habitat types in spring migration.(7)From the tracking results,Oriental Storks roost mainly in Songnen Plain and Sanjiang Plain in summer,but some of them choose to roam in Notheast China during breeding period.This phenomenon implys Oriental Storks may trying looking for suitable habitat,or be related to its participation in breeding.