The Distribution And Population Size And Trend Of Oriential Stork(Ciconia Boyciana) And The Habitat Selection Of The Overwintering Group In Bohai Bay

The Oriental Stork is an endangered species in the world,and it is also a national first-level protected wild animal.Based on the data of satellite tracking,overwintering surveys and literatures,this paper updates the distribution range of breeding and overwintering sites for the distribution map provided by Birdlife International of Oriental Stork and calculates the population size and trend in 2020.In addition,the habitat selection,activity range and protection status of the short-distance migrating overwintering population in Bohai Bay are illustrated.The main results are as follows:The Oriental Stork is divided into a wild population and a captive breeding population.The Captive-bred non-migratory population is distributed in Japan,where this paper preserves the wintering range recommended by Birdlife International.The wild population breeds in Northeast China and Russian Far East,and winters mainly in China,with a few in South Korea.Based on the original breeding areas(Russian Far East,Songnen Plain and Sanjiang Plain in Northeast China),this study expands the wetland areas of Russian Primorsky Krai,the eastern Songnen Plain and the western Sanjiang Plain in Northeast China;adds coastal areas in Hebei Province(Tangshan Fengnan District),Tianjin City(Jinghai District),Shandong Province(Yellow River Delta),Jiangsu Province(Gaoyou City and Dafeng Milu Reserve)and other areas;Inland regions such as the Yangtze River Basin(Poyang County,Yogan County and Jinxian County)in Jiangxi Province and Wangjiang County in Anhui Province are added.The inland areas in China of original wintering areas(southeastern China,Taiwan,and South Korea)are reduced to Hunan Province,Hubei Province,Jiangxi Province,Anhui Province,Jiangsu Province,and Shanghai in the middle and lower reaches of the Yangtze River Basin;the Liaohe Estuary area and the southern part of the Liaodong Peninsula are added to the coastal wintering areas,however the wintering areas in other coastal areas are reduced to Yancheng City,Jiangsu Province,Chongming Dongtan and Nanhui Dongtan in Shanghai,and the Mi Pu Reserve in Hong Kong.The coastal area in the northeast corner of South Korea are added.the latest estimate of the wild population of Oriental Storks is about 6,300individuals based on the field survey data from 2018 to 2021,compared to c.3000 in2012,the number show that a significant upward trend with increases in both China(c.6000)and South Korea(c.300).The artificial breeding population numbers c.100 in Japan,which is on the rise compared with 5 in 2012.There are two migration routes for the wintering population of the Oriental Stork in China.One is the long-distance migration population that overwinters in the Yangtze River,and the wintering population numbers c.5700,another is the short distance migration population that overwinters in Bohai Bay and its surrounding areas,the overwintering populations numbers c.300.The two populations can use common breeding grounds,and some individuals can use different wintering areas in different years.Distribution characteristics of long distance migratory populations of Oriental Stork during the wintering period in the middle and lower reaches of the Yangtze River:They were mainly distributed in Poyang Lake and Anhui Lake Group in Jiangxi.Comparison of key sites(1%=60)between 2017/2018-2019/2020 and2003/2004-2004/2005 showed that the wintering areas of the species were concentrated in Poyang Lake,Shengjin Lake,Caizi Lake,Wuchang Lake and Chenyao Lake,and the population in these areas was also increasing,but the habitat of Huangdahu Lake has faded.The distribution of Oriental Storks in Poyang Lake(the most important wintering area)is becoming more and more widespread,mainly concentrated on the west and southwest bank of Poyang Lake.The results indicate that the wintering area of the Oriental Stork in the Yangtze River wetland has not increased significantly,but the distribution density in key sites has increased significantly.Korean-wintering Oriental Storks wintering in Inchon,South Chungcheong,North Jeollanam and South Jeollanam provinces.Based on the 2020/21overwintering survey,there are 13 key overwintering loci(1%=3)in South Korea,mainly distributed in the western coastal areas.The short-distance migratory population of Oriental Stork overwintered in Bohai Bay from mid to late November to late April.The individual overwintering period was 146±32(mean±standard deviation)days.The overlays of overwintering(N=14)daytime foraging site data and Google Earth images in 2020 revealed that the species mainly used reclamation areas and natural freshwater wetlands in the non-glacial period during the overwintering period,while the species mainly used reclamation areas such as fish ponds,shrimp ponds and salt fields in the glacial period.Although Oriental Stork overwinters in Bohai Bay,it uses inland freshwater wetlands instead of coastal tidal flats for foraging,which indicating that this species is a typical freshwater species.The short-distance migratory Oriental Stork population of overwintering in Bohai Bay area,overwintering in Liaohe Estuary of Liaoning Province,southern Liaodong Peninsula,Caofeidian District of Tangshan,Hebei Province and Yellow River Delta of Shandong Province.The key sites of overwintering were in Caofeidian area of Tangshan,Hebei Province and Yellow River Delta of Shandong Province.The core distribution area of the wintering land was analyzed by the kernel density method.The results showed that 50%of the core home range was 2,008.4 km~2,and 90%of the core home range was 16,171.9 km~2.In the above four wintering areas:Shuangtai Hekou National Nature Reserve in Liaoning,Dalian Spotted Seal National Nature Reserve in Liaoning,and Yellow River Delta National Nature Reserve in Shandong(there is no national nature reserve in Caofeidian District in Tangshan,Hebei),the proportion of Oriental White Storks protected are:10.7%in Liaohe Estuary and Liaodong Peninsula in Liaoning,2.5%in Yellow River Delta in Shandong,and 0%in Caofeidian District in Tangshan,Hebei(there is no national protection area).This indicates that the protection proportion of short-distance migratory groups in the wintering ground is low.In conclusion,this research is the first to update the distribution range of Oriental Stork,illustrates the species population trends,analysis wintering habitat choice behavior model and home range of the bohai bay wintering population,at the same time also probes into the factors that increase the number of species,these results provide a scientific basis for the Oriental Stork protection and management in reproduction and wintering sites.