The Study Of Stopover Waterbirds On Community Composition And Habitat Utilization During The Migratory Periods In The Beilun Estuary Nature Reserve Guangxi Province

From October 2016 to May 2017,a survey of stopover conditions of migratory waterbirds communities in Beilun Estuary Reserve and surrounding wetlands was carried out.The community of waterbirds in the study area was investigated in detail by using the model of point,line and area.This paper analyzed the composition of waterbirds community during the stopover period,and determining the key areas and important habitats of their stopover sites,exploring.the effects of environmental factors on the stopover conditions of waterbirds in the nature reserve.Besides,this paper put forward some protective suggestions for the development and construction of the nature reserve and its surrounding areas.Research results as follows:1.The Beilun Estuary National Nature Reserve in Guangxi is an important stopover sites for migratory waterbirds.There are 66 species of waterbitds in the migration period,belonging to 7 orders and 12 families,and the number of them is more than 10000.Among them,Pacific Reef-Egret(Egretta sacra),Whooper Swan(Cygnus cygnus)and Nordmann's Greenshank(Tringa guttifer)on the list of the second-class protection bird of China,and the proportion of protected animals is 93.9%.The IUCN focuses on 7.5%,including Nordmann's Greenshank(EN)and Spoon-billed Sandpiper(Eurynorhynchus pygmeus,CR).44 species(66.67%)list on the China-Australia Migratory Bird Agreement,29 species(43.94%)list on the China-Japan Migratory Bird Agreement.2.Black-headed Gull(Chroicocephalus ridibundus),Kentish Plover(Charadrius alexandrinus),Little Egret(Egretta garzetta)is the dominant species in the reserve.There are 12 common species including Black-winged Stilt(Himantopus himantopus),Dunlin(Calidris alpina),Lesser Sand Plover(Charadrius mongolus),Whiskered Tern(Chlidonias hybrida),The rare and endangered birds are rare species,such as Spoon-billed Sandpiper,Nordmann's Greenshank,Pacific Reef-Egret,Whooper Swan and so on.According to the previous records,the Beilun Estuary Reserve has new record of endangered rare birds every year,so this reserve is an important stopover area of endangered rare birds.3.30 species of waterbirds with high dominance such as Black-headed Gull,Little Egret,Kentish Plover,Common Greenshank(Tringa nebularia),Black-winged Stilt,Marsh Sandpiper(Tringa stagnatilis)reach the reserve in the autumn migration season,all of them can be recorded during the migration period.Most of them overwintering in the reserve is mainly concentrated in the Jintan area,Rongshutou area,Kexi area and Jiaodong area.Such as Temminck's Stint(Calidris temminckii),Terek Sandpiper(Xenus cinereus),Purple Heron(Ardea purpurea),Whimbrel(Numenius phaeopus),Grey-headed Lapwing(Vanellus cinereus)and Common Redshank(Tringa totanus),are fixed to the reserve for sotpover during the north and south migration,and they do not wintering in the reserve.Such as Bar-tailed Godwit(Limosa lapponica),Spoon-billed only stopover in the reserve when it moves southward in the autumn.White-winged Tern(Chlidonias leucopterus),Striated Heron(Butorides striata)and other waterbirds only stopover in the reserve when moving northward in the spring.Oriental Pratincole(Glareola maldivarum)were recorded at the end of the spring migration season and were observed to breed in sandy of the Gongyeyuan area.4.During the autumn migration season,the number of waterbird species changed significantly,the peak was in November.Nearly 4000 waterbirds belongs to about 50 species arrived in Beilun Estuary Reserve to stopover,mainly in the Jiabang area,Kexi area and Rongshutou area.In spring migration period,nearly 5000 water birds arrived in the reserve to stopover,and the number was more than autumn migration period,but the richness was slightly less than autumn migration period,represented by Whiskered Tern and Intermediate Egret(Egretta intermedia),the peak was in March.It mainly focuses on Rongshutou area,Kexi area,Jiabang area,Gongyeyuan area and Jiaodong area.5.Rongshutou area,Kexi area and Jiabang area have high biological capacity and are highly similar to each other,and they are the main stopover areas for the migration waterbirds.The habitat of the Jintan area is mainly beaches,the species of waterbirds is a little less,there is a special stopover sites for waterbirds such as Spoon-billed Sandpiper,Terek Sandpiper,Sanderling(Calidris alba),Bar-tailed Godwit,Grey-tailed Tattler(Larus crassirostris),Saunders' s Gull(Tringa brevipes),Black-tailed Gull(Chroicocephalus saundersi),Broad-billed Sandpiper(Limicola falcinellus).The biological capacity of Jiaodong area and Gongyeyuan area is less than others,but Gongyeyuan area was the main stopover area for Whiskered Tern and Intermediate Egret.6.The habitats of waterbird's stopover in the reserve are mainly natural wetlands,such as mud flat,sandy intertidal zone,estuary beach and so on.Secondly,it is artificial wetlands such as pond.Grassland swamp habitat is the main stopover habitat for non-waders migratory waterbirds.7.The microhabitats such as sandy land,trees,farmland and duck farm provide a richer activity level for the stopover of the waterbird,meet the habitat needs of their different activities,and also provide temporary habitat for the birds when the main stopover habitat is affected.Mangrove habitats s a special stopover sites for herons.8.The number of stopover birds in the reserve is affected by tidal conditions and weather changes.The level of tidal level directly affects the number of waterbird recorded,and the number of waterbirds recorded at high tide level is more.The change of temperature has a significant effect on stopover waterbird's number,the lower the temperature,the greater the number of waterbirds.Tidal direction also affects the number of waterbirds.9.The behavior of stopover birds in the reserve is affected by tidal conditions and weather changes.At high tide level,water birds choose to rest,and at low tide they choose to forage and move;compared with ebb tide,water birds are more active at flood tide;In fine weather,water birds are more active in activities and foraging,but in cloudy and rainy days they are less active.10.The effect of tidal and weather factors on stopover condition of waterbird is more obvious in Kexi area,Rongshutou area and Jintan area.In addition,the number of waterbirds in Kexi area increased in non-strong windy day;The stopover waterbird in Jintan area and Kexi area were more active in the late afternoon than in the morning.11.The number of waterbirds in ditches,sea surface and mudflats decreases with the increase of the tide level.The number of waterbirds in dyke and pond increases with the increase of tidal level.The individual number of waterbirds in pond also increases with the increase of temperature.The individual number of waterbirds in the stony shoals increased in the afternoon.In Grassland swamp and ditches,as temperatures rise,more waterbirds actived in activities and foraging;In artificial habitats,such as pond and dyke,the activity of waterbirds is reduced on rainy days;and in mangrove habitats,the stopover herons are more active in the morning because they are affected by human activities.