Influence Of Landscape Pattern Changes On The Habitat Selection Of Tundra Swan During Winter In Poyang Lake

Poyang Lake was a unique hydrological environment,with warm and humid climate.It could provide rich food resources for wintering migratory birds.It was an important wintering ground for waterbirds such as Tundra Swans,which was a great significance to protect migratory birds along the East Asia-Australia migration route.This paper compared the characteristics and changes of Poyang Lake landscape pattern in different years and different time phases,which based on the Landsat 8 remote sensing image data of the third phase of Poyang Lake in the winter of 2015-2016.Satellite tracking of 15 Tundra Swans had been executed,and their home range and habitat selection had been further studied.There were some following conclusions obtained:1.In the same year,the landscape pattern in different periods was significantly affected by the water level.In the same time phase,the landscape types of Poyang Lake for diverse years would also undergo a greater shift.Compared with February of 2016 and February of 2015,the area of mudflats and grassland had decreased,but the water area increased.The change of water level was the main driving factor that promoted the landscape pattern of Poyang Lake changes.Overall,the areas of water area and water level were positively correlated,while the areas of the mudflats and grassland were negatively correlated with water level.2.The home range of Tundra Swans over wintering in Poyang Lake was quite different.However,the inter-annual home range(F=0.032,P=0.862)and nuclear area(F=0.056,P=0.818)were not significantly increase or decrease.For different Tundra Swan,their nuclear area only occupied a small part of their home range.Under altered water levels,the composition of wetland landscape in Tundra Swan's home area was different.However,its overall home area included mudflats,water areas and grasslands.And the core home area was generally near the water area.3.The Tundra Swan in Poyang Lake presented the characteristics of regional gathering and distribution.In the year of low-water level,Tundra Swans were mainly active in deep water lakes such as the main lake area.While in the year of high-water level,it was mainly active in the dish-shaped lake in the southwest.Therefore,with the change of water level,Tundra Swans changed the habitat selection.In years of highwater level,the main habitat of Tundra Swans,during the wintering period turned from water to grasslands;In years of low-water level,Tundra Swans preferred to move in the water body.But,under different water levels,there was no difference in the choice of Tundra Swan's day and night habitat(7.58 meters: t=0.000,df=3,P=1.000;12.22meters: t=0.000,df=3,P=1.000;10.86 meters: t=0.000,df=3,P=1.000).4.The daily activity range of the Tundra Swans in the high-water year was extremely significantly larger than the low-water year(U=39071.000,Z=-4.832,P=0.000);However,during the same overwintering period,the change of water level would have a certain degree of influence on the Tundra Swans' daily activity range,but there was no significant correlation.