Wintering home range and habitat use of the whooper swans (Cygnus cygnus) in Sanmenxia Wetland, China

Home range and habitat use are the central components of avian ecology, and studies on these aspects will be helpful for the conservation and management of avian populations. Sixty-seven swans were global positioning system tagged at Sanmenxia Wetland of Henan Province to obtain detailed location data in winter from 2015 to 2016. The home range size of swans was the largest in the middle wintering period and followed by the early period and late period, and sizes were significantly different among the three wintering periods. There were significant differences in habitat use among the different wintering periods. In the early period, the swans mainly used the aquatic grasses and emergent plants zones, and they mainly relied on artificial supplementation because of a lack of natural feeding habitats in the middle period. In the late period, the swans mainly used the newly emerged terrestrial grasses zone. Except for the deep water, the use of other water levels was significantly different among the different wintering periods. In the early wintering period, the swans tended to prefer the low and high water level areas; in the middle period, they were mainly in the intermediate and high water level areas and they used all the water level areas except the deep water level in the late wintering period. It was concluded that some plants are preferred by the swans, such as reeds, cattails and barnyard grass, and that water depth should be suitable for the swans, with the water levels varying over a gradient.