Abstract:

Objective: This study aims to document differences in movement pattern and habitat use between high water years and normal water years of Siberian Cranes wintering in Poyang Lake, to benefit crane conservation and adaptive habitat management. Method: Water level data of Xingzi Hydrological Station and tuber biomass of food plant Vallisneria spp. for Siberian Cranes were used to define the different water years. The years of 2016 and 2017, and 2020 and 2021 were defined as high water years, and the first two years were referred as group-W1 and the later as group-W3. While, the years of 2018 and 2019 were defined as normal years or referring as group-W2. Thirteen Siberian Cranes were tracked with satellite transmitters in Poyang Lake from 2016 to 2022. Differences were determined and analyzed with ArcGIS 10.7 in movement distances, home range areas and habitat use of Siberian Cranes between the high water and the normal groups. Result: 1) The Siberian Cranes in the whole winter and in mid-winter moved significantly less during normal years (W2) than those of high water years W1, or W3, or combined. 2) 90% KDE in the three winter periods during the high water years (W1 and W3) were significantly larger than those in the normal years (W2). In mid-winter, home ranges of 90% and 50%KDE in the high water years W1 was significantly larger than those in the normal years (W2) and high water years W3. 3) In normal years (W2), the overall use of wetland in daytime accounts for 89.0% ± 12.3% (n = 9). The use of farmland by the cranes in the whole winter, and in early and middle winters in high water years were significantly higher than those in normal water years (W2). The wetland use in high water years was significantly lower than in normal years, in spite of accounting for 50.4% ± 20.5% (n = 15). There was no significant difference in farmland use or wetland use by the cranes among groups in high water years. In normal years (W2), the overall use of wetland in nighttime accounts for 94.9% ± 8.7% (n = 9); In high water years, the overall use of wetland in night time about 84.5% ± 18.4%（n = 15）. The use of farmland by the cranes in middle winters in high water years (W1 and combined) were significantly higher than those in normal water years (W2). Conclusion: In high water years when natural food shortage occurs, the Siberian Cranes can cope with the impact through increasing moving distance, enlarging home range and utilizing farmland more, to meet their energy need and improve their fitness. Nonetheless, the natural wetland is still the main foraging habitat and roosting habitat for Siberian Cranes wintering at Poyang Lake either in normal water years. In high water years, even the overall use of farmland in day time accounted for 50%, the natural wetland is still the main roosting habitat. The adaptive management of natural wetlands therefore should be strengthened in order to improve the function and resilience of wetlands as whole at Poyang Lake under different hydrological conditions and ensure the health and safety of 98% of global wintering population of Siberian Cranes.

Key words: Siberian Cranes, Poyang Lake, movement distance, home range, habitat use