Bird Species Diversity and Spatio-Temporal Variation in the Sihong Hongze Lake Wetland National Nature Reserve in Eastern China

As an important hub on the East Asian-Australian Flyway (EAAF), Hongze Lake is an important migratory stopover and wintering site for hundreds of thousands of birds. However, research on bird community diversity in this area is still lacking. We conducted a bird survey from July 2020 to June 2021 using the line transect method on the terrestrial habitat, as well as the fixed-point method in the lake wetland at the Sihong Hongze Lake Wetland National Nature Reserve located in northwestern Hongze Lake, and analyzed the temporal-spatial variation in the bird community. The results showed that a total of 170432 detections of 215 bird species belonging to 18 orders and 55 families were recorded. In terms of species composition, the proportion of terrestrial birds was relatively high, followed by waterfowl richness, with high numbers of Anatidae species and shorebirds. For bird species abundance, waterfowl had the highest abundance of common coot (Fulica atra), belonging to the Rallidae family, followed by Anatidae and Ardeidae species. The abundance of shorebirds was extremely low, and that of non-waterfowl was also low. In terms of temporal patterns, the number of bird species and richness index were higher in spring and autumn but lower in winter and summer. The bird abundance was the highest in winter, and the remaining three seasons were similar in terms of bird abundance. The diversity index and evenness index were higher in spring, summer and autumn, and lowest in winter. For the spatial pattern, the open water in the western part of the reserve included the most densely distributed areas for birds, and the number of bird species and their abundance were both the highest in that part. There were significant differences in the bird community structures among the four habitats. The species number and richness index of birds in the reed habitat were the highest, and the bird abundance was also high, but the diversity index and evenness index were low. Although the bird abundance in the lake habitat was much higher than in the other habitats, the diversity index, evenness index and richness index were the lowest. The numbers of bird species and individuals in tourist attraction land and farmland were low, but the diversity index, evenness index and richness index were high. Our results reveal the spatial and temporal patterns of bird species diversity and abundance in Sihong Hongze Lake Wetland National Nature Reserve, and reflect the effects of different habitat types on bird diversity.