Study on habitat suitability and ecological network of rare cranes in Poyang Lake National Nature Reserve

The Poyang Lake National Nature Reserve (PLNNR) is the most important reserve for wintering migratory birds in the Poyang Lake basin. The analysis of the spatial distribution of rare crane habitats and their response mechanisms to environmental variables is crucial for the conservation and restoration of both species and habitats. This study focuses on the rare crane species in the PLNNR, including Siberian Cranes (Grus leucogeranus), Hooded Cranes (Grus monacha), White-naped Cranes (Grus vipio) and Common Cranes (Grus grus). Based on occurrence data and environmental variables, the Maximum Entropy (Maxent) model was used to analyze the habitat suitability of the four crane species and to discuss their response mechanisms to key environmental variables. In addition, an ecological network was constructed for the four crane species using circuit theory and the Minimum Cumulative Resistance (MCR) model. The research results indicated that the highly suitable habitats for the four crane species were distributed along the edges of lake wetlands, with an area ranging from 63.97 to 128.21 km², accounting for 15.31 to 30.69 %. The unsuitable areas were located in Wucheng town and along the waterways, with each area exceeding 25 %. Land use types, including reed beach, mudflat, waters, and cultivated land, were the main factors influencing crane habitat, with a contribution rate ranging from 15.9 to 36.3 %. In addition, the significant environmental variables varied among crane species. For the Siberian Crane, key factors included distance from grassland, aspect of slope, and distance from water. The Hooded Crane was primarily influenced by distance from water. The White-naped Crane was significantly affected by distance from grassland, cultivated land, and waterways. For the Common Crane, distance from water and construction land were the main influencing factors. Ecological networks were constructed for the four crane species and the PLNNR. The ecological network of the PLNNR consisted of 9 ecological sources, 13 ecological corridors, and 27 ecological nodes. Overall, the construction of the ecological network in the PLNNR was superior to that of individual crane species.