Habitat Quality, Conservation Gaps, and Environmental Suitability of Siberian Cranes (Leucogeranus leucogeranus) in the Erlongtao River Basin, Songnen Plain

Wetland degradation induced by climate change and human disturbance poses severe threats to migratory waterbirds, particularly the critically endangered Siberian crane (Leucogeranus leucogeranus). The Erlongtao River Basin, a key stopover wetland complex on the Songnen Plain, exhibits prominent mismatches between general waterbird habitat quality and species-specific habitat suitability, together with widespread conservation gaps. In this study, line-transect and point-sampling field surveys were conducted during spring and autumn migration (2020–2024). The eight phases of land use datasets (1990–2023), the InVEST Habitat Quality module, and the MaxEnt habitat suitability model were used to quantify 33-year spatiotemporal dynamics of habitat quality and contributions from land use transitions, map spatial patterns of Siberian crane suitable habitats, and identify conservation gaps within and outside two national nature reserves. Wetland shrinkage and swamp fragmentation degraded regional foraging and habitat conditions for waterbirds. Transitions from unused and construction land to water bodies, shallows, and swamps increased habitat quality, whereas cropland expansion and soil salinization drove habitat degradation. In 2020, high-, moderate, and low-suitability habitats for Siberian cranes occupied merely 0.18%, 1.37%, and 3.55% of the total watershed area, respectively. Dry farmland constituted 47.97% of high-suitability habitats, 44% of which belonged to the poor-quality land cover class grade. Meanwhile, 66% of highly suitable habitats and 68% of moderate-suitability habitats occurred outside protected area boundaries. Targeted restoration of water body and swamp patches with high habitat quality contributions is needed to maintain Siberian crane populations. This work offers quantitative conservation strategies for this flagship species and provides theoretical support for spatial planning of the proposed Songnen Crane National Park.