Niche Segregation Between Black‐Necked Crane and Common Crane in Human‐Modified Landscape, Huize Black‐Necked Crane National Nature Reserve, Yunnan Province, Southwestern China

ABSTRACT Agricultural expansion has created mosaic landscapes that are crucial for migratory birds, yet these anthropogenic habitats intensify challenges like interspecific competition. Understanding how sympatric species coexist through nutritional niche adjustments is a critical knowledge gap for conservation. We studied the wintering Black‐necked Crane ( Grus nigricollis ) and Common Crane ( G. grus ) in an agro‐wetland system in southwest China, where seasonal resource decline is expected to drive niche differentiation. Using fecal DNA metabarcoding, we reconstructed and compared their plant‐based diets throughout the winter. The two species employed divergent foraging strategies. Black‐necked Cranes were conservative generalists, maintaining high dietary richness and consistently relying on a core set of natural food sources (e.g., Poaceae, Solanaceae, and Cyperaceae), using crops only as supplements. Conversely, Common Cranes were dynamic specialists, exhibiting a complete turnover of preferred foods and opportunistically concentrating on the most energy‐dense crops available in each period (e.g., Fagopyrum esculentum , Helianthus annuus ). This strategic divergence resulted in a continuous decrease in NO, from high initial similarity to complete partitioning by the pre‐migration stage, while ND increased correspondingly, reflecting progressive trophic niche separation. We conclude that this dynamic niche partitioning, driven by distinct responses to seasonal resource availability, is the primary mechanism facilitating the coexistence of these two large congeneric species. Our findings reveal profound dietary plasticity and offer a scientific basis for managing anthropogenic landscapes to support multispecies conservation goals.