Abstract: Intensified global climate change and anthropogenic disturbances have triggered widespread degradation of avian habitats worldwide, posing severe threats to the survival and population stability of rare and endangered bird species. In this context, the scientific identification and targeted conservation of critical habitats have become crucial measures for improving the effectiveness of biodiversity conservation and species protection. The Saunders′s Gull (Saundersilarus saundersi) is a rare and vulnerable bird species listed as Class I nationally protected in China. It is characterized by a strong dependence on coastal wetland habitats and a high sensitivity to environmental changes and human interference. Taking the population of Saunders′s Gull in the Yellow River Estuary National Park Candidate Area as the research subject, this study systematically integrated 227 valid field distribution points, and selected 8 major categories of environmental variables (including terrain, climate, human activities and food resources). The widely applied and robust Maximum Entropy (MaxEnt) model was employed to quantitatively simulate and project the species′ current and future potential suitable habitats. Based on the spatial distribution pattern of highly suitable habitats, key priority conservation areas were further delineated. In addition, a systematic conservation gap analysis was conducted to comprehensively evaluate the conservation effectiveness and existing deficiencies of the current regional protected area system. The results revealed the following: (1) The potential suitable habitats of Saunders′s Gull exhibited a highly concentrated spatial distribution. Under current climatic conditions, the total suitable habitat area reached 236.42 km², of which highly suitable habitat covered only 24.02 km², primarily distributed in the coastal tidal-flat wetlands of the Yellow River Delta. Under two typical future climate scenarios, the overall suitable habitat area showed a significant declining trend. Under the SSP5-8.5 high-emission scenario, the habitat loss rate reached 15.24%, and the spatial centroid of the habitat shifted markedly toward the northwest. (2) Environmental factor analysis indicated that distance to construction land was the dominant limiting factor affecting the habitat selection of Saunders′s Gull, with a contribution rate of 33.1%, followed by regional food supply conditions, which contributed 8.1%. (3) The conservation gap assessment demonstrated that the existing protected area system cannot provide effective shelter for Saunders′s Gull habitats, with an overall habitat protection rate of only 40.4%. The average conservation gap rate within the priority conservation areas exceeded 59%, indicating that the core habitats and survival areas of Saunders′s Gull were not comprehensively covered by the current core protected areas. This study elucidates the spatial distribution characteristics, driving factors, and conservation gaps of Saunders′s Gull habitats in the Yellow River Estuary National Park Candidate Area, and provides scientific evidence and practical guidance for refined and adaptive habitat management of wetland birds as well as for the optimization and adjustment of the regional protected area layout.