Figure 1 Asian openbill spatial occurrence and the observed niches of three populations in Niche A (a). We used all occurrence information as present data, the green triangle represents the original native population, the blue circle indicates the new northern population in China, and the red indicates the new southern population in the Malay Peninsula. The observed niche overlap (a) indicates that the new southern population niche (red ellipsoid) is a subset of the original native population (black ellipsoid), but the new northern population niche (blue ellipsoid) partially overlaps with the native niche and exceeds the native envelope.