Ecologically flexible endemics dominate Indo-Pacific bird communities

Reeve et al. (2016, Ecography, 39, 990-997) found that ecologically flexible endemics dominate Indo-Pacific bird communities. This negative relationship between local abundance and global range size contrasts strongly with the positive range size-abundance relationship “rule,” which would predict community dominance by globally widespread species. Theuerkauf et al. (2017, Journal of Biogeography, 44, 2161–2163) provide new data from New Caledonia which they claim invalidate our study. They find positive relationships between local abundance and local range size, which they attribute to endemic species having narrower habitat niches than globally widespread species. We reanalysed their data using global range sizes, corroborating the pattern we originally reported: negative relationships between local abundance and global range size, driven by a subset of adaptable endemic species. We stress the importance of being explicit about the scale of ecological mechanisms, and ensuring that the scale of analysis matches the scale of interpretation.