The niche has been central to ecology for most of the discipline’s history, yet there have been few attempts by philosophers to work out the ontology of the niche. A challenge is that there is a plurality of seemingly inconsistent definitions of the niche in ecology. This paper characterizes the population-level ecological niche by distinguishing among niche concepts, niche models, and the niche as a phenomenon. I argue that 'niche concepts' should be interpreted as theoretical frameworks or modelling strategies. I (...) also argue that there is a unified niche phenomenon underlying the seemingly heterogeneous models and definitions. The plurality of niche concepts in ecology should be seen as an expected consequence of the nature of modelling complex systems. (shrink)