Ecological niches refer to the role and position of a species within an ecosystem, including how it meets its needs for food, shelter, reproduction, and interactions with other organisms. Each species has its own unique niche, which can be thought of as its ecological "job" or function within the ecosystem. The niche determines the species' interactions with other species and influences its survival and reproduction. This concept is crucial in understanding how different species coexist and thrive in a complex ecological community.