Species rarity, defined as the extent to which a species is uncommon within a specific ecological community, is a key issue for ecological research and conservation efforts. As exemplified by several diversity indices, which typically quantify the average species rarity within a community, the significance of species rarity becomes evident. This paper aims to explore the distribution of species rarity, delving into higher-order moments beyond its first one, and analyzing their ecological implications for conservation efforts. Indeed, the consideration of variance, skewness, and kurtosis within the rarity distribution gain insights into its characteristics. Since the assessment of species rarity discerns from information derived from the species abundance vector, theoretical frameworks are developed to analyze the properties of species rarity estimators in a design-based framework. Overall, this study contributes to a deeper understanding of species rarity distributions and their implications for biodiversity assessment in ecological communities.