Rarity and shifts in occurrence of endangered butterflies in South Korea

Endangered species are often the focus of public attention, partly because of their vulnerability to environmental changes, such as climate and land use change, and subsequently being at high risk of extinctions. Hence, red lists of endangered species play anessential in nature conservation. Although several endangered butterfly species have been previously listed as endangered species by government and/or individuals in South Korea, these red listsrarely include reliable quantitative population data. This has led to endless and unproductive debates on the selection of endangered species. Following Korean butterfly atlases, we assessed the population status of Korean endangered butterfly species whose distributions have been previously published. We hypothesized that these endangered species are rare and are decreasing in occurrence. We found that the decrease in occurrence is more important in determining endanger status than rarity. Using values of rarity and shifts in species occurrence, we selected endangered species from the previously published endangered species. Only eight species of 20 previous endangered species were defined as endangered by this semi-quantitative classification. This finding suggests that the subjective determination based on expert's perception would define more species as endangered compared to the quantitative determination based on population data.Article信州大学農学部紀要 50（1-2）: 37-42(2014)departmental bulletin pape