Loss of biodiversity is a worldwide phenomenon and conservation of endemic species is becoming a pressing issue. However, species differ in life history characteristics, causing the best strategy for conservation to vary among species. Lucanus miwai is an endemic stag beetle of Taiwan, but the natural history and the conservation status of L. miwai have not been fully studied. Lucanus miwai adults live in forest-edge grassland habitats and are experiencing threats from anthropogenic exploitation. Additionally, climate change may threaten its long-term survival because of its specific habitat preference. Results from this study clearly indicate the need for more studies on the natural history of L. miwai and demonstrate that contemporary intensity of anthropogenic exploitation can have a negative effect on population size of this species. Future habitat loss because of global climate change, in addition, can be another major factor leading to population decline. Moreover, increasing demands on L. miwai because of population decline may lead to population extinction. In addition to protecting adult males from being collected, conservation strategies should also focus on discovering habitats utilized by individuals from different life stages, investigating the connectivity between populations, and maintaining the long-term availability of suitable habitats for L. miwai.