Hobby collections as a threat to rare species: the example of stag beetles in Japan

The higher value of rare items in collections is a phenomenon also found in wildlife based collections, such as insects. If rarer species are more valued and therefore more sought after, they could be disproportionately harvested in the wild, which could render them even rarer, thus even more valuable, and even more exploited. This could drive rare species towards extinction. We focus here on the hobby of collecting stagbeetles, to ascertain if the market value of these items is driven by rarity and if, consequently, these species are vulnerable to rrity-driven overexploitation. Stag bettle collections fuel a large and lucrative market in Japan, involving more than 700 species from all over the world, with over 15 million specimens imported a year. Some particularly valuable species fetch more than US$ 5000 a piece. We assessed the importance of species rarity as an acquisition criterion in this market using two methods: an Internet online experiement and through examining the volumes sold and prices paid by collectors. We discovered that species rarity is one of the main choice criteria for acquisition by collectors: rare stag bettles are valued more than the common species and, consequently, rare stag beetle species are vulnerable to overexploitation in this market. Because of the sheer size of the market, and the pervasive nature of this rarity paradox, the attraction to rarity equates to a potential extinction threat for many rare stag beetles species.