Colias palaeno sugitanii habitat at Midagahara, Tateyama Mountains

Abstract

Colias palaeno sugitanii is an alpine butterfly that inhabits the alpine to subalpine zones in the central mountains of the Japanese archipelago. Global warming has led to a decrease in its habitat and it was designated a near-threatened species in the 2019 Ministry of the Environment Red List. At present, however, there is insufficient basic ecological research on the habitats and life cycle of this species. To conserve Colias palaeno sugitanii, we conducted a survey in the highland moor at Midagahara (elevation 1600~2100 m) in the Tateyama Mountains, which is one of its main habitats. We recorded 529 adults between July 17 and August 18, 2019. This species was recorded from grassland over 1700 m and was not found in valleys or forests in the surveyed area. To evaluate factors determining the occurrence of this species in grassland, logistic regression analysis was conducted using environmental and topographical features. Site slope had a positive effect on its occurrence, while the presence of a pond had a negative effect. These results suggest that adults of this species tend to use well-drained grassland with relatively high slopes. We also investigated the species composition, morphological features, and habitat of the food and host plants used by Colias palaeno sugitanii. The results suggest that future environmental changes might lead to further declines in its population.