Habitat use by the near-endangered dragonfly Aeshna mixta soneharai in reservoir ponds in Ueda, Nagano Prefecture, Japan

Abstract

The near-endangered dragonfly Aeshna mixta soneharai mainly inhabits artificial reservoir ponds and is a natural monument protected by the regulations of Ueda, Nagano Prefecture, Japan. The habitat use of this species was investigated on the Shioda Plain, where there are many reservoir ponds. The percentage of shoreline covered by emergent water plants was higher in ponds with the dragonfly than in those without the dragonfly. In the generalised linear model, forest and apple orchard areas around the ponds positively contributed to the occurrence of this dragonfly, in addition to shoreline emergent plants. A route census at an orchard showed that A. m. soneharai used the orchard as habitat. These results are consistent with the reproductive ecology of the species, which uses emergent water plants as spawning sites. A. m. soneharai use forest habitat for sub-adult maturation. Similar to forest, sub-adult A. m. soneharai are likely to use orchards. This study suggests that restoration near reservoir ponds would be effective for the conservation of A. m. soneharai. When it is difficult to restore forest around ponds, apple orchards with economic potential might serve as an alternative habitat.