5:15 PM - 7:15 PM
[MIS12-P11] Time-lapse observations of winter stoneflies’ behavior on snowpack using a 360-degree camera
Keywords:winter stonefly, 360-degree camera, migration
Winter stoneflies are wingless species of Plecoptera insects and are actively walking on snowpack surfaces in Japan during winter. Their nymphs stay under leaf litter in streams in summer and fall and emerge on snow surfaces in winter or early spring. Adults of the stoneflies migrate upstream by walking, using the sun as a compass to decide their walking direction. However, diurnal and seasonal changes in their activity and the effect of weather conditions on their behavior have been little known. In this study, we aimed to observe the behavior of winter stoneflies on snowpack surfaces using a 360-degree time-lapse camera to understand their life cycles.
The fieldwork was carried out in March and April of 2024 in Mt. Gassan in Yamagata prefecture in Japan. A 360-degree camera was installed on the snowpack near stream and took photographs of all snow surface and sky every two second for 48 hours. Stonefly specimens found on the snow surface were collected. All individuals collected in March (12) were Eocapnia sp.(Es1). In contrast, seven out of nine individuals collected in April were Eocapnia sp.(Es1), and other two were Eocapnia shigensis. All females collected in in April (10) were mature, while all females collected in March were not mature. These results indicate that the maturation of the winter stoneflies proceeded from March to April. The 360-degree photographs revealed that the number of stoneflies walking on the snowpack reached a maximum between 9:00 and 9:30 on a sunny day in March, while it reached a maximum between 5:30 and 6:00 on a sunny day in April. The direction of stonefly migration changed from March to April: they moved away from the stream in March but no significant trend in April. These results suggest that the activities of the winter stoneflies changed significantly from March to April; they emerged and actively migrated to upstream in March while settled down for probably oviposition in April.
The fieldwork was carried out in March and April of 2024 in Mt. Gassan in Yamagata prefecture in Japan. A 360-degree camera was installed on the snowpack near stream and took photographs of all snow surface and sky every two second for 48 hours. Stonefly specimens found on the snow surface were collected. All individuals collected in March (12) were Eocapnia sp.(Es1). In contrast, seven out of nine individuals collected in April were Eocapnia sp.(Es1), and other two were Eocapnia shigensis. All females collected in in April (10) were mature, while all females collected in March were not mature. These results indicate that the maturation of the winter stoneflies proceeded from March to April. The 360-degree photographs revealed that the number of stoneflies walking on the snowpack reached a maximum between 9:00 and 9:30 on a sunny day in March, while it reached a maximum between 5:30 and 6:00 on a sunny day in April. The direction of stonefly migration changed from March to April: they moved away from the stream in March but no significant trend in April. These results suggest that the activities of the winter stoneflies changed significantly from March to April; they emerged and actively migrated to upstream in March while settled down for probably oviposition in April.