Mass evacuation of beach arthropods during stormy weather

Extreme weather events such as storms can generate intense wave action and strongly affect coastal ecosystems. Animals may avoid such disturbance by moving to refuges, thereby mitigating the effects of extreme weather. However, because extreme weather events are infrequent and unpredictable, such behavioral responses are difficult to study systematically, leaving evidence largely limited to opportunistic observations and anecdotal reports. Beach arthropods are highly mobile and inhabit environments regularly disturbed by waves and tides, making them a useful system for examining behavioral responses to extreme weather. We monitored landward movements of arthropods on an armored shingle beach in eastern Hokkaido, Japan (43.12°N, 144.50°E), from 2023 to 2025. Pitfall traps were placed above a seawall separating the beach from adjacent terrestrial habitat to quantify arthropods moving landward beyond the beach habitat. Landward captures increased repeatedly during periods of high wind speed, but responses differed among taxa. Talitrid amphipods showed the strongest increase with wind speed and declined on the windiest day recorded during the survey period, while spiders, earwigs, and sea roaches showed similar patterns. By contrast, seaweed flies, rove beetles, and ants showed no clear wind-related changes. These results suggest that some beach arthropods can respond behaviorally to extreme weather events by temporarily moving away from their normally occupied beach habitats, although such responses may have limits under particularly severe events. These findings highlight behavioral flexibility as a potentially important component of how animals cope with extreme weather.