Only Urban Cicadas Found to Sing at Night: Japanese Team

Tokyo, July 22 (Jiji Press)–A Japanese research team has found that some cicada species in urban areas called at night, while few such calls were recorded in greener areas without street lights. This suggests that some cicada species may be changing their activity times due to nighttime lighting and rising temperatures associated with the expansion of concrete structures, the research team led by Tokyo Metropolitan University said. The findings from long-term observations of various cicada species using autonomous recording units appeared in Ecological Research, an English-language academic journal published by the Ecological Society of Japan in April. Between late June and late August 2024, the team set up autonomous recording units to capture cicada sounds around the clock at Tokyo Metropolitan University’s Minami-Osawa campus in Tokyo’s Hachioji, Tamagawa University’s campus in the Japanese capital’s Machida and Azabu University’s campus in Sagamihara, Kanagawa Prefecture, south of Tokyo. Such devices were also installed at three locations in Machida’s green conservation areas. The recordings were analyzed to determine how frequently the cicadas called each hour. Sounds made by six cicada species were confirmed. “Aburazemi,” or Graptopsaltria nigrofuscata, and “niiniizemi,” or Platypleura kaempferi, living in urban areas were found to call both during the day and at night, while those in greener areas were not heard calling at night. On the other hand, “minminzemi” (Hyalessa maculaticollis), “higurashi” (Tanna japonensis,) “kumazemi’ (Cryptotympana facialis) and “tsukutsukuboshi’ (Meimuna opalifera) were quiet throughout the night in both urban and green areas. The findings suggest that the cicadas’ sensitivity to urbanization varied from species to species, the team said. “We hope people will learn about the impact of human activities on ecosystems through cicadas, which are familiar creatures to us,” Takeshi Osawa, an associate professor at Tokyo Metropolitan University, said. END [Copyright The Jiji Press, Ltd.]