2025 Volume 65 Issue 2 Pages 153-162
From April 2021 to November 2022, we studied seasonal changes in the population size of the Japanese field mouse (Apodemus speciosus) in Ishinomaki (Miyagi Prefecture, northern Japan), focusing on its relationship with ground seed abundance. During the study period, mice were captured 115 times (36 individuals), with the capture frequency being particularly high during the summer. Juveniles were captured in July, September, October, and November, suggesting that these mice have two breeding seasons in Ishinomaki, similar to that of populations elsewhere in Honshu. Seed abundance was high in the fall, suggesting that food conditions were favorable for the mice during this season. Although seed abundance had no significant correlations with the number of mice captured in a month, it did have a significant negative correlation with the number of mice captured in the following month to at least two months later. The time lag between food conditions and capture numbers could be due to the period until the newborn mice were dispersed to the study site and/or until their foraging behavior changed in response to the ground seed abundance.
