Urbanization has caused behavioral alterations in wildlife. Reduction in vigilance is the most widespread example in many species. This is probably due to decrease in natural predators in urban areas or habituation to humans. However, although animals usually alter their vigilance in response to the resources or environmental conditions that fluctuate temporally, seasonal differences in vigilance behavior have not been studied in urban populations. Seasonality of vigilance is predicted to be small in urban areas compared to rural areas because many studies showed resource stability in urban areas due to, for example, artificial feeding. Here, we compared seasonality of vigilance in the Eurasian red squirrel Sciurus vulgaris orientis between urban and rural in the Obihiro, Hokkaido. We measured flight initiation distance (FID) to human approach as an indicator of vigilance. We found that squirrels in rural areas lowered FID in autumn when many foods are required. However, no seasonal difference in FID was observed in urban squirrels, which is probably caused by persistent artificial feeding. If reduction of seasonality in vigilance is based on genetic adaptation, responses to future environmental changes, such as novel predator invasions, might be difficult