Yasushi Kiyokawa, ryoko koizumi, Ryoko Yamada, Masayuki Hijikata, Goro Kimura, Kazuyuki D. Tanaka, Yukari Takeuchi, Tsutomu Tanikawa

Brown rats (Rattus norvegicus) and roof rats (Rattus rattus) are among the most common mammals worldwide. Little is known about the effects of season on rat population size, which is important for understanding rat ecology and/or performing effective rat control campaigns. Tsukiji Market was a metropolitan central wholesale market in Tokyo and was located within 1 km from one of the biggest downtown areas. To control rats in the market, a pest management professional exclusively conducted annual campaigns at two fixed time points for many years. In addition, the pest management professional successfully confined all rats to the market and exterminated them when the market was closed and demolished. We analyzed these records to assess whether this rat population in Tokyo showed seasonal fluctuation and to provide information regarding rat management in a facility located in a downtown area. Multiple regression analyses revealed that trap success was affected by human activities (total trading volume and number of foreign tourists in Japan), but not by the month the campaign was performed. These results suggest that the rat population in this market did not show seasonal fluctuation. The results also suggest the importance of the effect of human activities on the ecological dynamics of rats in urban cities. We also described details of the campaigns performed as the market prepared to close to provide information regarding how to control rats in facilities in a downtown area.