Abstract
The jungle crow Corvus macrorhynchos and the carrion crow C. corone in urban and residential areas often damage plastic garbage bags, by ripping open the plastic, and scatter the contents. Their foraging behavior on garbage (trash) bags causes littered and stinking streets, and decreases the efficiency of garbage collectors. To solve the problem, we need to determine the best way to protect the garbage from crows while the bags wait on the street for collection. We obtained three findings after researching 2000 garbage bags during the winter of 2015–2016 in Hakodate City. First, the garbage bags placed in front of apartment houses were ripped open more frequently than those placed in front of detached houses. This may be because people living in detached houses are personally responsible for cleaning up their own litter when their garbage is scavenged by crows, so they pay more attention to the manner in which they dispose of their garbage. Second, garbage bags were ripped open by crows more frequently when the bags were either unprotected or when covered only by a nylon net or a blue plastic sheet. Those placed in various types of containers, such as a steel mesh basket box or a plastic basket box, were less frequently opened by crows. Third, garbage bags placed in steel mesh basket boxes with additional protection, such as when mesh sides were covered by a wooden or an acrylic board, were less frequently ripped open by crows than those placed in steel mesh basket boxes without additional protection. These three findings suggest that to solve the problem, (1) people living in apartment houses should pay attention to the manner in which they dispose of their garbage, (2) a container with lid should be used instead of a nylon net or a plastic sheet, and (3) when using a container with mesh sides, the mesh sides should be covered with a wooden or an acrylic board to prohibit access by crows.
