Big cities like Tokyo produce enormous amounts of raw garbage. In Tokyo, as much as 4 million tons of raw garbage is created annually. This huge amount of raw garbage seems to have attracted and contributed to the population growth of crows. The nature of the crow problem lies not in the mere increase in the crows' number, but in the increase in the number of residents.
The crows, which have been overbreeding, are smart, and are causing various problems because of their intelligence. In cities, troubles between crows and people do not arise from the crows' behavior as birds. They seem to arise from the crows' lives as they intersect with the lives of humans.
The first step to solving these problems is to gain an understanding of the crows' behavior in cities. However, it used to be very difficult to study such behaviors.
A remarkable new method of tracking crows has been jointly developed in conjunction with Prof. Kiyoshi Itao (General Editor of Nature Interface). In this method, crows are tracked by PHS's, or "Personal Handyphone System." This article discusses the problems crows are causing in cities, and describes the PHS method used for tracking crows.