Abstract
There were consistencies among most relative density indices of sika deer Cervus nippon populations; however, population sizes were under-estimated in many areas in the Specified Wildlife Conservation and Management Plans (SWCMP). To start population management, accurate population censuses are particular important to determine the appropriate number for deer populations to be reduced to. Based on past experiences, we need to evaluate the degree to which population size has been underestimated by monitoring methods. We could estimate population size when the population is reduced via strong hunting pressure, because in such situations we know the harvest size and population growth rate. The development of appropriate monitoring methods, including large-scale monitoring and the establishment of nationwide monitoring programs such as the examination of traffic and railway accident information, is important.
