Crows Problems in Sapporo Area

Abstract

　Crows in urban and residential areas have caused friction and problems in Sapporo, as in other urban areas in and out of Japan (Ministry of Environment, 2001; Vuorisalo et al., 2003; Gorenzel et al., 2002). The problems include garbage depots messed up by crows, attacks on passers-by particularly near nests, and damage to fruits and crops. Crows are often regarded as a nuisance and arouse feelings of fear or resentment often based on false assumptions among some citizens. This results in frequent claims from the citizens that the city must eradicate as many crows as possible. However, the management and control of crow populations, if necessary, should be based on correct data and observation of their ecology, behavior, distribution and abundance. These data may also be used to improvise measures to drive crows away effectively from undesirable areas. This paper describes the status of two common crow species, Corvus corone and C. macrorhyncus, in the Sapporo area in the winter of 2002 and 2003. The results of a roost site survey were compared with some of the results obtained in between 1991 and 2001, which proved that the crow population stayed fairly constant between those years. Roadside censuses revealed that the temporal and spatial distributions of these two species varied considerably from late autumn to winter. Garbage depot surveys illustrated clearly that protecting garbage depots was an effective method for curbing the number of crows in the neighborhood. Municipal and residents’ efforts are also described, which are aimed at finding better ways of coexisting with crows rather than haphazardly eliminating them. Though still at an early stage, the city’s project to understand the ecology of crows as wild bird species is expected to be helpful in terms of both raising citizens’ awareness of the advantages of peaceful coexistence with crows and devising methods to curb the numbers in undesirable areas.