[pp.41-50]

Environmental Factors Influencing the Roosting Sites of Carrion Crows (Corvus corone orientalis Eversmann) in the Southe

Teruo ARASE and Taizo UCHIDA （Shinshu University / Kyushu Sangyo University）

Abstract:
Carrion crows (Corvus corone orientalis Eversmann) cause severe agricultural damage in Nagano Prefecture. The purpose of our work was to find ways to co-exist with crows and prevent agricultural damage. In this study, we identified the location and distribution of roosting sites of carrion crows during fall and winter in the southern part of Nagano Prefecture, in 2005, 2006, and 2007. The topography and vegetation of the roosting sites were investigated. Human population, agricultural area, and forest area in the home range of the crows were considered to be environmental factors. Using data available from the municipalities, these environmental factors were compared with the flock size of roosting crows. We observed 14 roosting sites in the research area which were separated by distances of 15– 20 km. Topographically, the roosting sites were generally located on the slopes of river terraces. The vegetation of the roosting sites was categorized into four types: three forest types and an urban site without vegetation. Multiple regression analysis was used to determine the influences of the environment factors on the flock size. In the result, human population and agricultural area had positive coefficients, while forest area had a negative one.

Key Word:
Corvus corone orientalis, roosting site, topography, vegetation, home range area

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