Nest Site Comparisons between the Carrion Crow Corvus corone and Jungle Crow Corvus macrorhynchos in Takatsuki City

Abstract

During the breeding season, Carrion Crows Corvus corone and Jungle Crows Corvus macrorhynchos widely overlap each other in suitable habitats. During the 1991 breeding season their nest site characteristics were studied in Takatsuki City, Osaka, Japan. The study area comprised urban areas, adjacent farmland and woodland. I found that 52% of Carrion Crow nests were built in evergreen trees, 25% were in deciduous trees and 23% were placed on artificial structures. In many cases, nests were built in sparsely wooded areas. Most Jungle Crow nests were located in evergreen trees (92%), 3% were in deciduous trees and just 5% were built on artificial structures, and almost all nests were found in large areas of woodland. The average distance between a nest and the edge of the forest was 20.3m for Carrion Crows and 113.7m in the case of the Jungle Crow. As a general rule, it was more difficult to discover the nests of the Jungle Crow than the nest of the Carrion Crow. The ratio of cropland in the area around the nest site (r<150m), was larger in the Carrion Crow than in the Jungle Crow. The ratio of woodland was extremely small in the Carrion Crow and was variable in the Jungle Crow. Almost all of the Jungle Crow nests (81%) in evergreen trees were in areas of extensive woodland. In contrast to this, 85% of Carrion Crow nests were found in another combination of micro-habitat, including deciduous trees, artificial structures, medium or small areas of woodland, or small groves of trees. The feeding behaviour and the preference for nest site concealment differed considerably between the two species. These differences may induce nest site segregation.