Abstract: Nest site selection of birds during reproductive period is affected by many factors. Many kinds of passerines nest on the tree. Due to the lack of natural woodland in open coastal areas, the artificially planted seawall forests could provide essential nesting grounds for many passerine birds. In this study, nest distribution and nest site selection of two dominant breeding species (Eophona migratoria and Dicrurus macrocercus) were studied in seawall forest near Jiangsu Dafeng Milu National Nature Reserve from April to August 2018. A total of 127 nests belonging to 10 species were recorded, with the height of the most nests being above 5 m. The results of principal component analysis (PCA) showed that the main factors affecting nest site selection of E. migratoria were the traits of nested tree and shrub, and the secondary affecting factors were nest location, number of tree and safety (the cumulative contribution rate of the first five principal components was 71.9%). Similarly, traits of nest tree and shrub were the main factors affecting the nest selection of D. macrocercus, while nest direction and number of trees were the secondary factors (the cumulative contribution rate of the first five principal components was 78.0%). With the niche differentiation of nest sites, significant differences were detected in nest direction factor (U_test,Z=-3.013,P<0.01), nest height factor (U_test, Z=-6.718,P<0.01), nest location factor (U_test, Z=-5.402, P<0.01), and concealment factor (U_test,Z=-4.081, P<0.01). The niche overlap values of the two species were large (from 0.500 to 0.998) in most factors of nest site selection, indicating strong interspecific competition between them.

Key words: root-zone soil, agricultural carpet, straw mat, mulching, apple, nitrate metabolizing.