THE COMPARATIVE-ANALYSIS OF THE LEVELS OF PHYLOPATRY, POSTFLEDGING DISPERSION AND POPULATION-CHANGES IN WILLOW WARBLER (PHYLLOSCOPUS-TROCHILLUS) AND WOOD WARBLER (PHYLLOSCOPUS-SIBILATRIX) ON COURISH SPIT (THE BALTIC SEA)

Comparative analysis of natal and breeding phylopatry showed, that the return rates of willow warblers were significantly higher (adults 7,5 %, juveniles 7,5%, fledglings 7,0%), whereas wood warblers practically did not return either into their birth territory or into the former b reeding site (adults and fledglings 0,0%, juveniles 0,5%). Analysis of the data of ringing from other countries showed significant interpopu lation differences in the level of breeding phylopatry in wood warbler s (Table 2). The study of postfledging dispersal showed, that majority (70%) of wood warblers leave their birthplaces earlier than willow wa rblers (fig. 3). Unlike willow warblers, wood warblers fly mainly in t he south-western direction without stoppings (fig. 3, 4). As for the d ynamics of the studied local population of wood warblers, there is a s ignificant positive trend (fig. 2), The assumption is made, that the p opulation of wood warblers on Courish Spit, unlike that of willow warb lers, is renovated every year by immigration, not by native birds.