ИСТИНА

The social organization, reproductive behavior and ecology of the Eastern Great Reed Warbler were studied near Nahodka (Prymorskii Kray, Russian Far East) by means of individual marking and ringing in 2004 and 2005. The population occurs in the upland habitats and breeds in the small patches of reeds normally mixed with the tall herbaceous vegetation along the forest edges and irrigation channels. Most frequently the males vocalize sitting within canopies of the high trees surrounding the reed beds but the females place their nests predominantly in the reeds. The population has rather diffuse structure due to the low density of the birds and the wide dispersion of available habitats. The local clusters including the territories of 3-4 males were observed in most attractive sites. The rates of the polygynous males were 30% in 2004 (n=30) and 29% (n=31) in 2005. The majority of polygynous males have two breeding females on their territories. 33% of polygynous males in 2004 and 29% of polygynous males in 2005 have three females on their territories. 10% of all males in 2004 and 23% of all males in 2005 were bachelor. A number of males were observed to move widely throughout the breeding season. The data on the population dynamics, site tenacity and reproductive success are presented. We shall discussed the differences between the population structure of the Eastern Great Reed Warbler in the flooded and upland habitats as well as some differences between the Eastern, Western (A.arundinaceus) and Southern (A.stentoreus) Great Reed Warblers.