Scientific publications

The paper presents data on the current status of the Osprey and the White-tailed Sea Eagle populations in the northwestern part of the Vologda region and south-eastern Onego area. Field trips and studies at permanent plots done between 1988 and 2005 have demonstrated that the study area is inhabited by a uniform population of the White-tailed Sea Eagle, the main distinctive feature of which is the tendency to form compact settlements on the shores of large bodies of water in the forest zone. Its total abundance is ca. 100 pairs. About a third of the population (30–35 pairs) lives on the Rybinsk impoundment reservoir in the Darwin strict nature reserve, forming the largest source from which birds apparently dispersed to other large lakes of the region in the 1980s–1990s. Our estimate of the total Osprey population in the Vologda Lake District and south-eastern Onego area is 150–180 breeding pairs, of which 50–55 nest in the Darwin reserve and its buffer zone. Expeditions outside the area in question have shown that the population density of the species decreases towards all directions, their abundance being limited to occasional pairs. It is demonstrated that this source area with high abundance of the White-tailed Sea Eagle and the Osprey formed as the populations in the Darwin reserve increased in density in the 1950s–1970s. After that the species spread to lakes
and reservoirs of the Vologda Lake District and southeastern Onego area, where the natural habitats are similar.