Influence of the disturbance factor and investigators press on the nest ruin of passerine birds (a case study of the Red-backed Shrike). - N.P. Knysh. - Berkut. 3 (1). 1994. - P. 38-39.
The study was curried out in the forest-steppe part of Sumy region in 1973-1993. Two questions were studied: the share of ruined nests depending on the beginning time of their visiting and its dependence on the frequency of visits. From 734 total nests under control 374 have been perished (51,0 %). Visiting of nests during the early stages of breeding mostly dooms them to perish. Birds leave the nests, or they are ruined by raptors. 1-3 first visits are critical for the existing the nest. In two cases the throwing of eggs out of the nest by female after its investigation was observed. By the repeated breeding the clutch size decreases on the average by 1 egg. The nest visiting leads on the whole to the decreasing of the breeding success. [Russian].
Key words: Red-backed Shrike, Lanius collurio, disturbance faktor, breeding success.