In the light of the white-tailed eagle (Haliaeetus albicilla) population growth in many European countries we tried to find out how the osprey (Pandion haliaetus), which inhabits mainly the upland bogs of Northern Belarus and have similar to white-tailed eagle ecological niche, behave. Nesting biotopes, nesting trees, the architectonics of nests, as well as food spectra of the osprey and the white-tailed eagle in the Vitebsk region of Belarus were compared in order to identify the principal parameters of their ecological niches. Breeding territories were searched by using the circular plot census method modified by Dombrovski. Descriptions of nest site positions were done using the forest stand maps of local forest management divisions. Forest blocks and particular stands where the nests were situated or suspected to be situated were identified from the maps, and available state survey stand features were used. Diet was studied by standard methods. In the result of Morishita-Horn index calculation, it was shown that the competition between ospreys and White-tailed Eagles might occur during feeding on fish. The other parameters are not overlapped. Species solve this problem by preying on different fish size classes.