Status and breeding performance of the Osprey Pandion haliaetus in northern Byelorussia

Abstract

Distributional and breeding data on the Osprey Pandion haliaetus were collected in northern Byelorussia during 1976-90. The population size was estimated at 100-120 pairs ; proved nesting records from other parts of the country are lacking for the last 8 years. Small pines on peat bogs were used for breeding by 90% of the Ospreys. The main part of the population used natural nest sites; only 7% of the nests were built on artificial platforms. The mean clutch size was 2.82 and the mean size of successful broods was 2.06. The brood size per active nest was 1 .59 and per occupied nest 1.29. Addled eggs and fallen nests were the main reasons for reduced productivity . Early clutches produced more young in the successful nests. It seems that the population size has remained stable during recent years.