Le grand Corbeau Corvus corax en Biélorussie : Ecologie de la nidification

Data relating to the breeding biology of Raven Corvus corax in Belarus in 1976-1995 are summarised. In total, 188 nests were found and described. Most of the nests were situated on the edges of old sparse pine forest (35%) and in small forest remnants in cultivated areas (27.5%). Seven tree species were used as nest support, Scot's Pine Pinus sylvestris was the most common one (52% of tree nests). Power poles (17%) and triangulation towers (12%) were rather common nest supports. Raven started breeding from late February, mean egg- laying date being March the 17 th . The difference in clutch initiation dates between the north and south of the country was about 2 weeks. A significant correlation between latitude and egg-laying date was found. Clutch size varied from 3 to 7 eggs, it correlated significantly with egg-laying dates and nest height above the ground. Mean brood size was 2.5 young/active nest. Breeding success according to modified Mayfield's method was 38%. Brood size correlated significantly with nest height. Nest censuses on the sample plots yielded mean breeding density of 1 pair/10 km 2 . Variations in density were connected mainly with presence or absence of human food wastes, minimal density was recorded in abandoned areas near Chernobyl power station and maximal density near large dumps. In such areas of concentration where a lot of unterritorial individuals were observed, clutch size was significantly smaller than in areas with moderate and low density (3.5 and 4.5 eggs, respectively).