Movements of radio-tagged Buzzards Buteo buteo in early life



Radio-tags were used to track 146 Buzzards Buteo buteo during 1990–1996. Each bird was tracked for up to 4 years; of 74 Buzzards tagged since 1992, 72% were monitored for more than 3 years. Among the 87 Buzzards tracked for more than 1 year, 46% settled after one dispersal movement, 37% dispersed and then changed their ranges, 17% did not disperse and one Buzzard alternated between a summer and a winter range. Natal dispersal occurred in two waves, one in the first autumn and the second in the following spring. Initial dispersal distances in the autumn were significantly greater than those in the spring. For 73 Buzzards that dispersed in their first autumn, 96% settled within 100 km of their natal nest, and their distances were similar to 76 records from ringing. After their second spring. Buzzards rarely changed ranges and were significantly more often to the east than the west, especially those that had dispersed more than 20 km. Buzzards that had dispersed farthest were most likely to be detected returning towards their natal area each spring and returned earlier as they got older. However, none was detected returning once it had started to breed. Nine early breeders were significantly farther from their natal nests than 44 nonbreeders.