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Raumnutzung und Verhalten von Wespenbussarden (Pernis apivorus) während der Jungenaufzucht und zu Beginn des Wegzuges – eine telemetrische Untersuchung
Home range and behaviour of Honey Buzzard (Pernis apivorus) during brood-rearing and at the begin of autumn migration - a radio telemetry study 2 male and 2 female Honey Buzzards were radio-tracked in 3 study areas in the period 1993-1995 in Schleswig-Holstein. All birds produced fledglings. Home ranges of females were larger (4,350 resp. 4,500 ha) than those of males (1,700 resp. 2,200 ha). The tracked birds preferred forests, agricultural areas with hedgebanks, and bogs where they searched for prey mainly from perches. Identified prey items were 1 bumblebee and 64 wasp nests (Table 3). This sample is, however, not considered to be representative. Normally, each bird went hunting on its own. Sometimes, however, a bird was followed by its partner. 3 times a male seems to have partaken at its female’s wasp nests. Both sexes supplied the nestlings with food, but females retained from this until the young were nearly 3 resp. 4 weeks old. A male which fed 2 nestlings spent progressively 35 to 58 % of observation time hunting. The males defended territories of not less than 640 and 380 ha, respectively, which they marked by quivering flights and surveyed them during extended gliding flights. One male spent 6-7 %, the other (depending on weather conditions) 14-23 % of the observation time on such surveillance flights. Home ranges of neighbouring pairs overlapped widely. Even territory boundaries were often trespassed. Females did not show territorial behaviour. This may have allowed them to extend their home ranges much further than males which tended to keep to their territories. The adult breeding birds started autumn migration alone, without their partners, when the fledglings had reached an age of at least 53 days. It was the female in 1993 and the male in 1995 which was the first to migrate. Their resp. partners remained to feed the young 3 or more days. On their day of departure the males migrated ca. 133 km SSE resp. ca. 210 km SW. Length and direction of migration were strongly influenced by weather conditions.