VOSKAMP P (2000) Population biology and landscape use of the Honey Buzzard Pernis apivorus in Salland. LIMOSA 73 (2): 67-76.

The population biology of Honey Buzzards was studied in two adjacent study areas in Salland (central Netherlands) of 145 km2 (1994-1998, southern part) and 215 km2 (1996 and 1998, northern part) respectively. Scattered woodland covers 14% of the area, the rest is farmland (Fig. 1). Much time was spent in observing and describing territorial birds (plumage characteristics), resulting in location of home ranges and nests. Nests were checked by climbing during egg and/or nestling stage. Foraging flights were mapped from high observation points by following food-carrying adults (24 out of 35 flights could be used in this analysis, based on 124 observation hours).

During 1994-98 the population remained stable at 16 territorial pairs, all territories being occupied year after year (Fig. 2), even in years with poor breeding results. Spacing of territories was fairly constant. considering the distribution and availability of wood land (2-3 km between centres of territories in the southern study area, average density 0.11 territory/ 100 ha). At one site, however, three nests were situated within a stretch of a single kilometer. In 1996 in each of these three nests eggs were laid. Fourteen out of 17 nests built by Honey Buzzards were situated in firs and spruces (Tab. 1). This preference can probably be explained by the concealment such trees offer against raiding Goshawks. Only two pairs used the same nest twice (2 x) or three times (1 x) . Within the same territory, nests were up to 2.5 km apart in successive years. Two intensively studied pairs showed minimum home ranges of 1550 and 1700 ha for males and 2500 and 2600 ha for females (Fig. 3). Median distance of foraging flights during the nestling stage averaged 1.9 km in males and 3.2 km in females (Fig. 4).

On average, fledgelings were raised in 24% of the territories (6-38%; Fig. 2). The number of fledglings per successful nest averaged 1.71 (14x2, 5x1). Calculated for the southern study area (1994-1998), on average 0.41 nestlings per pair were raised . Although some failed breeding attempts were recorded , it seems likely that most unsuccesssfull pairs did not produce eggs at all. European Honey Buzzard Pernis apivorus

[free pdf] [dutch summary]