Broedende roofvogels in Salland in 1995

Two monitoring plots were covered in Salland (part of the province of Overijssel) in 1995, i.e. Diepenveen-Olst (6100 ha, of which 22% woodland) and Ooslermaet (2200 ha, 33% woodland), both situated in the province of Overijssel. Of Honey Buzzard, 5 territories were found, with 3 nests (each 2 fledglings). Onset of laying was 24 May, 25 May and 3 June respectively. Eleven territories of Goshawks contained 9 occupied nests; all females and 10 out of II males were in adult plumage. Mean onset of laying was 3 April (n=7. range = 26 March-11 April). Clutch size was 4x 3, 3x 4 and 1x 5 eggs, number of fledglings on average 2.7/successfuI nest (n=9). Sex ratio among large nestlings was fifty-fifty (n=24). Twenty-two territories of Sparrowhawks contained 19 occupied nests. Mean onset of laying was 4 May (n=14, range = 24 April-22 May). Mean clutch size was 3.9 eggs (2x 2, 3x 4, 3x 5). Two nests failed in the egg stage, another nest in the nestling stage. Mean number of fledglings/successful nest was 3.4 (n=14). Sex ratio was in favour of males (51%. n=47). In 39 territories of Common Buzzards, 27 nests were found. Mean onset of laying was 11 April (n=12, range = 5-23 April). Mean number of fledglings/successful nest was 1.9 (n=14). Sex ratio was even (n=18 large young). Two nests failed in the egg stage, one nest in the nestling stage. In 3 out of 5 territories of Hobbies nests were located, onset of laying being 8, 16 and 20 June. Clutch size was 1x 2 and 2x 3 eggs. One nest failed in the early nestling stage, the other raised 2 and 3 young.