Biotoopvoorkeur en broedresultaten van de Boomvalk Falco subbuteo in oostelijk Midden-Limburg

Hobbies were studied during 1986-94 in an area of 15,000 ha in the southern part of The Netherlands. This area mainly consists of farmland, with some scattered forests and heaths. Overall density of Hobbies was 0.07 pairs/100 ha in 1994, slightly higher than elsewhere in the province of Limburg (0.03-0.06 pairs/100 ha in four other large study plots). Most territories were located in poplar plantations in small-scale farmland (84%), with only 13% in mixed woodland and heaths and 3% in open farmland. The riverbeds of Maas and Roer were the preferred breeding areas (64% of all territories), mainly because of the occurrence of poplar plantations. Nesting in poplars could be in solitary trees, plantings along roads and in woodlots of up to 5 ha, Where Hobbies bred, forests lacked a shrub layer. Of 69 nesting sites, 58 were in poplars, nine in Scots pine and two on electricity poles. Nest providers were Carrion Crow (n=68) and Common Buzzard (n=1). In three instances was a nest used in two consecutive years. Mean number of nestlings in 1987-94 was 2.7 (Table 1), with very little variation between years. Mean onset of laying was 9 June (SD=6 days), with 28 May and 26 June as first and last date respectively.