Drentse Wespendieven Pernis apivorus nestelen steeds vaker in Japanse lariks Larix leptolepus

Over the period 1979-99, Honey Buzzards in the province of Drenthe used six tree species for nesting (Appendix 1), mostly Douglas fir and Japanese larch. Although nesting in Douglas fir is still preferred in the late 1990s (33% of the nests in 6% of the wooded area), nesting in Japanese larch showed a distinct increase over the years (Figure 1) from 0% in 1979-84 to 45% in 1994-99 (in 17% of the wooded area). The proportion of egg-laying pairs raising fledglings in Douglas fir nor Japanese larch showed any changes in 1979-99, being respectively 85% (n=47) and 72% (n=25; Appendix 2), and is therefore thought not to have acted as a stimulus for the remarkable change to nesting in Japanese larch. It is argued that Japanese larch, already for several decades the preferred nesting tree in Goshawk Accipiter gentilis and Common Buzzard Buteo buteo, has only recently become suitable for nesting Honey Buzzards. Larch plantations in Drenthe were planted in the 1940s. Maturation of larches in the last decade resulted in denser crowns with a higher proportion of misfigured treetops. These latter -often secluded- sites are clearly preferred by Honey Buzzards, contrary to Goshawks and Common Buzzards which make bulky nests halfway up the trunk. Both sexes of the Honey Buzzards start foraging in the third week of life of the nestlings, attending the nest sporadically and for short periods afterwards (unless wasp densities are high, and especially females may linger near the nest for longer periods). In the Goshawk-riddled forests of Drenthe, nest protection through cover is therefore a priority. Such cover in larches has only recently become available after sufficient maturation of the larch plantations.