Wespendief Pernis apivorus plundert nest van Hoornaar Vespa crabro, of: sociale wespen als voedsel van Nederlandse Wespendieven

On 10 July 2014, an adult male Honey-buzzard was photographed whilst depredating a hornet’s nest Vespa crabro, situated in a thick branch of a dead poplar Populus sp. on an estate in the province of Utrecht, central Netherlands. The bird was able to open the nest with its bill, because the nest was excavated on the upper side of a diagonal branch that permitted easy approach by the Honey-buzzard. Normally, hornets use cavities in the bole of a tree, which hampers/prevents avian predation. In fact, out of 3352 wasp combs collected on hundreds of Honey-buzzard nests in The Netherlands in 1971-2013, only 0.9% referred to those of Vespa crabro. Ground-nesting social wasps (Vespula vulgaris, V. germanica, V. rufa) constituted 97% of all identified wasp combs, with three Dolichovespula species and Vespa crabro, i.e. species nesting in cavities or building hanging nests on trees or shrubs, responsible for the remaining 3% (Table 1). Another 2833 wasp combs could not be identified to species, but as these almost exclusively constituted grey-combed nests, it is likely that the majority of unidentified combs had belonged to V. germanica. Clearly, in its breeding quarters the European Honey-buzzard is a digger, not a picker. In the entire diet, as evident from prey remains found on nests (hence a biased sample) in The Netherlands in 1971-2013, social wasps accounted for 6185 preys (intact combs), i.e. 95% of all prey items, the rest consisting of combs of bumblebees (N=47), one comb of Honeybee Apis mellifera, birds (N=141, mainly nestlings of Woodpigeon Columba palumbus and thrushes Turdus sp.), frogs (N=74, three species), Common Toads Bufo bufo (N=13), Slow Worms Anguis fragilis (N=21), one Grass Snake Natrix natrix and two lizards (two species).