The Honey-Buzzards of the Sensebezirk: First Findings on Density, Diet, Reproduction and Food Competition in a Swiss Population of Honey-Buzzard Pernis Apivorus
22 Pages Posted: 13 Feb 2020
Date Written: December 12, 2019
In 2018 a nest of Honey-buzzard Pernis apivorus was found during a research project on Red kites Milvus milvus in Switzerland in an area where the cantons of Bern and Fribourg border. The diet was analysed by using a camera trap at the nest. In 2019 I started a private project to get an insight in Honey-buzzard density and reproduction in the area.
1)Territory density and reproduction: In 2018 one nest was found occasionally where two chicks fledged. In 2019, 8 territories were mapped in 54.3 hours of observing at high viewpoints, covering ca. 100 km2. At 7 territories the reproduction could be determined with a moderate certainty, resulting in only one successful territory where one young was raised.
2)Diet: By following nests with camera traps, diet was determined by number of prey items brought to the nest per adult. Two successful nests were followed, one in 2018 and one in 2019 during the chick rearing phase. Common wasp Vespula vulgaris and grey coloured combs, presumably dominated by European wasp Vespula germanica formed the most frequently delivered prey to both nests, but the share of the overall prey was bigger on the nest of 2018 than on the nest of 2019, resp. 68,9% and 60,1%. Also, the mean size of the combs per aforementioned wasp species was bigger in 2018 than in 2019. In 2019 more alternative prey were brought to the nest, like Hornet Vespa crabro, Bumblebee Apinae and one Vole Arvicolinae.
3)Wasp predation: Predation on social wasps was followed with camera traps at occasionally found wasp nests, three in 2018 and one in 2019. Honey-buzzards appeared in front of the camera at two of the three nests found in 2018, 5 individuals, but none started digging nor harvested from the nests. Badger Meles meles, Polecat Mustela putorius, Red fox Vulpus vulpus, and Pine marten Martes martes were recorded showing interest without predating on the nests. The single nest found in 2019 was predated completely by a Pine marten Martes martes.
Keywords: honey-buzzard, raptor, pernis, pernis apivorus, parental care, diet
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