Variability in nestling diet of European hoopoes: annual and sampling effect

Abstract

The aim of the study is to get a representative picture of the diet composition of hoopoes in vineyards as specific man made habitats in Central Europe. Therefore diet composition and its interannual variability and the representativeness of two sampling techniques have been studied in hoopoe nestlings, Upupa epops during two breeding periods. Altogether, 1081 prey items were identified and classified into ca. 90 species, 32 families and 11 orders of invertebrates. Regarding interannual variation, the number of prey items per nestbox did not differ between years in the same nestboxes. A within-nest comparison between the two sampling methods revealed a significant difference in the number of prey items for four categories, namely orthopterans, “other beetles”, arachnids and lepidopterans. Comparing the two sampling methods, revealed reversed results regarding the proportion of the main prey categories; e.g. scarabaeid larvae, abundant in the camera samples, were less frequent in faeces, whereas “other beetles” were common in faeces, but were only occasionally detected in the camera recordings. The occurrence of the earthworms in the hoopoe's food is novel. We finally discuss advantages as well as the drawbacks of both methods and the possibility to use both these contrasting, but non-invasive techniques.