The contribution of invertebrate taxa to moorland bird diets and the potential implications of land-use management

We reviewed the literature to determine the importance of invertebrates for moorland-breeding birds and considered our findings with respect to the conservation of such species in the UK. The diets of many moorland birds consist predominantly of invertebrates, with a wide range of taxa recorded in the diets of moorland birds during the breeding season. Relatively few taxa (Arachnida, Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera and Oligochaeta) were widely taken, with Diptera and Coleoptera being the most important. Among these latter two insect orders, Carabidae, Curculionidae, Elateridae and Tipulidae were the most important families. Comparisons of the diets of bird families, treated separately according to whether data were derived from adults or chicks, showed that waders take more interstitial invertebrates than passerines, which themselves take more foliage invertebrates. Although we lack detailed experimental data with which to demonstrate the direct effect of particular moorland management prescriptions on some of these key invertebrate taxa for breeding birds, available data suggest that management regimes that create a mosaic of habitats are likely to be most beneficial. In particular, heterogeneity in vegetation structure and species composition, and the presence of wet flushes associated with the synchronized spring emergence of adults of certain insect species, are likely to increase invertebrate food resources for birds.