Are the birds dangerous for insect pollinators? The relationship between hymenopterans and the red-backed shrike

Abstract

Studies of the relationships between insectivorous birds and insects have focused on woodland habitats, where insects have usually been regarded as tree pests. But some insects are of the utmost importance to the human economy, especially hymenopterans, which pollinate plants such as fruit trees in orchards. Here we report on a 5-year study of the influence of the red-backed shrike Lanius collurio, a territorial insectivorous bird, on the numbers of hymenopterans in the extensively farmed landscape of eastern Poland. The relevant relationships were based on an analysis of the shrike’s diet and the numbers of hymenopterans in and beyond nesting locations. There was a weak but statistically significant relationship between the proportion of hymenopterans in the red-backed shrike’s diet and the place and time of prey capture, but this was dependent solely on the location of the shrike’s territory. No relationship was found between the numbers of hymenopterans and the presence of the red-backed shrike, agricultural site type or season effect. In conclusion, territorial bird species that occur in low densities probably have only a marginal influence on hymenopterans, including pollinators.