Common pastures are important refuges for a declining passerine bird in a pre-alpine agricultural landscape

Abstract

Agricultural landscapes play an important role in biodiversity conservation. The Tree Pipit (Anthus trivialis) was once a widespread breeding bird in European farmlands. Today, however, its numbers are sharply declining in most European countries. The aim of our study was to compare territory densities of Tree Pipits in common pastures and control plots in the surrounding pre-alpine agricultural landscape in southern Bavaria (Germany). Additionally, we determined the drivers of territory and home-range establishment in Tree Pipits. Habitat composition in common pastures and control plots reflected distinct differences in land-use intensity. Common pastures had larger areas of nutrient-poor habitats and higher landscape diversity compared to control plots. In line with this, we detected a clear response of Tree Pipits to differences in habitat composition. Territories were nearly exclusively found in common pastures. Within the common pastures, Tree Pipits preferred those parts that had higher landscape diversity and, additionally, at the territory scale, larger areas of groups of trees. The common pastures are important refuges for the threatened Tree Pipit in the pre-alpine agricultural landscape of the study area. In contrast to the control plots, the common pastures provided (i) sufficient suitable song posts and (ii) heterogeneous vegetation with appropriate nesting sites and a high availability of arthropod food resources. Our study corroborates findings from other studies across Europe highlighting the prime importance of traditionally used wood pastures for the Tree Pipit, and for biodiversity in general.