Landscape use, foraging habitat selection and relationships to food resources in breeding little owls: recognizing the importance of scale for species conservation management

1. Landscape use and habitat selection, which result from the behavioural response of a species to patterns of resources availability, determine the distribution of individuals within populations at several spatial scales. We investigated habitat selection of adult little owls (Athene noctua) in relation to landscape configuration, habitat structure and prey abundance, with the main objective to provide evidence-based conservation guidance for this rare species. More specifically, we analysed the distribution of small rodent prey, and habitat selection by foraging adults in relation to prey abundance and to factors modulating prey accessibility, particularly vegetation height.

2. Habitat selection was assessed using VHF-telemetry and by quantifying the frequency of visits to artificial perches experimentally placed in different habitat types and structures. Relative prey abundance was estimated by transect counts of signs of vole presence also in different habitat types and structures.

3. Vole prey abundance was heterogeneous, varying in relation to the type of habitat present in the intensively-used agricultural matrix. Orchards, grassland and field margins provided rich vole prey supplies whereas their abundance was almost null in cropland. Little owls typically preferred orchards and field margins over grassland and cropland, while woodland was avoided. The frequency of visits to artificial perches indicated that foraging takes place preferably above low grass vegetation, and this irrespective of prey abundance.

4. Habitat selection and resource exploitation by little owls are structured at three hierarchical levels: 1) at landscape scale, orchards were the favourite habitat; 2) at habitat patch scale, areas with higher prey abundances were used over-proportionally; 3) at the foraging site scale, little owls selected patches with low grass vegetation.

6. Synthesis and applications. Orchards appear to be crucial for the persistence of little owl populations in farmland, which calls for their preservation against conversion into cropland or settlements. Within orchards, an ideal mosaic of habitat patches consists of dense grassland (un-mown meadows) alternating with short grassland (pastures or mown meadows), a fine-grained habitat complex which is likely to boost small rodent populations while it also increases their availability as prey for the little owl. As crucial food suppliers, field margins further constitute an important habitat feature.

Keywords: Resource patterns, food abundance, food accessibility, habitat patch, field signs, telemetry