Skylark ( Alauda arvensis) utilisation of micro-habitats in spring barley fields

Abstract

Within-field habitat utilisation by skylarks Alauda arvensis was studied in spring barley crops by means of radio-tracking and visual sighting. Arthropod food abundance and dropping densities were monitored within three different micro-habitats. The effect of maintaining open areas within a cereal field on local skylark densities was examined on two experimental fields. Radio-tracked skylarks showed a strong preference for the tramline micro-habitat. There was a positive correlation between crop height and the proportion of birds located in tramlines. This preference was supported by visual observation of ascending and descending birds as well as the mean density of droppings found in the three habitat types. Tramlines and unsown plots were utilised significantly more than expected and the crop was avoided. The density of arthropod food items was highest in crop and lowest in tramlines and unsown plots. This indicates that the skylarks' preference for tramlines and unsown plots was probably due to unhindered ground locomotion, facilitating detection of prey items, rather than prey density. Artificially maintained open areas had a positive effect on the density of breeding pairs and territorial males, and on the duration of the breeding period. These results suggest a positive effect of the open areas within field crops on the number of re-nesting attempts. The management implications of the results are discussed.