Habitat Structure of Temporary Settlement Areas of Young Saker FalconFalco cherrugFemales during Movements in Europe

Abstract

During 2008–2011, nine juvenile Saker Falcon Falco cherrug females were tagged with satellite transmitters in Slovakia. Satellite telemetry provided new insights into the juveniles' movements. In this study we present the use of temporary settlement areas (TSAs) during the movement of the tracked juveniles. We characterized natal areas (NAs, the first TSA in the life cycle of juvenile, restricted to the nest) and TSAs as areas where the distance between the all-night perches did not exceed ten kilometres and where a particular bird spent at least five consecutive days. In these areas 3 types of polygons were identified in relationship to the area of use — a home range (95% kernel polygons), a core area (50% kernel polygons) and an overall used area (100% minimum convex polygons). The overall used areas were highly variable and probably influenced by exploratory flights, when sakers fly out of their home ranges and come back at night. Habitat preference was then analysed in the TSAs for a better understand of juvenile habitat requirements. For habitat preference a CORINE raster image (version 13/2006) with a resolution of 100 × 100 m was used. In the TSAs 14 habitat categories were recorded, but for statistical analysis only 8 habitat categories were used. Conservation status of the NAs and TSAs was also described. Arable land represented the dominant habitat category in the TSAs (mean 67.64% for overall used areas, and 80.94% for core areas). A significant difference was found in the habitat structure of the overall used areas, the home ranges and the core areas. All of the tracked Saker Falcons preferred arable land, while avoiding two habitat categories — forests and scrub and/or herbaceous vegetation associations. The number of days spent in the TSAs (9–139 days, mean = 46.7 days) and in the NAs (36–134 days, mean = 62.3 days) varied by different individuals. Most of the NAs and TSAs are at least partially covered by protected areas, only four areas had no conservation status.