Winter occupation of breeding territories of Peregrine Falcon Falco peregrinus in western Sweden 2000/2001–2004/2005

Abstract

During five winters (2000/2001–2004/2005), 24 breeding territories of Peregrine Falcon Falco peregrinus in Bohuslän, Västergötland and Halland in western Sweden were visited at least once. At these territories 10–14 (mean = 12) Peregrines were observed each winter. All birds that were aged were adults and the sex ratio was 52% females and 48% males. At least 50% of the breeding territories were estimated to be occupied by Peregrines each winter. Five of seven territories which usually were occupied in winter had a long record of breeding Peregrines. Some important factors that cause Peregrines to stay during the winter in their breeding territories in western Sweden are probably the mild climate, the abundance of prey (for instance Jackdaws Corvus monedula) and the competition for breeding territories.