Range expansion and the possibility of an emerging contact zone between two subspecies of Chiffchaff Phylloscopus collybita ssp.
The Chiffchaff Phylloscopus collybita is represented in Sweden by two different subspecies; the northern well-established abietinus and the southern recently established collybita which has expanded its range northward during the past two decades. At present, an area approximately 500 km wide separates the two subspecies. In order to document differences between the northern and southern populatio
