Fig. 1

Migration routes of barn swallows breeding in south-central Europe (northern Italy and southern Switzerland) in 2010–2012. a Post-breeding (Europe–Africa) autumn migration routes (n = 73); b regional-scale movements between multiple stationary periods in Africa during boreal winter of itinerant individuals (n = 8); c pre-breeding (Africa to Europe) spring migration routes (n = 60). Trajectory colours represent different years (darker: 2010; lighter 2012). Dots indicate position of the first (post-breeding migration) or the last (pre-breeding migration) stationary period north of the 45° N (where the SE, SW and N populations are located) or south of 17° N (broken horizontal line, southern margin of the Sahara Desert; see Methods). Triangles in panel b represent the position of the main non-breeding stationary period (filled triangle) and of the secondary stationary period (open triangle) of itinerant individuals; downward pointing triangles: first non-breeding stationary period south of 17° N; upward pointing triangles: last non-breeding stationary period south of 17° N