The dependence of long-distance migration to North Norway on environmental conditions in the wintering area and en route

Abstract

The onset of bird migration may be under partial endogenous control whereas the timing of movement is flexible with weather and conditions faced by the moving birds being the ultimate cause of variability of arrival dates. This study shows that the early arrival dates of two of three long-distance passerine spring migrants (Willow Warblers Phylloscopus trochilus and Chiffchaffs P. collybita) in North Norway were unrelated to climatic conditions at the start of their migration in Africa and en route through Europe until they reached Scandinavia. Although climate in W Africa may have affected departure dates, the timing of arrival of the first Pied Flycatchers Ficedula hypoleuca seemed to be unrelated to conditions along the whole route, including the target area.