Migration syndrome in individual bird migrants involves multiple behavioural, morphological and physiological adaptations, and migration performance may improve with experience and age.
In the autumn, most birds on migration are juveniles migrating for the first time while adults are repeating their migrations. Massive bird migration across continents and seas is one of the most spectacular phenomena in nature, involving billions of birds annually. Maps are created in ArcMap 10.132 (Mercator projection).
(C) Timing of autumn migration of displaced birds (red lines) compared to control birds (green lines). (B) Initial movements of 11 adult common cuckoos within the 15 days following displacement including endpoint directions and mean direction (black dots and solid black line in circle diagram) compared to direction towards origin (red dotted line), first and second staging areas (blue and green triangles) of control birds and first post-breeding migration departure direction (grey triangle) of control birds. Stars indicate final wintering destination and shaded areas indicate population-specific autumn staging areas considered as possible navigation targets. Tracking of displaced common cuckoos in time and space.: (A) Autumn migration routes of the six adult common cuckoos whose navigation was successfully monitored (red tracks) after being displaced from Denmark to Spain (arrow) compared to the migrations of eight adult non-displaced common cuckoos from Denmark and southern Sweden (green tracks: autumn vs spring routes indicated as solid vs dotted lines respectively).