Fig. 1

Variation in the nocturnal departure time of different songbird species as obtained from different radio tracking studies. Bean plots illustrate variation in nocturnal departure timing in relation to sunset (left side) and the proportion of the night (right side). Extension of the bean plots represent kernel density estimations of the distribution of individual departures, given as small lines in the plot. Broad lines represent the median nocturnal departure time of the respective group. Gray bean plots: autumn migration; white bean plots: spring migration. European Robin (Erithacus rubecula) at Rybachy, Russia [39] and Falsterbo, Sweden [46]; Song Thrush (Turdus philomelos) at Falsterbo, Sweden [46]; Swainson’s Thrush (Catharus ustulatus) at Long Point, Ontario, Canada [49, 50]; Eurasian Reed Warbler (Acrocephalus scirpaceus) at Falsterbo, Sweden [37]; Willow Warbler (Phylloscopus trochilus) at Falsterbo, Sweden [46]; Garden Warbler (Sylvia borin) at Falsterbo, Sweden [46]; Black-throated Blue Warbler (Setophaga caerulescens) at Long Point, Ontario, Canada [49, 50]; Northern Wheatears (Oenanthe oenanthe) at Wales, Alaska, USA [44] and on Helgoland, Germany [42, 43]; Sedge Warbler (Acrocephalus schoenobaenus) at Rybachy, Russia [48]