Fig. 4

a Migration speeds over NDVI with lines of best fit, during day and night, for all segments, and for those segments described as active migration (migration speeds > 5 km/h), but excluding transitions between day and night. Migration speeds were significantly slower over areas with higher NDVI, with slower migration speeds overall recorded at night suggesting birds roost during most nights. By including only presumed active migratory movements (migration speeds > 5 km/h), migration speeds were typically higher at night than during the day. b Migration speed over latitude for autumn and spring, including night, day and transition flights between day and night. There are sites at specific latitudes with concentrations of points, which indicate stopovers for roosting and foraging