Fig. 3

The track of a tree swallow as estimated from 2-min fixing interval data by classic approach (GeoLight, grey line and dots) and FLightR. Inset shows Tree Swallow range in North America. The medians of twilight positions estimated by FLightR are coloured by the month of a year (colours for each month are illustrated with pie chart). In June a bird was tagged on the breeding grounds at the Long Point Bird Observatory in Ontario, Canada. July 19 it left breeding ground and moved to the stopover site in Virginia (segment A). At 1or 2 August it moved to coastal area on the border of North Carolina and Virginia (segment B), where remained stationary until end of October. 23–24 October the bird departed towards a stopover site in South Carolina (segment C), where it stayed for a week and then continued south to Cuba (segment D). The bird remained in Cuba till the end of March, with one exception for flight to the vicinity of the Bimini Islands (segment E). On 28 of March bird left wintering grounds and migrated to the North Carolina/Virginia site (segment F) and after a short stopover there moved straight to the breeding grounds (segment G). Note that no spatial or behavioural masks were used for the FLightR run, so positions were allowed to be everywhere. Raw GeoLight estimates shown on the figure should not be interpreted as a positions and inference can be made only for most likely location during stationary periods, new functions in GeoLight 2.0.1 are available now for the estimation of these most likely stationary locations (Lisovski & Liechti, pers. comm). Tree swallow range image is courtesy of Birds of North America: Cornell Lab of Ornithology