Fig. 3

Regression between proportion of overlap with water bodies and five variables related to a fly-and-forage strategy calculated for traveling segments of autumn (solid line) and spring (dashed line) migration of tracked Caspian terns (12 adults and 27 juveniles represented as circles in autumn and 12 adults as triangles in the spring). Proportion of overlap with water bodies was measured as the proportion of pixels in a 5 km buffer around traveling segments with identified aquatic habitats according to MODIS land covers (see methods). Orange (autumn) and green (spring) lines signal the variables for which the proportion of overlap with water was a predictor with effects that did not overlap with zero in a 95% confidence interval (CI), while grey lines show predictors with effects that overlapped with zero (95% CI). Horizontal light blue line in the graph of day to night flight ratio indicates when the ratio value is equal to 1, since a value greater than 1 represents migratory flight predominantly during the day and less than 1 during the night. See Additional file 1: Fig. S7 for correlation graphs of all explanatory variables with effects distinguishable from zero