Fig. 7

Twelve outgoing (green) and incoming (blue) dead-reckoned trajectories from Magellanic penguins walking to and from their nest. Three variants of track advancement were used: a A VeDBA threshold (0.1 g) and constant m-coefficient (1.4) (b), depicted movement periods using the LoCoD method to identify steps (cf. Wilson et al. 2018) and constant m-coefficient (1.4) and c depicted individual steps within depicted movement periods, from which a constant distance estimate (0.16 m) was multiplied by step frequency (x̄ no. steps/s) (full details within Additional file 1: Text S4) (c). Note that the accuracy with respect to the radial distance can be evaluated by examining the track stops in relation to the shore-line. DBA-derived speed estimates were typically overestimated for incoming tracks, due to the birds being heavier (and thus impart greater DBA per stide cycle) after foraing. Tracks (from c) were GPS-corrected (d) (method = “distance”, dist.step = 5, VP.ME = TRUE, thresh = between 8 and 15 (depending on track length) approx. every 50 m). A portion of the GPS-corrected dead-reckoned tracks (bottom panel) are magnified (2 iterations) to show the difference in resolution of movement tortuosity, between GPS and dead-reckoned tracks