Satellite tag-derived movements of two Antarctic blue whales with Southern Ocean frontal positions (Park and Durand 2019, Park et al. 2019) in grey. From south to north, these are: Southern Boundary, Southern Antarctic Circumpolar Current, Polar, Subantarctic and Northern Boundary. a) State space model derived location estimates by date. Black points indicate satellite tag deployment locations. Each track is labelled by PTT and by track segment for PTT 123223. b) State space model derived location estimates with behavioural context – blue points indicate transit-like behaviour and orange points indicate area restricted search (ARS)-like behaviour.