Horizontal Area-Restricted-Search and Vertical Diving

11 With technical advances in wildlife telemetry, the study of cryptic predators’ responses to prey 12 distribution has been revolutionised. Considering marine predators, high resolution tagging 13 devices were developed lately to collect long and precise diving datasets. In this study, we 14 investigated, at fine temporal and spatial scales, changes in the horizontal movements and 15 diving patterns of a marine predator, the southern elephant seal. Satellite tracking data collected 16 on nine seals were processed with switching state-space models. Seals’ body condition, as a 17 proxy for foraging success, was estimated through changes in drift rate from Time Depth 18 Recorder (TDR) data. We identified (1) statistically distinct behavioural modes along the 19 1 ha l-0 06 59 58 0, v er si on 1 18 J an 2 01 2 tracking data (intensive vs. extensive foraging modes) and (2) dive classes from the TDR diving 20 data (drift, exploratory, shallow active and deep active dives). Mass gain over the animals’ 21 foraging trip was also linked with the proportions of intensive foraging zones and dive classes. 22 Active dives, associated with vertical foraging and chasing, were more numerous when the seals 23 were in intensive foraging mode. Improved body condition and mass gain of seals were also 24 associated with the occurrence of intensive foraging mode and, within the vertical dimension, 25 with sets of highly active dives. In conclusion, proportions of dive classes displayed by the seals 26 proved to vary according to their horizontal behaviour. The results allow us to conclude that 27 intensive foraging detected from surface tracking data is a good predictor of the diving activity 28 and foraging success occurring in the vertical dimension. 29