Figure 2.

Risso's dolphin foraging dives track the diel vertical migration of the deep scattering layer (DSL). Diel pattern of (a) the number of spin and non-spin foraging dives of the tagged individuals (tag data; orange circles: number of tagged individuals), (b) the proportion of observation records with spin dives (visual observation data; orange circles: number of observations (obs)), (c) depth of prey capture attempts, as identified by buzzes of the tagged individuals, tracks the depth of the DSL (blue layers, showing the depth contour of the upper and lower DSL). (a) Timing of tag records (10.00–03.00) is determined by the period of tag attachments; (b) period of visual observation records (7.00–21.00) is confined to daylight hours. Note: (b) n = 5 and n = 6 visual observations at 7.00 and 21.00.