3) and the number of wiggles (Fig. 4). Vertical speed and body angle followed the same pattern of variations during descent phases. Firstly, they increased from 1.0 m s −1 and 45° to a maximum (up to 1.8 m s −1 and 80°) at about half of the maximum dive depth, then started

to decrease as the bird approached the bottom. When considered below a 5-m depth step in the water column, the birds’ vertical speed and Doxorubicin chemical structure body angle were positively affected by both maximum dive depth (Fig. 3a,e) and number of wiggles during the previous dive (Fig. 4a,e). Swimming speed during descent sharply increased in the first 5 m, then slightly increased before reaching a maximum value at about 2.0 m s −1 (Fig. 3c). Flipper stroke frequency decreased during descent from around

2.0 Hz in the first 5 m to around 1.0 Hz at the beginning of the bottom phase, and was positively affected by maximum dive depth (Fig. 3g). Vertical speed during ascent increased except during the last 30 m where it slightly decreased, and was positively affected by both maximum dive depth (Fig. 3b) and number of wiggles during the bottom of the current dive (Fig. 4b). Swimming speed during ascent remained constant PF-02341066 solubility dmso at about 2.0 m s −1 until a depth of 30–40 m where it started to increase, reaching a maximum value of 2.5–3.0 m s −1 at a depth of 15–20 m, and was positively affected by maximum dive depth during the last 40 m (Fig. 3d). Body angle during ascent increased except during the last 40 m where it quickly decreased, and was positively affected by both maximum dive depth (Fig. 3f) and number of wiggles during the bottom of the current dive (Fig. 4f). Flipper stroke frequency during ascent continuously decreased from around 0.9 Hz at the end of the bottom period to 0 Hz at the surface. The suppression of stroke movements appeared at a depth equal to approximately 35% of maximum dive depth. Ascent flipper stroke frequency was negatively affected by the number of wiggles

during the bottom phase of the current ROS1 dive (Fig. 4h). Theoretical studies of diving behaviour have proposed strategies that maximize the proportion of time spent submerged mostly based on the use/recovery of oxygen reserves (Carbone & Houston, 1994). Thus, divers should maximize the time spent in a favourable patch at depth by maximizing the oxygen store available at the foraging depth. If diving predators increase time spent foraging in a patch, that is at the bottom of a dive, they should in turn reduce the time spent commuting or recovering at the surface. The present study shows that deep divers such as king penguins can adjust their transit time from the surface to the bottom of a dive in response to the success of the previous dive, and from the bottom to the surface in response to the success of the current one.