Foraging behaviour of Cape clawless otters (Aonyx capensis) in a marine habitat

The foraging behaviour of Cape clawless otters Aonyx capensis was investiga ted. Factors included: duration of dives, recovery times, processing times, hunting success, per cent time at the surface, and time foraging before ea ch catch. Observations were made during the day on solitary adult A. capens is in a marine environment in False Bay, South Africa. There were significa nt differences in duration of unsuccessful dives, recovery times, and proce ssing times as well as successful dives with various depths. Aonyx capensis prefer hunting at depths of 0.5-1.5 m. This is despite having a higher hun ting success, catching larger, more energy-rich prey (fish), and shortest t ime foraging per catch, at depths of 1.5-2.5 m. Some of the data presented support the optimal breathing hypothesis, which predicts that both surface and dive times should increase for dives of greater depths. However, diving efficiency does not decrease with increasing depth, and percentage time at the surface does not increase with increasing depth. These are contrary to the optimal breathing hypothesis.