Otters fishing: hunting behaviour and strategies

Abstract The usual hunting behaviour of otters in the sea consisted of swimming along the surface in daytime, diving in shallow water, and capturing small fish from their hiding places. Swimming speeds are described, as well as diving, handling, and eating of prey. Occasionally otters captured other animals such as aquatic birds, and they caught rabbits in their burrows. Otters were active during the day in Shetland and at night in many other places, because of the activity pattern of their prey species, the majority of which were caught when inactive. In the sea there was also a tidal effect, with otters foraging least during high tide. Success rates appear to be partly predetermined (otters fishing when there is a maximum likelihood of success). Differences in success rates between areas appeared to be related to prey size, and there was little variation in success rates between different depths of water and between seasons, with overall diving success around 27per cent in the sea.