F 13 Prey engulfment in phocid seals studied with high-speed cameras and accelerometry
Kristina Skands Ydesen (1), Danuta Maria Wisniewska (1), Peter Teglberg Madsen (1) (1) Aarhus University kristinaydesen@msn.com
A key component in understanding the ecological role of marine mammal predators is to identify how, where and how much prey they capture in time and space. Satellite and archival tags on pinnipeds normally only render dive and geolocation information, and foraging events are then guestimated to take place in certain portions of the dive. However, specific movements of the head and jaws may provide reliable feeding cues by involving fast specific changes in acceleration. These might even be prey or context specific. To test this we trained harbour seals (Phoca vitulina) to wear mulitsensor Dtag3, with triaxial accelerometers sampled at 500Hz, on their head. Seals were trained to swim towards and catch prey in front of two underwater digital high-speed video cameras.
The results show that harbour seals apply both suction and raptorial feeding. Specific jerk signatures and the speed of suction feeding were found and related to actual prey captures documented by video. These results demonstrate that reliable feeding cues can be recorded using fast-sampled accelerometer tags on free ranging pinnipeds in their natural marine environments, holding a very promising prospect for long term studies of their foraging ecology and field energetics.