[Recording the feeding behavior of freely moving animals using the example of freely diving Weddell seals (Leptonychotes weddellii)].

During the antarctic summer 1990, the pattern of food intake in comparison to diving-activity was investigated on adult Weddell seals. Diving depths were recorded by a time-depth recorder (TDR). The TDR is a free programmable electronic datalogger, which can store data on up to 5 channels. It was fixed on the fur of the seal, ensuring that no longer lasting irritation of the animal was caused. The pattern of food-intake was monitored by measuring the jaw-movements, using strain gauges for recording the deformation of the muscles by mastication. After electronic amplification and filtering, the frequency of jaw-activity within a measuring period was recorded one channel of the TDR. By simultaneously observing the diving depths, these data may lead to conclusions about chewing patterns of the seal in water depths where they catch prey. The graph of these data and the mathematical evaluation by Fourier analysis and Plexogramme show a close correlation between diving depth and jaw-activity.