Arctic and Antarctic seals are able to inhabit areas of complete ice cover by virtue of their ability to make and maintain breathing holes through the ice. The sensory system of these marine mammals is crucial for locating these holes while the animal is under ice. The difficulty of working with these animals in the natural environment has resulted in few studies which address the orientation and navigation capabilities of marine mammals. This project involves the refinement of acoustic remote sensing technology and its application to Weddell seals in the natural environment in Antarctica. Drs. Wartzok and Elsner have developed a system for acoustically tracking seals as they swim under the ice. Preliminary studies have indicated that vision plays a dominant role in under-ice navigation when this sensory modality is available. More detailed and quantified studies of the roles vision, audition and vibrissal senses play in under-ice navigation and hole finding by seals will be conducted. In addition, the ranges at which seals can visually detect new breathing holes will be correlated with the laboratory-based limits of visual sensitivity and the field measured light extinction coefficients will be determined. Additional research will quantify the ranges at which seals can use auditory cues to detect new breathing holes and what types of auditory cues they use. Once the importance of audition for these animals in their natural environment is determined, the impact of anthropogenic sound on the biology of these animals can be inferred. The range over which vibrissae function in hole finding will be determined. The tracking of more than one seal under the ice will provide an understanding of under-ice behavioral interactions.
