Under-ice movements and the sensory basis of hole finding by ringed and Weddell seals

• Published in: Canadian Journal of Zoology
• Main Authors: Wartzok, Douglas, Elsner, Robert, Stone, Henry, Kelly, Brendan P., Davis, Randall W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1992
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Arctic; Antarctic; Weddell; Antarc*; Leptonychotes weddelli; Phoca hispida; ringed seal; Weddell Seals
• Online Access: http://dx.doi.org/10.1139/z92-238; http://www.nrcresearchpress.com/doi/pdf/10.1139/z92-238

Arctic ringed seals (Phoca hispida) and antarctic Weddell seals (Leptonychotes weddelli) were tracked using an attached acoustic tag during their under-ice movements at isolated experimental sites with varying numbers of novel breathing holes. Both natural and artificial visual landmarks were used by the seals during their dives. Seals deprived of vision through blindfolding greatly restricted their diving. Blindfolded seals responded to supplied acoustic cues and moved toward them. Prior to swimming toward an acoustic cue, the animals often swam at an angle to the direct line to the source of the acoustic cue. This movement could have provided information on the distance to the source of the sound. After executing this presumed ranging behavior, the seals swam directly toward the acoustic cue up to 4 km away. The contribution of vibrissal sensation to location of an open hole was investigated in blindfolded ringed seals. Seals farther than 1 m from an open hole were unable to find the hole without an acoustic cue. Vibrissal sensation apparently contributed to centering the blindfolded ringed seal within a breathing hole, but not to locating the hole. Weddell seals were able to maintain straight-line tracks for several hundred metres out from and back to a hole, were able to follow the same path on subsequent trips separated by up to 64 h, and continued using established routes between holes even though shorter, direct routes were available. The spatial memory implied by these observations is postulated to be a mechanism by which seals are able to move from one breathing hole to another under ice during dark polar winters.