| Affiliation: | (1) Department of Polar Science, The Graduate University for Advanced Studies, 1-9-10 Kaga, Itabashi, 173-8515 Tokyo, Japan;(2) National Institute of Polar Research, 1-9-10 Kaga, Itabashi, 173-8515 Tokyo, Japan;(3) Department of Mechanical Engineering, National Defense Academy, 1-10-20 Hashirimizu, 239-8686 Yokosuka, Japan;(4) Department of Ecology, Evolution, and Behavior, University of Minnesota, 100 Ecology, St. Paul, MN 55455, USA;(5) Present address: National Marine Mammal Laboratory/NOAA, 7600 Sand Point Way N. E., Seattle, WA 98115 , USA |
| Abstract: | The under-ice behavior of two free-ranging female Weddell seals (Leptonychotes weddellii) was studied using geomagnetic, acceleration and velocity sensors at Big Razorback Island in McMurdo Sound, Antarctica. The seals' body angle and posture were calculated from the acceleration data and the heading from the geomagnetic intensity data. Together with swim speed, the seals' three-dimensional underwater dive path, heading and even posture were reconstructed for each dive. Each instrument was deployed for 2 days, during which time these females made multiple, deep ( m) dives, with average maximum depths of 236ᆯ m (n=4) and 244끁 m (n=40). Each seal appeared to choose a particular heading on which to descend. These headings were significantly different between seals and bouts (Watson's U2 test, P<0.05). These new instruments and methodologies are shown to provide valuable information on the fine-scale and complex movements of diving animals. |
