Northern elephant seals reside terrestrially on the sandy, rocky or muddy shores of the coastline, particularly on offshore islands. They typically aggregate in large groups while on land. These animals spend only 10% of their time on land, during reproduction and moulting. The other 90% is spent in the water, diving and foraging for food, and only 11% of this time in the water is spent at the surface. This means that an extraordinary 85-90% of their time is spent at sea and under water. These mammals can dive exceptionally deep, to 500 to 600 meters (almost 1 mile) on average and to record depths of over 1500 meters for extended periods of time (20 to 70 minutes). (Andrews et al., 2000; Bonner, 1990; Davis et al., 2001; Delong and Stewart, 1991; Lawlor, 1979; Le Boeuf et al., 2000)
- Lawlor, T. 1979. Handbook to the Orders and Families of Living Mammals. Eureka, California: Mad River Press.
- Andrews, R., D. Costa, B. Le Boeuf, D. Jones. 2000. Breathing frequencies of northern elephant seals at sea and on land revealed by heart rate spectral analysis. Respiration Physiology, 123: 71-85.
- Bonner, W. 1990. The Natural History of Seals. New York, NY: Facts On File, Inc..
- Davis, R., L. Fuiman, T. Williams, B. Le Boeuf. 2001. Three-dimensional movements and swimming activity of a northern elephant seal. Comparative Biochemistry and Physiology Part A, 129: 759-770.
- Le Boeuf, B., D. Crocker, D. Costa, S. Blackwell, P. Webb. 2000. Foraging ecology of northern elephant seals. Ecological Monographs, 70 (3): 353-382.
- Delong, R., B. Stewart. 1991. Diving patterns of northern elephant seal bulls. Marine Mammal Science, 7 (4): 369-384.