Ethology and Behavioral Ecology of the Walrus (Odobenus rosmarus), with Emphasis on Communication and Social Behavior

Large tusks characterize the extant walrus (Odobenus rosmarus) and its extinct relatives. Those socially selected organs vary between the walrus and fossil relatives, intraspecifically, and between the sexes. Tusks are used in innumerable interactions on land and in water, including fights during rut. “Play fighting” appears even in young calves that lack tusks. Complex sounds resembling those of rutting males underwater and at the water surface occur throughout the year; some are produced by young males. Short-range graded communication (acoustic; tactile; chemical) is important but has scarcely been investigated. Underwater communication within traveling or feeding groups is likely to occur, but also has not been investigated. Specialized integumentary “bosses” on the chests and necks of adult males probably function in optical signaling. Knowledge of movements, diving, feeding, rhythms, time-activity budgets, and effects of weather on behavior has increased greatly; little information is available on associated finer-scale behavioral structure. Field observations on benthic feeding and seabird predation have revealed previously unknown and ecologically interesting behaviors. Walruses are the most gregarious species of pinniped and are almost always in groups in the water and on land or ice, and in extensive body contact with one another. Gregariousness enables huddling for warmth and cultural transmission of information. Many anecdotes from over more than a century suggest more complex social structure than usually assumed, and the species expresses extensive social play that continues into adulthood. In light of those traits, plus the species’ high intelligence and longevity, low reproductive rate, and site fidelity, it seems timely to investigate cultural aspects of the walrus social system.