Feeding behaviour of free-ranging walruses with notes on apparent dextrality of flipper use

• Published in: BMC Ecology
• Main Authors: Ehlme Göran, Galatius Anders, Levermann Nette, Rysgaard Søren, Born Erik W
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2003
• Subjects: Ecology; QH540-549.5; Greenland; The Muzzle; Odobenus rosmarus; walrus*
• Online Access: https://doi.org/10.1186/1472-6785-3-9; https://doaj.org/article/88c02c01477f4f01a0615ad7f57bbc95

Abstract Background Direct observations of underwater behaviour of free-living marine mammals are rare. This is particularly true for large and potentially dangerous species such as the walrus ( Odobenus rosmarus ). Walruses are highly specialised predators on benthic invertebrates – especially bivalves. The unique feeding niche of walruses has led to speculations as to their underwater foraging behaviour. Based on observations of walruses in captivity and signs of predation left on the sea floor by free-living walruses, various types of feeding behaviour have been suggested in the literature. In this study, however, the underwater feeding behaviour of wild adult male Atlantic walruses ( O. r. rosmarus ) is documented for the first time in their natural habitat by scuba-divers. The video recordings indicated a predisposition for use of the right front flipper during feeding. This tendency towards dextrality was explored further by examining a museum collection of extremities of walrus skeletons. Results During July and August 2001, twelve video-recordings of foraging adult male walruses were made in Young Sound (74°18 N; 20°15 V), Northeast Greenland. The recordings did not allow for differentiation among animals, however based on notes by the photographer at least five different individuals were involved. The walruses showed four different foraging behaviours; removing sediment by beating the right flipper, removing sediment by beating the left flipper, removing sediment by use of a water-jet from the mouth and rooting through sediment with the muzzle. There was a significant preference for using right flipper over left flipper during foraging. Measurements of the dimensions of forelimbs from 23 walrus skeletons revealed that the length of the right scapula, humerus, and ulna was significantly greater than that of the left, supporting our field observations of walruses showing a tendency of dextrality in flipper use. Conclusion We suggest that the four feeding behaviours observed are typical of walruses in ...