Additional File 1.
Walrus using its flippers and muzzle to expose bivalves. Young Sound, Northeast Greenland 2001. (Filmed by Göran Ehlmé). The movie clip of feeding walruses has been zipped in order to reduce the size and hereby making it more suitable for readers to download when viewing. Suggestion of different software to use for viewing the clips: Windows Media player, Real Player or QuickTime player.
Format: ZIP Size: 6.3MB Download file
Levermann et al. BMC Ecology 2003 3:9 doi:10.1186/1472-6785-3-9