Diving and haul-out patterns of walruses (Odobenus rosmarus) on Svalbard

• Main Authors: Gjertz, Ian, Wiig, Øystein, Lydersen, Christian, Griths, D., Krat, B. A.
• Format: Dataset
• Language: unknown
• Published: Norwegian Polar Institute 2008
• Subjects: BIOTA; biology; EARTH SCIENCE; BIOLOGICAL CLASSIFICATION; ANIMALS/VERTEBRATES; MAMMALS; CARNIVORES; SEALS/SEA LIONS/WALRUSES; BIOSPHERE; ECOLOGICAL DYNAMICS; Arctic; Svalbard; Jan Mayen; Tusenøyane; North Atlantic; Odobenus rosmarus; walrus*
• Online Access: http://data.npolar.no/dataset/c23b313f-0909-5b83-9330-20b161df6008

Nine male walruses were equipped with dive recording devices in Svalbard to investigate walrus diving and haul-out behaviour in late summer 1991 and 1993. Dive information on 6,018 dives was collected by 3 satellite linked dive recorders. Additional dive information on 7,769 dives was obtained from 3 time depth recorders. Dives had to be deeper than 2 m to be recorded as dives. Dive duration and depth were recorded in 6 intervals each. Diving sessions were considered to start when a walrus left its haul-out site and started diving U-shaped dives deeper than 10 m. The diving period ended when the walrus hauled out again. Haul out was considered to be the period when the walrus was hauled out of the water, i.e. dry. If consecutive haul-out periods were separated by wet periods shorter than 15 min, then the consecutive haul-out periods, including the wet times, were grouped as one. The deepest dive recorded was 67 m, but mean depth of foraging dives was 22.5 m. The longest-lasting dive recorded was 24 min, but mean duration of foraging dives was 6 min. The walruses, on average, spent 56 h in the water followed by 20 h hauled out on land.