Meeting Abstract
13.9 Friday, Jan. 4 Body Condition and Caloric Demand of Female Pacific Walruses (Odobenus rosmarus divergens) NOREN, SR*; TRIGGS, L; OLAND, L; PASCHKE, J; KRAMER, AW; UDEVITZ, MS; JAY, CV; University of California, Santa Cruz; Point Defiance Zoo and Aquarium; Indianapolis Zoo; Six Flags Discovery Kingdom; U.S. Geological Survey; U.S. Geological Survery snoren@biology.ucsc.edu
With declining sea ice availability, walruses are increasing their use of terrestrial haul-outs, which could deplete localized prey resources. Estimates of caloric demand and techniques for monitoring body condition are required for assessing the potential for population level effects on walruses. Caloric intake and body condition (length, girth, mass, and blubber thicknesses) were measured monthly over one year from non-reproductive female walruses housed at Indianapolis Zoo (n = 1; Tair = 18.7 ± 14ºC, Twater = 12.2 ± 0.1ºC), Six Flags Discovery Kingdom (n = 2; Tair = 19.6 ± 6 ºC, Twater = 13.9 ± 4.5ºC), and Point Defiance Zoo and Aquarium (n = 2; Tair = 13.8 ± 7ºC, Twater = 10 ± 2ºC). These individuals had an average (±SD) annual body mass of 683 ± 11 kg, 747 ± 14 kg, 764 ± 28 kg, 716 ± 28 kg, and 936 ± 27 kg comprised of 24 ± 2%, 26 ± 2%, 27 ± 2%, 27 ± 1%, and 30 ± 1% blubber, respectively. These body conditions were maintained with an average of 31,249 ± 4,449 kcal dy-1, 25,847 ± 4,100 kcal dy-1, 20,123 ± 4,247 kcal dy-1, 23,062 ± 5,448 kcal dy-1, and 29,403 ± 4,474 kcal dy-1. Based on our published bioenergetics model, these caloric intakes represent 61%, 47%, 35%, 45%, and 48% of those required by wild non-reproductive female walruses of equivalent body size. Much of this discrepancy is likely due to differences in activity level between captive and wild animals, as our bioenergetics model assumed that animals are active 83% of the time. Nonetheless, the basic physiology measured from animals in human care provides bounds on parameters used in bioenergetic models and serves as a basis for developing criteria for assessing body condition of wild walruses.
