Recent Submissions

  • Polar Bear Diets and Arctic Marine Food Webs: Insights from Fatty Acid Analysis 

    Thiemann, Gregory W., Sara J. Iverson, and Ian Stirling. 2008. "Polar Bear Diets and Arctic Marine Food Webs: Insights from Fatty Acid Analysis." Ecological Monographs 78(4): 591-613. Copyright by the Ecological Society of America
    We used quantitative fatty acid signature analysis (QFASA) to examine the diets of 1738 individual polar bears (Ursus maritimus) sampled across the Canadian Arctic over a 30-year span. Polar bear foraging varied over ...
  • Weaning mass affects changes in body composition and food intake in harbour seal pups during the first month of independence 

    Muelbert, MMC, WD Bowen, and SJ Iverson. 2003. "Weaning mass affects changes in body composition and food intake in harbour seal pups during the first month of independence." Physiological and Biochemical Zoology 76(3): 418-427. Copyright © 2003 The University of Chicago Press.
    In phocid seals, the transition to nutritional independence is abrupt, with females abandoning their offspring after weaning and returning to sea. We hypothesized that body size at weaning may play an important role in ...
  • Development of the blood and muscle oxygen stores in gray seals (Halichoerus grypus): Implications for juvenile diving capacity and the necessity of a terrestrial postweaning fast 

    Noren, SR, SJ Iverson, and DJ Boness. 2005. "Development of the blood and muscle oxygen stores in gray seals (Halichoerus grypus): Implications for juvenile diving capacity and the necessity of a terrestrial postweaning fast." Physiological and Biochemical Zoology 78(4): 482-490. Copyright © 2005 The University of Chicago Press.
    To successfully transition from nursing to foraging, phocid seal pups must develop adequate diving physiology within the limited time between birth and their first independent foraging trip to sea. We studied the postpartum ...
  • Body condition at weaning affects the duration of the postweaning fast in gray seal pups (Halichoerus grypus) 

    Noren, Shawn R., Daryl J. Boness, Sara J. Iverson, Jim McMillan, et al. 2008. "Body condition at weaning affects the duration of the postweaning fast in gray seal pups (Halichoerus grypus)." Physiological and Biochemical Zoology 81(3): 269-277. Copyright © 2008 The University of Chicago Press.
    Gray seals (Halichoerus grypus) undergo a terrestrial postweaning fast (PWF) that depletes energy reserves acquired during the suckling interval. Plasticity in PWF duration may ensure that pups of variable body condition ...
  • Seasonal changes in buoyancy and diving behaviour of adult grey seals 

    Beck, Carrie A., W. Don Bowen, and Sara J. Iverson. 2000. "Seasonal changes in buoyancy and diving behaviour of adult grey seals." Journal of Experimental Biology 203(15): 2323-2330.
    Phocid seals go through dramatic seasonal changes in body mass and composition as a result of the spatial and temporal separation of foraging, reproduction and moulting. These changes in body fat content and body mass ...
  • Repeatability in lactation performance and the consequences for maternal reproductive success in gray seals 

    Lang, S. L. C., S. J. Iverson, and W. D. Bowen. 2009. "Repeatability in lactation performance and the consequences for maternal reproductive success in gray seals." Ecology 90(9): 2513-2523. Copyright by the Ecological Society of America.
    In mammals, the most significant maternal effect on offspring growth during lactation is the ability of females to efficiently transfer milk energy to their neonates. However, despite the importance of the transfer of ...
  • Variation in milk production and lactation performance in grey seals and consequences for pup growth and weaning characteristics 

    Mellish, JAE, SJ Iverson, and WD Bowen. 1999. "Variation in milk production and lactation performance in grey seals and consequences for pup growth and weaning characteristics." Physiological and Biochemical Zoology 72(6): 677-690. Copyright © 1999 The University of Chicago Press.
    Phocid seals are one of the few groups of mammals capable of sustaining the energetic demands of lactation entirely through body nutrient stores while fasting. Lactation performance of the female in turn influences the ...
  • Animal-Borne Acoustic Transceivers Reveal Patterns of at-Sea Associations in an Upper-Trophic Level Predator 

    Lidgard, Damian C., W. Don Bowen, Ian D. Jonsen, and Sara J. Iverson. 2012. "Animal-Borne Acoustic Transceivers Reveal Patterns of at-Sea Associations in an Upper-Trophic Level Predator." Plos One 7(11): 48962-e48962.
    Satellite telemetry data have substantially increased our understanding of habitat use and foraging behaviour of upper-trophic marine predators, but fall short of providing an understanding of their social behaviour. We ...
  • Primiparous and multiparous females differ in mammary gland alveolar development: implications for milk production 

    Lang, Shelley L. C., Sara J. Iverson, and W. Don Bowen. 2012. "Primiparous and multiparous females differ in mammary gland alveolar development: implications for milk production." Journal of Experimental Biology 215(16): 2904-2911.
    Mammary gland capacity is influenced by the number of secretory cells in the gland, the activity of those cells and the size and arrangement of the alveoli that they form. Although reproductive experience has been shown ...
  • The Influence of Reproductive Experience on Milk Energy Output and Lactation Performance in the Grey Seal (Halichoerus grypus) 

    Lang, Shelley L. C., Sara J. Iverson, and W. Don Bowen. 2011. "The Influence of Reproductive Experience on Milk Energy Output and Lactation Performance in the Grey Seal (Halichoerus grypus)." Plos One 6(5): 19487-e19487.
    Although evidence from domestic and laboratory species suggests that reproductive experience plays a critical role in the development of aspects of lactation performance, whether reproductive experience may have a significant ...
  • Effect of a low-fat diet on body composition and blubber fatty acids of captive juvenile harp seals (Phoca groenlandica) 

    Kirsch, PE, SJ Iverson, and WD Bowen. 2000. "Effect of a low-fat diet on body composition and blubber fatty acids of captive juvenile harp seals (Phoca groenlandica)." Physiological and Biochemical Zoology 73(1): 45-59. Copyright © 2000 The University of Chicago Press.
    We investigated the effects of a change from a high-fat diet to a low-fat diet of differing fatty acid (FA) composition on the body composition and blubber FA of five captive juvenile harp seals. Seals that had been ...
  • Jellyfish Support High Energy Intake of Leatherback Sea Turtles (Dermochelys coriacea): Video Evidence from Animal-Borne Cameras 

    Heaslip, Susan G., Sara J. Iverson, W. Don Bowen, and Michael C. James. 2012. "Jellyfish Support High Energy Intake of Leatherback Sea Turtles (Dermochelys coriacea): Video Evidence from Animal-Borne Cameras." Plos One 7(3): 33259-e33259.
    The endangered leatherback turtle is a large, highly migratory marine predator that inexplicably relies upon a diet of low-energy gelatinous zooplankton. The location of these prey may be predictable at large oceanographic ...
  • Metabolism of dietary cetoleic acid (22 : 1n-11) in mink (Mustela vison) and gray seals (Halichoerus grypus) studied using radiolabeled fatty acids 

    Cooper, Margaret H., Sara J. Iverson, and Kirsti Rouvinen-Watt. 2006. "Metabolism of dietary cetoleic acid (22 : 1n-11) in mink (Mustela vison) and gray seals (Halichoerus grypus) studied using radiolabeled fatty acids." Physiological and Biochemical Zoology 79(4): 820-829. Copyright © 2006 The University of Chicago Press.
    Cetoleic acid (22:1n-11) is a good indicator of diet in marine predators and has proven to be an important fatty acid (FA) when using adipose tissue FA composition to study diet in marine mammals and seabirds. Feeding ...
  • Interspecific and intraspecific variation in proximate, mineral, and fatty acid composition of milk in old world fruit bats (Chiroptera : Pteropodidae) 

    Hood, WR, TH Kunz, OT Oftedal, SJ Iverson, et al. 2001. "Interspecific and intraspecific variation in proximate, mineral, and fatty acid composition of milk in old world fruit bats (Chiroptera : Pteropodidae)." Physiological and Biochemical Zoology 74(1): 134-146. Copyright © 2001 The University of Chicago Press.
    We examine the effect of body mass on milk composition among Old World fruit bats, including Pteropus pumilus (0.175 kg), Pteropus rodricensus (0.265 kg), Pteropus hypomelanus (0.571 kg), and Pteropus vampyrus (1.133 ...
  • Quantitative fatty acid signature analysis: A new method of estimating predator diets 

    Iverson, Sara J., Chris Field, W. Don Bowen, and Wade Blanchard. 2004. "Quantitative fatty acid signature analysis: A new method of estimating predator diets." Ecological Monographs 74(2): 211-235. Copyright by the Ecological Society of America
    Accurate estimates of the diets of predators are required in many areas of ecology, but for many species current methods are imprecise, limited to the last meal, and often biased. The diversity of fatty acids and their ...
  • The energetics of male reproduction in an acquatically mating pinniped, the harbour seal 

    Coltman, DW, WD Bowen, SJ Iverson, and DJ Boness. 1998. "The energetics of male reproduction in an acquatically mating pinniped, the harbour seal." Physiological zoology 71(4): 387-399. Copyright © 2005 The University of Chicago Press.
    The energy expenditure of breeding male harbour seals, Phoca vitulina, on Sable Island, Nova Scotia, was investigated by measuring changes in body mass, body composition, and water flux using isotope dilution. Seals lost ...
  • Linking movement, diving, and habitat to foraging success in a large marine predator 

    Austin, Deborah, W. Don Bowen, Jim I. McMillan, and Sara J. Iverson. 2006. "Linking movement, diving, and habitat to foraging success in a large marine predator." Ecology 87(12): 3095-3108. Copyright by the Ecological Society of America.
    Establishing where and when predators forage is essential to understanding trophic interactions, yet foraging behavior remains poorly understood in large marine carnivores. We investigated the factors leading to foraging ...
  • Demonstration of the deposition and modification of dietary fatty acids in pinniped blubber using radiolabelled precursors 

    Budge, SM, MH Cooper, and SJ Iverson. 2004. "Demonstration of the deposition and modification of dietary fatty acids in pinniped blubber using radiolabelled precursors." Physiological and Biochemical Zoology 77(4): 682-687. Copyright © 2004 The University of Chicago Press.
    Radioisotopes are commonly used to study the in vivo metabolism and deposition of dietary fatty acids in adipose tissue. The application of this approach to pinnipeds is problematic because of their large mass and blubber ...
  • Estimation of total body water in pinnipeds using hydrogen-isotope dilution 

    Bowen, WD, and SJ Iverson. 1998. "Estimation of total body water in pinnipeds using hydrogen-isotope dilution." Physiological zoology 71(3): 329-332. Copyright © 1998 The University of Chicago Press.
    No abstract available.