Article

FORAGING ECOLOGY OF NORTHERN ELEPHANT SEALS

B. J. Le Boeuf

Department of Biology and Institute of Marine Sciences, University of California, Santa Cruz, California 95064 USA

Search for more papers by this author
D. E. Crocker

Department of Biology and Institute of Marine Sciences, University of California, Santa Cruz, California 95064 USA

Search for more papers by this author
D. P. Costa

Department of Biology and Institute of Marine Sciences, University of California, Santa Cruz, California 95064 USA

Search for more papers by this author
S. B. Blackwell

Department of Biology and Institute of Marine Sciences, University of California, Santa Cruz, California 95064 USA

Search for more papers by this author
P. M. Webb

Department of Biology and Institute of Marine Sciences, University of California, Santa Cruz, California 95064 USA

Search for more papers by this author
D. S. Houser

Department of Biology and Institute of Marine Sciences, University of California, Santa Cruz, California 95064 USA

Search for more papers by this author
First published: 01 June 2000
Cited by: 175

Abstract

Sexual segregation in foraging is predicted from the great size disparity of male and female northern elephant seals, Mirounga angustirostris. Our aim was to test this prediction by measuring diving and foraging behavior, foraging locations, and distribution of the sexes during biannual migrations in the northeastern Pacific Ocean. Daily movements of 27 adult males and 20 adult females, during 56 migrations from Año Nuevo, California, USA, were determined by Argos satellite telemetry via head‐mounted platform transmitter terminals. Diving records were obtained with archival time–depth–speed recorders attached to the backs of seals that were recovered when the seals returned to the rookery. Pronounced sex differences were found in foraging location and foraging pattern, as reflected by horizontal transit speed and diving behavior. Males moved directly north or northwest at a mean speed of 90 ± 27 km/d to focal foraging areas along the continental margin ranging from coastal Oregon (534 km away) to the western Aleutian Islands (4775 km away). Males remained in these areas (mean size = 7892 km2) for 21–84% of their 4‐mo stays at sea. The predominance of flat‐bottom dives in these areas suggests concentrated feeding on benthic prey. Migration distance and estimated mass gain were positively correlated with male size, and individual males returned to the same area to forage on subsequent migrations. In contrast, females ranged across a wider area of the northeastern Pacific, from 38° to 60° N and from the coast to 172.5° E. Focal foraging areas, indicated by a reduction in swim speed to <0.4 m/s, were distributed over deep water along the migratory path, with females remaining on them a mean of 3.5 d before moving to another one. Jagged‐bottom dives that tracked the deep scattering layer prevailed in these areas, suggesting that females were feeding on pelagic prey in the water column. Females took roughly similar initial paths in subsequent migrations, but large deviations from the previous route were observed. We conclude that there is habitat segregation between the sexes. Females range widely over deep water, apparently foraging on patchily distributed, vertically migrating, pelagic prey, whereas males forage along the continental margin at the distal end of their migration in a manner consistent with feeding on benthic prey.

Number of times cited: 175

  • , An evaluation of three-dimensional photogrammetric and morphometric techniques for estimating volume and mass in Weddell seals Leptonychotes weddellii, PLOS ONE, 13, 1, (e0189865), (2018).
  • , Host characteristics and infection level of an intestinal parasite Corynosoma strumosum (Acanthocephala) in the Kuril harbor seal of Erimo Cape, Hokkaido, Japan, Parasitology International, 67, 2, (237), (2018).
  • , Climate mediates the success of migration strategies in a marine predator, Ecology Letters, 21, 1, (63-71), (2017).
  • , Distribution, Encyclopedia of Marine Mammals, 10.1016/B978-0-12-804327-1.00106-0, (259-262), (2018).
  • , Reproductive skipping as an optimal life history strategy in the southern elephant seal, Mirounga leonina, Ecology and Evolution, 8, 18, (9158-9170), (2018).
  • , Large‐scale molecular diet analysis in a generalist marine mammal reveals male preference for prey of conservation concern, Ecology and Evolution, 8, 19, (9889-9905), (2018).
  • , Oxygen minimum zone: An important oceanographic habitat for deep‐diving northern elephant seals, Mirounga angustirostris, Ecology and Evolution, 7, 16, (6259-6270), (2017).
  • , Searching for prey in a three‐dimensional environment: hierarchical movements enhance foraging success in northern elephant seals, Functional Ecology, 31, 2, (361-369), (2016).
  • , Adult male northern elephant seals maintain high rates of glucose production during extended breeding fasts, Journal of Comparative Physiology B, 187, 8, (1183), (2017).
  • , Evaluating gain functions in foraging bouts using vertical excursions in northern elephant seals, Animal Behaviour, 129, (15), (2017).
  • , Linking mesopelagic prey abundance and distribution to the foraging behavior of a deep-diving predator, the northern elephant seal, Deep Sea Research Part II: Topical Studies in Oceanography, 10.1016/j.dsr2.2016.11.007, 140, (163-170), (2017).
  • , Role of fecundity selection on the evolution of sexual size dimorphism in mammals, Animal Behaviour, 128, (1), (2017).
  • , “Bio‐logging” as a Tool to Study and Monitor Marine Ecosystems, or How to Spy on Sea Creatures, Tools for Oceanography and Ecosystemic Modeling, (143-173), (2016).
  • , Serum POP concentrations are highly predictive of inner blubber concentrations at two extremes of body condition in northern elephant seals, Environmental Pollution, 10.1016/j.envpol.2016.07.052, 218, (651-663), (2016).
  • , Evaluating Hair as a Predictor of Blood Mercury: The Influence of Ontogenetic Phase and Life History in Pinnipeds, Archives of Environmental Contamination and Toxicology, 10.1007/s00244-015-0174-3, 70, 1, (28-45), (2015).
  • , Mercury correlations among blood, muscle, and hair of northern elephant seals during the breeding and molting fasts, Environmental Toxicology and Chemistry, 35, 8, (2103-2110), (2016).
  • , The better to eat you with: the comparative feeding morphology of phocid seals (Pinnipedia, Phocidae), Journal of Anatomy, 228, 3, (396-413), (2015).
  • , Navigating uncertain waters: a critical review of inferring foraging behaviour from location and dive data in pinnipeds, Movement Ecology, 10.1186/s40462-016-0090-9, 4, 1, (2016).
  • , Sexual segregation when foraging in an extremely social killer whale population, Behavioral Ecology and Sociobiology, 10.1007/s00265-015-2038-2, 70, 1, (189-198), (2015).
  • , Foraging distribution overlap and marine reserve usage amongst sub-Antarctic predators inferred from a multi-species satellite tagging experiment, Ecological Indicators, 70, (531), (2016).
  • , An animal-borne active acoustic tag for minimally invasive behavioral response studies on marine mammals, Animal Biotelemetry, 4, 1, (2016).
  • , Stable Isotopes Reveal Long-Term Fidelity to Foraging Grounds in the Galapagos Sea Lion (Zalophus wollebaeki), PLOS ONE, 11, 1, (e0147857), (2016).
  • , Oxidative stress is a potential cost of breeding in male and female northern elephant seals, Functional Ecology, 29, 3, (367-376), (2014).
  • , Contrasting responses of male and female foraging effort to year‐round wind conditions, Journal of Animal Ecology, 84, 6, (1490-1496), (2015).
  • , Taking animal tracking to new depths: synthesizing horizontal–vertical movement relationships for four marine predators, Ecology, 96, 2, (417-427), (2015).
  • , Sexual segregation in a wide-ranging marine predator is a consequence of habitat selection, Marine Ecology Progress Series, 518, (1), (2015).
  • , Fine-scale whisker growth measurements can reveal temporal foraging patterns from stable isotope signatures, Marine Ecology Progress Series, 523, (243), (2015).
  • , Adipose Triglyceride Lipase, Not Hormone-Sensitive Lipase, Is the Primary Lipolytic Enzyme in Fasting Elephant Seals (Mirounga angustirostris), Physiological and Biochemical Zoology, 88, 3, (284), (2015).
  • , Summing the strokes: energy economy in northern elephant seals during large-scale foraging migrations, Movement Ecology, 3, 1, (2015).
  • , Flexible preference of southern elephant seals for distinct mesoscale features within the Antarctic Circumpolar Current, Progress in Oceanography, 10.1016/j.pocean.2014.11.011, 131, (46-58), (2015).
  • , Differences in dive behaviour among the world’s three narwhal Monodon monoceros populations correspond with dietary differences, Marine Ecology Progress Series, 10.3354/meps11202, 525, (273-285), (2015).
  • , Sexual foraging segregation in South American sea lions increases during the pre-breeding period in the Río de la Plata plume, Marine Ecology Progress Series, 525, (261), (2015).
  • , Are Vibrissae Viable Sensory Structures for Prey Capture in Northern Elephant Seals, irounga angustirostris?, The Anatomical Record, 298, 4, (750-760), (2014).
  • , Evaluation of Argos Telemetry Accuracy in the High-Arctic and Implications for the Estimation of Home-Range Size, PLOS ONE, 10, 11, (e0141999), (2015).
  • , Scale‐dependent foraging ecology of a marine top predator modelled using passive acoustic data, Functional Ecology, 28, 1, (206-217), (2013).
  • , Purine nucleoside phosphorylase and xanthine oxidase activities in erythrocytes and plasma from marine, semiaquatic and terrestrial mammals, Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 171, (31), (2014).
  • , Using short-term measures of behaviour to estimate long-term fitness of southern elephant seals, Marine Ecology Progress Series, 496, (99), (2014).
  • , Analysis of environmental correlates of sexual segregation in northern elephant seals using species distribution models, Marine Biology, 161, 2, (481), (2014).
  • , Variance in male reproductive success and sexual size dimorphism in pinnipeds: testing an assumption of sexual selection theory, Mammal Review, 44, 2, (88-93), (2013).
  • , Drift Diving by Hooded Seals (Cystophora cristata) in the Northwest Atlantic Ocean, PLoS ONE, 9, 7, (e103072), (2014).
  • , Lifetime foraging patterns of the wandering albatross: Life on the move!, Journal of Experimental Marine Biology and Ecology, 10.1016/j.jembe.2013.10.021, 450, (68-78), (2014).
  • , The foraging benefits of being fat in a highly migratory marine mammal, Proceedings of the Royal Society B: Biological Sciences, 281, 1797, (20142120), (2014).
  • , Combining individual animal movement and ancillary biotelemetry data to investigate population‐level activity budgets, Ecology, 94, 4, (838-849), (2013).
  • , Spatial and Social Sexual Segregation Patterns in Indo-Pacific Bottlenose Dolphins (Tursiops aduncus), PLoS ONE, 8, 1, (e52987), (2013).
  • , Effects of maternal age and mass on foraging behaviour and foraging success in the northern elephant seal, Functional Ecology, 27, 4, (1055-1063), (2013).
  • , Unravelling the mysteries of a mesopelagic diet: a large apex predator specializes on small prey, Functional Ecology, 27, 3, (710-717), (2013).
  • , Estimating resource acquisition and at‐sea body condition of a marine predator, Journal of Animal Ecology, 82, 6, (1300-1315), (2013).
  • , Error Properties of Argos Satellite Telemetry Locations Using Least Squares and Kalman Filtering, PLoS ONE, 8, 5, (e63051), (2013).
  • , Foraging habitats of southern elephant seals, Mirounga leonina, from the Northern Antarctic Peninsula, Deep Sea Research Part II: Topical Studies in Oceanography, 10.1016/j.dsr2.2012.07.009, 88-89, (47-60), (2013).
  • , Behavioral ecology of jumbo squid (Dosidicus gigas) in relation to oxygen minimum zones, Deep Sea Research Part II: Topical Studies in Oceanography, 95, (197), (2013).
  • , Pandemic H1N1 Influenza Isolated from Free-Ranging Northern Elephant Seals in 2010 off the Central California Coast, PLoS ONE, 8, 5, (e62259), (2013).
  • , A summary of the use of electronic tagging to provide insights into salmon migration and survival, Environmental Biology of Fishes, 96, 2-3, (419), (2013).
  • , Niche Divergence Among Sex and Age Classes in Black-and-White Snub-nosed Monkeys (Rhinopithecus bieti), International Journal of Primatology, 34, 5, (946), (2013).
  • , Mobile receivers: releasing the mooring to ‘see’ where fish go, Environmental Biology of Fishes, 96, 2-3, (189), (2013).
  • , Does location really matter? An inter-colony comparison of seabirds breeding at varying distances from productive oceanographic features in the Bering Sea, Deep Sea Research Part II: Topical Studies in Oceanography, 94, (178), (2013).
  • , Cumulative human impacts on marine predators, Nature Communications, 4, (2013).
  • , Size and seasonal influences on the foraging range of female grey seals in the northeast Atlantic, Marine Biology, 160, 3, (531), (2013).
  • , Long-Distance Animal Migrations in the Oceanic Environment: Orientation and Navigation Correlates, ISRN Zoology, 2013, (1), (2013).
  • , Beyond correlation: integrating environmentally and behaviourally mediated processes in models of marine mammal distributions, Endangered Species Research, 22, 3, (191), (2013).
  • , Moderating Argos location errors in animal tracking data, Methods in Ecology and Evolution, 3, 6, (999-1007), (2012).
  • , How are trace elements mobilized during the postweaning fast in Northern elephant seals?, Environmental Toxicology and Chemistry, 31, 10, (2354-2365), (2012).
  • , Benthic foraging on seamounts: A specialized foraging behavior in a deep‐diving pinniped, Marine Mammal Science, 28, 3, (E333-E344), (2011).
  • , Ontogenetic changes in feeding habits of northern elephant seals revealed by δ15N and δ13C analysis of growth layers in teeth, Marine Ecology Progress Series, 450, (229), (2012).
  • , The magnetic map of hatchling loggerhead sea turtles, Current Opinion in Neurobiology, 22, 2, (336), (2012).
  • , Foraging Behavior and Success of a Mesopelagic Predator in the Northeast Pacific Ocean: Insights from a Data-Rich Species, the Northern Elephant Seal, PLoS ONE, 7, 5, (e36728), (2012).
  • , Deep divers in even deeper seas: habitat use of male southern elephant seals from Marion Island, Antarctic Science, 10.1017/S0954102012000570, 24, 06, (561-570), (2012).
  • , Stable isotope analyses reveal individual variability in the trophic ecology of a top marine predator, the southern elephant seal, Oecologia, 169, 2, (395), (2012).
  • , The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review, Environmental Chemistry, 10.1071/EN11140, 9, 4, (321), (2012).
  • , Spatial Variation in Foraging Behaviour of a Marine Top Predator (Phoca vitulina) Determined by a Large-Scale Satellite Tagging Program, PLoS ONE, 7, 5, (e37216), (2012).
  • , Classifying area-restricted search (ARS) using a partial sum approach, Theoretical Ecology, 5, 3, (325), (2012).
  • , In situ measures of foraging success and prey encounter reveal marine habitat‐dependent search strategies, Ecology, 92, 6, (1258-1270), (2011).
  • , A Dispersive Migration in the Atlantic Puffin and Its Implications for Migratory Navigation, PLoS ONE, 6, 7, (e21336), (2011).
  • , Flexible foraging behaviour of a sexually dimorphic seabird: large males do not always dive deep, Marine Ecology Progress Series, 428, (271), (2011).
  • , High-density lipoprotein remains elevated despite reductions in total cholesterol in fasting adult male elephant seals (Mirounga angustirostris), Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 159, 4, (214), (2011).
  • , Development of foraging strategies with age in a long-lived marine predator, Marine Ecology Progress Series, 431, (267), (2011).
  • , Water column use and forage strategies of female southern elephant seals from Marion Island, Marine Biology, 10.1007/s00227-011-1719-2, 158, 9, (2125-2139), (2011).
  • , Robben-Forschung in Kalifornien, Biologie in unserer Zeit, 41, 3, (164), (2011).
  • , Electronic tracking tag programming is critical to data collection for behavioral time‐series analysis, Ecosphere, 2, 1, (1-12), (2011).
  • , Posture and body acceleration tracking by inertial and magnetic sensing: Application in behavioral analysis of free-ranging animals, Biomedical Signal Processing and Control, 6, 1, (94), (2011).
  • , Blood dynamics of mercury and selenium in northern elephant seals during the lactation period, Environmental Pollution, 10.1016/j.envpol.2011.06.019, 159, 10, (2523-2529), (2011).
  • , Pitching a new angle on elephant seal dive patterns, Polar Biology, 34, 8, (1197), (2011).
  • , Assessing accuracy and utility of satellite-tracking data using Argos-linked Fastloc-GPS, Animal Behaviour, 80, 3, (571), (2010).
  • , Using stable isotope biogeochemistry to study marine mammal ecology, Marine Mammal Science, 26, 3, (509-572), (2010).
  • , Looking at the unseen: combining animal bio‐logging and stable isotopes to reveal a shift in the ecological niche of a deep diving predator, Ecography, 33, 4, (709-719), (2010).
  • , A View of the Ocean from Pacific Predators, Life in the World's Oceans, (291-311), (2010).
  • , Linking foraging behaviour to physical oceanographic structures: Southern elephant seals and mesoscale eddies east of Kerguelen Islands, Progress in Oceanography, 10.1016/j.pocean.2010.09.025, 87, 1-4, (61-71), (2010).
  • , A lifetime at depth: vertical distribution of southern elephant seals in the water column, Polar Biology, 33, 8, (1037), (2010).
  • , Approaches to Studying Climatic Change and its Role on the Habitat Selection of Antarctic Pinnipeds, Integrative and Comparative Biology, 50, 6, (1018), (2010).
  • , Measurements of foraging success in a highly pelagic marine predator, the northern elephant seal, Journal of Animal Ecology, 79, 6, (1146-1156), (2010).
  • , Many routes lead to Rome: potential causes for the multi‐route migration system of Red Knots, Calidris canutus islandica, Ecology, 91, 6, (1822-1831), (2010).
  • , Seals map bathymetry of the Antarctic continental shelf, Geophysical Research Letters, 37, 21, (2010).
  • , Habitat use of a multispecific seagrass meadow by green turtles Chelonia mydas at Mayotte Island, Marine Biology, 157, 12, (2581), (2010).
  • , Alimentary niche partitioning in the Galapagos sea lion, Zalophus wollebaeki, Marine Biology, 10.1007/s00227-010-1535-0, 157, 12, (2769-2781), (2010).
  • , Habitat and behaviour of yellowfin tuna Thunnus albacares in the Gulf of Mexico determined using pop‐up satellite archival tags, Journal of Fish Biology, 74, 7, (1434-1449), (2009).
  • , Ontogenic dietary changes in South American sea lions, Journal of Zoology, 279, 3, (251-261), (2009).
  • , Time to eat: measurements of feeding behaviour in a large marine predator, the northern elephant seal Mirounga angustirostris, Journal of Animal Ecology, 78, 3, (513-523), (2008).
  • , Adult male southern elephant seals from King George Island utilize the Weddell Sea, Antarctic Science, 21, 02, (113), (2009).
  • , Reproductive Behavior, Encyclopedia of Marine Mammals, 10.1016/B978-0-12-373553-9.00217-0, (943-955), (2009).
  • , Sex-specific, seasonal foraging tactics of adult grey seals (Halichoerus grypus) revealed by state–space analysis, Ecology, 90, 11, (3209), (2009).
  • , North Pacific Climate Mediates Offspring Sex Ratio in Northern Elephant Seals, Journal of Mammalogy, 10.1644/08-MAMM-A-130.1, 90, 1, (1-8), (2009).
  • , Development of foraging behavior in juvenile northern elephant seals, Journal of Zoology, 274, 2, (180-187), (2007).
  • , Dive and beak movement patterns in leatherback turtles Dermochelys coriacea during internesting intervals in French Guiana, Journal of Animal Ecology, 77, 2, (236-246), (2008).
  • , Sea turtles: A review of some key recent discoveries and remaining questions, Journal of Experimental Marine Biology and Ecology, 356, 1-2, (1), (2008).
  • , Upper ocean variability in west Antarctic Peninsula continental shelf waters as measured using instrumented seals, Deep Sea Research Part II: Topical Studies in Oceanography, 10.1016/j.dsr2.2007.11.003, 55, 3-4, (323-337), (2008).
  • 2008 IEEE/ION Position, Location and Navigation Symposium Monterey, CA, USA 2008 IEEE/ION Position, Location and Navigation Symposium IEEE , (2008). 978-1-4244-1536-6 978-1-4244-1537-3 Initial results from an in-situ environmental monitoring marine mammal tag , (2008). 912 922 4570033 , 10.1109/PLANS.2008.4570033 http://ieeexplore.ieee.org/document/4570033/
  • , Shallow food for deep divers: Dynamic foraging behavior of male sperm whales in a high latitude habitat, Journal of Experimental Marine Biology and Ecology, 354, 1, (119), (2008).
  • , Chapter 2 Sexual Segregation in Marine Fish, Reptiles, Birds and Mammals, , 10.1016/S0065-2881(08)00002-3, (107-170), (2008).
  • , Contaminants still high in top-level carnivores in the Southern California Bight: Levels of DDT and PCBs in resident and transient pinnipeds, Marine Pollution Bulletin, 56, 12, (1973), (2008).
  • , A validated approach for supervised dive classification in diving vertebrates, Journal of Experimental Marine Biology and Ecology, 363, 1-2, (75), (2008).
  • , ESTIMATING POPULATION SIZE IN ASYNCHRONOUS AGGREGATIONS: A BAYESIAN APPROACH AND TEST WITH ELEPHANT SEAL CENSUSES, Marine Mammal Science, 23, 4, (834-855), (2007).
  • , Sex differences in grey seal diet reflect seasonal variation in foraging behaviour and reproductive expenditure: evidence from quantitative fatty acid signature analysis, Journal of Animal Ecology, 76, 3, (490-502), (2007).
  • , How can we observe the underwater feeding behavior of endotherms?, Polar Science, 1, 2-4, (101), (2007).
  • , Swimming speed and foraging strategies of northern elephant seals, Deep Sea Research Part II: Topical Studies in Oceanography, 54, 3-4, (369), (2007).
  • , Bottom or midwater: alternative foraging behaviours in adult female loggerhead sea turtles, Journal of Zoology, 273, 1, (46-55), (2007).
  • , Radio-tracking squirrels: Performance of home range density and linkage estimators with small range and sample size, Ecological Modelling, 202, 3-4, (333), (2007).
  • , A comparison of indirect measures of feeding behaviour based on ARGOS tracking data, Deep Sea Research Part II: Topical Studies in Oceanography, 54, 3-4, (356), (2007).
  • , Erratic continental rocks on volcanic seamounts off the US west coast, Marine Geology, 10.1016/j.margeo.2007.07.007, 246, 1, (1-8), (2007).
  • , The cost of success: reproductive effort in male southern elephant seals (Mirounga leonina), Behavioral Ecology and Sociobiology, 62, 2, (159), (2007).
  • , Deep divers in shallow seas: Southern elephant seals on the Patagonian shelf, Deep Sea Research Part I: Oceanographic Research Papers, 10.1016/j.dsr.2007.06.006, 54, 10, (1792-1814), (2007).
  • , Age-related shifts in the diet composition of southern elephant seals expand overall foraging niche, Marine Biology, 10.1007/s00227-006-0417-y, 150, 6, (1441-1452), (2006).
  • , Locomotion in diving elephant seals: physical and physiological constraints, Philosophical Transactions of the Royal Society B: Biological Sciences, 362, 1487, (2141), (2007).
  • , DIFFERENCES IN FORAGING LOCATION OF MEXICAN AND CALIFORNIA ELEPHANT SEALS: EVIDENCE FROM STABLE ISOTOPES IN PUPS, Marine Mammal Science, 22, 2, (326-338), (2006).
  • , A Method for Modeling Marine Mammal Movement and Behavior for Environmental Impact Assessment, IEEE Journal of Oceanic Engineering, 31, 1, (76), (2006).
  • 2006 IEEE/ION Position, Location, And Navigation Symposium Coronado, CA April 25-27, 2006 2006 IEEE/ION Position, Location, And Navigation Symposium IEEE , (2006). 0-7803-9454-2 Marine Mammal Marker (MAMMARK) Dead Reckoning Sensor for In-Situ Environmental Monitoring 976 987 , 10.1109/PLANS.2006.1650699 http://ieeexplore.ieee.org/document/1650699/
  • , Individual variation in feeding habitat use by adult female green sea turtles (Chelonia mydas): are they obligately neritic herbivores?, Oecologia, 149, 1, (52), (2006).
  • , Robust hierarchical state–space models reveal diel variation in travel rates of migrating leatherback turtles, Journal of Animal Ecology, 75, 5, (1046-1057), (2006).
  • , Stomach temperature telemetry reveals temporal patterns of foraging success in a free‐ranging marine mammal, Journal of Animal Ecology, 75, 2, (408-420), (2006).
  • , Marine animal behaviour: neglecting ocean currents can lead us up the wrong track, Proceedings of the Royal Society B: Biological Sciences, 10.1098/rspb.2006.3623, 273, 1602, (2697-2702), (2006).
  • , Environmental controls on food web regimes: A fluvial perspective, Progress in Oceanography, 68, 2-4, (125), (2006).
  • , Distribution of the Steller sea lion Eumetopias jubatus during winter in the northern Sea of Japan, along the west coast of Hokkaido, based on aerial and land sighting surveys, Fisheries Science, 72, 5, (922), (2006).
  • , A comparative analysis of animals' understanding of the human pointing gesture, Animal Cognition, 9, 2, (81), (2006).
  • , Persistence of forage fish ‘hot spots’ and its association with foraging Steller sea lions (Eumetopias jubatus) in southeast Alaska, Deep Sea Research Part II: Topical Studies in Oceanography, 53, 3-4, (432), (2006).
  • , Segregation of Beaufort Sea beluga whales during the open-water season, Canadian Journal of Zoology, 10.1139/z06-160, 84, 12, (1743-1751), (2006).
  • , Southern elephant seal trajectories, fronts and eddies in the Brazil/Malvinas Confluence, Deep Sea Research Part I: Oceanographic Research Papers, 10.1016/j.dsr.2006.08.015, 53, 12, (1907-1924), (2006).
  • , The effects of castration, sex ratio and population density on social segregation and habitat use in Soay sheep, Behavioral Ecology and Sociobiology, 59, 5, (694), (2006).
  • , Sexual segregation of seasonal foraging habitats in a non-migratory marine mammal, Proceedings of the Royal Society B: Biological Sciences, 273, 1599, (2319), (2006).
  • , Phenotypically Linked Dichotomy in Sea Turtle Foraging Requires Multiple Conservation Approaches, Current Biology, 16, 10, (990), (2006).
  • , RANGE AND MOVEMENTS OF FEMALE HEAVISIDE'S DOLPHINS (CEPHALORHYNCHUS HEAVISIDII), AS DETERMINED BY SATELLITE-LINKED TELEMETRY, Journal of Mammalogy, 87, 5, (866), (2006).
  • , Polychlorinated biphenyls, dioxins, and furans in weaned, free‐ranging northern elephant seal pups from central California, USA, Environmental Toxicology and Chemistry, 24, 3, (629-633), (2009).
  • , Males in the shade: habitat use and sexual segregation in the Galápagos sea lion (Zalophus californianus wollebaeki), Behavioral Ecology and Sociobiology, 59, 2, (293), (2005).
  • , Drift dives by male New Zealand fur seals (Arctocephalus forsteri), Canadian Journal of Zoology, 83, 2, (293), (2005).
  • , Blubber fatty acids of gray seals reveal sex differences in the diet of a size-dimorphic marine carnivore, Canadian Journal of Zoology, 83, 3, (377), (2005).
  • , Behaviour of leatherback sea turtles, Dermochelys coriacea, during the migratory cycle, Proceedings of the Royal Society B: Biological Sciences, 272, 1572, (1547), (2005).
  • , Intraspecific variation in movement patterns: modeling individual behaviour in a large marine predator, Oikos, 105, 1, (15-30), (2004).
  • , Using satellite telemetry and aerial counts to estimate space use by grey seals around the British Isles, Journal of Applied Ecology, 41, 3, (476-491), (2004).
  • , Regional differences in diving behavior of harbor seals in the Gulf of Alaska, Canadian Journal of Zoology, 82, 11, (1755), (2004).
  • , First records of oceanic dive profiles for leatherback turtles, Dermochelys coriacea, indicate behavioural plasticity associated with long-distance migration, Animal Behaviour, 67, 4, (733), (2004).
  • , Loyalty pays: potential life history consequences of fidelity to marine foraging regions by southern elephant seals, Animal Behaviour, 10.1016/j.anbehav.2003.12.013, 68, 6, (1349-1360), (2004).
  • , Separation of foraging habitat among breeding sites of a colonial marine predator, the northern fur seal (Callorhinus ursinus), Canadian Journal of Zoology, 82, 1, (20), (2004).
  • , Dispersal of female southern elephant seals and their prey consumption during the austral summer: relevance to management and oceanographic zones, Journal of Applied Ecology, 40, 4, (703-715), (2003).
  • , A THREE‐STAGE ALGORITHM FOR FILTERING ERRONEOUS ARGOS SATELLITE LOCATIONS, Marine Mammal Science, 19, 2, (371-383), (2006).
  • , Sex differences in the seasonal patterns of energy storage and expenditure in a phocid seal, Journal of Animal Ecology, 72, 2, (280-291), (2003).
  • , Sex differences in diving at multiple temporal scales in a size‐dimorphic capital breeder, Journal of Animal Ecology, 72, 6, (979-993), (2003).
  • , Vertical stratification of fatty acids in the blubber of southern elephant seals (Mirounga leonina): implications for diet analysis, Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 134, 2, (253), (2003).
  • , Sex differences in the diving behaviour of a size-dimorphic capital breeder: the grey seal, Animal Behaviour, 10.1006/anbe.2003.2284, 66, 4, (777-789), (2003).
  • , The effect of a low-frequency sound source (acoustic thermometry of the ocean climate) on the diving behavior of juvenile northern elephant seals,Mirounga angustirostris, The Journal of the Acoustical Society of America, 113, 2, (1155), (2003).
  • , Movements and foraging areas of naïve, recently weaned southern elephant seal pups, Journal of Animal Ecology, 71, 1, (65-78), (2002).
  • , HOW OFTEN DO FISHES “RUN ON EMPTY”?, Ecology, 83, 8, (2145-2151), (2002).
  • , AN ALGORITHM TO IMPROVE GEOLOCATION POSITIONS USING SEA SURFACE TEMPERATURE AND DIVING DEPTH, Marine Mammal Science, 18, 4, (940-951), (2006).
  • , Revealing pelagic habitat use: the tagging of Pacific pelagics program, Oceanologica Acta, 25, 5, (255), (2002).
  • , Dive shapes reveal temporal changes in the foraging behaviour of different age and sex classes of harbour seals (Phoca vitulina), Canadian Journal of Zoology, 80, 9, (1569), (2002).
  • , Diving Physiology of Marine Vertebrates, eLS, (2007).
  • , Marine Mammal Migrations and Movement Patterns, Encyclopedia of Ocean Sciences, 10.1016/B978-012374473-9.00442-2, (596-604), (2001).
  • , MOVEMENTS OF SATELLITE‐TAGGED SUBADULT AND ADULT HARBOR SEALS IN PRINCE WILLIAM SOUND, ALASKA, Marine Mammal Science, 17, 4, (835-861), (2006).
  • , Tagging and Tracking, CRC Handbook of Marine Mammal Medicine, 10.1201/9781420041637.ch38, (851-880), (2009).
  • , Marine Mammal Migrations and Movement Patterns, Encyclopedia of Ocean Sciences, 10.1006/rwos.2001.0442, (1603-1611), (2001).
  • , Three-dimensional movements and swimming activity of a northern elephant seal, Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 129, 4, (759), (2001).
  • , Autonomous Pinniped Environmental Samplers: Using Instrumented Animals as Oceanographic Data Collectors, Journal of Atmospheric and Oceanic Technology, 18, 11, (1882), (2001).
  • , Effects of Age, Adipose Percent, and Reproduction on PCB Concentrations and Profiles in an Extreme Fasting North Pacific Marine Mammal, PLoS ONE, 10.1371/journal.pone.0096191, 9, 4, (e96191), (2014).
  • , Animal-Borne Acoustic Transceivers Reveal Patterns of at-Sea Associations in an Upper-Trophic Level Predator, PLoS ONE, 10.1371/journal.pone.0048962, 7, 11, (e48962), (2012).
  • , Options for modulating intra-specific competition in colonial pinnipeds: the case of harbour seals ( Phoca vitulina ) in the Wadden Sea , PeerJ, 10.7717/peerj.957, 3, (e957), (2015).
  • , Ontogenetic changes in skeletal muscle fiber type, fiber diameter and myoglobin concentration in the Northern elephant seal (Mirounga angustirostris), Frontiers in Physiology, 10.3389/fphys.2014.00217, 5, (2014).
  • , A Parsimonious Approach to Modeling Animal Movement Data, PLoS ONE, 10.1371/journal.pone.0004711, 4, 3, (e4711), (2009).
  • , Investigating Annual Diving Behaviour by Hooded Seals (Cystophora cristata) within the Northwest Atlantic Ocean, PLoS ONE, 10.1371/journal.pone.0080438, 8, 11, (e80438), (2013).
  • , The Sun, Moon, Wind, and Biological Imperative–Shaping Contrasting Wintertime Migration and Foraging Strategies of Adult Male and Female Northern Fur Seals (Callorhinus ursinus), PLoS ONE, 10.1371/journal.pone.0093068, 9, 4, (e93068), (2014).