title: Counting calories in cormorants: dynamic body acceleration predicts daily energy expenditure measured in pelagic cormorants.
abstract: The integral of the dynamic component of acceleration over time has been proposed as a measure of energy expenditure in wild animals. We tested that idea by attaching accelerometers to the tails of free-ranging pelagic cormorants (Phalacrocorax pelagicus) and simultaneously estimating energy expenditure using doubly labelled water. Two different formulations of dynamic body acceleration, [vectorial and overall DBA (VeDBA and ODBA)], correlated with mass-specific energy expenditure (both R(2)=0.91). VeDBA models combining and separately parameterizing flying, diving, activity on land and surface swimming were consistently considered more parsimonious than time budget models and showed less variability in model fit. Additionally, we observed evidence for the presence of hypometabolic processes (i.e. reduced heart rate and body temperature; shunting of blood away from non-essential organs) that suppressed metabolism in cormorants while diving, which was the most metabolically important activity. We concluded that a combination of VeDBA and physiological processes accurately measured energy expenditure for cormorants.
authors.affiliation: Department of Integrative Biology, University of Guelph, Guelph, Canada N1G 2K8 mstothar@mail.uoguelph.ca.
authors.forename: Mason R
authors.identifier: 0000-0002-2863-908X
authors.initials: MR
authors.lastname: Stothart
authors.affiliation: Department of Natural Resource Sciences, McGill University, St. Anne de Bellevue, Quebec, Canada H9X 3V9.
authors.forename: Kyle H
authors.initials: KH
authors.lastname: Elliott
authors.affiliation: Department of Biology, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wood
authors.affiliation: Institute for Seabird Research and Conservation, Anchorage, AK 99516-9951, USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Hatch
authors.affiliation: Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, Scotland AB24 2TZ, UK State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China.
authors.forename: John R
authors.initials: JR
authors.lastname: Speakman
mesh_terms: D000054:Acceleration; D000413:Alaska; D000818:Animals; D001717:Birds / Q000502:physiology*; D001835:Body Weight; D003903:Deuterium; D017753:Ecosystem; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D062312:Islands; D008297:Male; D010103:Oxygen Isotopes; D014867:Water / Q000737:chemistry
chemical_list: D010103:Oxygen Isotopes; D014867:Water; D003903:Deuterium
keywords: Accelerometry; Doubly labelled water; Field metabolic rate