Accelerometers can measure total and activity-specific energy expenditures in free-ranging marine mammals only if linked to time-activity budgets

• Published in: Functional Ecology
• Main Authors: Jeanniard-Du-Dot, Tiphaine, Guinet, Christophe, Arnould, John P.Y., Speakman, John R, Trites, Andrew W.
• Other Authors: Fisheries Centre (Marine Mammal Research Unit), University of British Columbia (UBC), Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Institut National de la Recherche Agronomique (INRA)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), School of Life and Environmental Sciences, Deakin University Burwood, Institute of Biological and Environmental Sciences, University of Aberdeen, Marine Mammal Research Unit (University of British Columbia)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: acceleration; Antarctic fur seal; energy expenditure; foraging; metabolic rate; northern fur seal; time-activity budget; VeDBA; [SDE]Environmental Sciences; Antarctic; Antarc*; Antarctic Fur Seal; Arctocephalus gazella; Callorhinus ursinus; Northern fur seal
• Online Access: https://hal.science/hal-01507594; https://doi.org/10.1111/1365-2435.12729

International audience 1. Energy expenditure is an important component of foraging ecology, but is extremely difficultto estimate in free-ranging animals and depends on how animals partition their timebetween different activities during foraging. Acceleration data have emerged as a new way todetermine energy expenditure at a fine scale but this needs to be tested and validated in wildanimals.2. This study investigated whether vectorial dynamic body acceleration (VeDBA) could accuratelypredict the energy expended by marine predators during a full foraging trip. We alsoaimed to determine whether the accuracy of predictions of energy expenditure derived fromacceleration increased when partitioned by different types of at-sea activities (i.e. diving, transiting,resting and surface activities).3. To do so, we equipped 20 lactating northern (Callorhinus ursinus) and 20 lactating Antarcticfur seals (Arctocephalus gazella) with GPS, time-depth recorders and tri-axial accelerometersand obtained estimates of field metabolic rates using the doubly labelled water (DLW)method. VeDBA was derived from tri-axial acceleration, and at-sea activities (diving, transiting,resting and surface activities) were determined using dive depth, tri-axial acceleration andtravelling speed.4. We found that VeDBA did not accurately predict the total energy expended by fur sealsduring their full foraging trips (R2 = 036). However, the accuracy of VeDBA as a predictorof total energy expenditure increased significantly when foraging trips were partitioned byactivity and when activity-specific VeDBA was paired with time-activity budgets (R2 = 070).Activity-specific VeDBA also accurately predicted the energy expenditures of each activityindependent of each other (R2 > 085).5. Our study confirms that acceleration is a promising way to estimate energy expenditures offree-ranging marine mammals at a fine scale never attained before. However, it shows that itneeds to be based on the time-activity budgets that make up foraging trips rather than ...