Accelerometers can measure total and activity-specific energy expenditures in free-ranging marine mammals only if linked to time-activity budgets
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 todetermi...
Published in: | Functional Ecology |
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Main Authors: | , , , , |
Other Authors: | , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2017
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Subjects: | |
Online Access: | https://hal.archives-ouvertes.fr/hal-01507594 https://doi.org/10.1111/1365-2435.12729 |
Summary: | 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 ... |
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