Abstract
ABSTRACTUnderstanding energy use is central to understanding an animal's physiological and behavioural ecology. However, directly measuring energy expenditure in free-ranging animals is inherently difficult. The doubly labelled water (DLW) method is widely used to investigate energy expenditure in a range of taxa. Although reliable, DLW data collection and analysis is both financially costly and time consuming. Dynamic body acceleration (e.g. VeDBA) calculated from animal-borne accelerometers has been used to determine behavioural patterns, and is increasingly being used as a proxy for energy expenditure. Still its performance as a proxy for energy expenditure in free-ranging animals is not well established and requires validation against established methods. In the present study, the relationship between VeDBA and the at-sea metabolic rate calculated from DLW was investigated in little penguins (Eudyptula minor) using three approaches. Both in a simple correlation and activity-specific approaches were shown to be good predictors of at-sea metabolic rate. The third approach using activity-specific energy expenditure values obtained from literature did not accurately calculate the energy expended by individuals. However, all three approaches were significantly strengthened by the addition of mean horizontal travel speed. These results provide validation for the use of accelerometry as a proxy for energy expenditure and show how energy expenditure may be influenced by both individual behaviour and environmental conditions.
Highlights
Energy is a finite resource and a central currency in determining the behaviour and physiology of animals (Butler et al, 2004; Speakman and Król, 2010)
Four individuals from GI returned from their foraging trip with blood isotopic levels too close to background levels for accurate measures of at-sea energy expenditure to be determined. 12 individuals remained on land following injection of doubly labelled water method (DLW) and these individuals were used to determine daily energy expenditure on land (DEEDLW-L, Table 1)
Mass specific at-sea metabolic rate (DEEDLW-S kJ kg−1 d−1) was obtained over a single foraging trip for eight individuals and over two foraging trips for one individual with blood samples collected between foraging trips (N=10; Table 2)
Summary
Energy is a finite resource and a central currency in determining the behaviour and physiology of animals (Butler et al, 2004; Speakman and Król, 2010). How animals allocate their time and energy critically influences important aspects of their life history, including food acquisition, growth and reproduction (McNamara and Houston, 1996). Each technique is associated with a suite of drawbacks, namely accuracy (Goldstein, 1988), ability to calibrate measurements on captive populations (Goldstein, 1988; Morrier and McNeil, 1991), invasiveness (Green, 2011) and cost of analyses (Butler et al, 2004; Speakman, 1997)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
