Energetic modelling: A comparison of the different approaches used in seabirds
Résumé
Studying energetics of marine top predators is essential to understand their role within food-webs and
mechanisms associated with their survival and population dynamics. Several methods exist to estimate
energy expenditure in captive and free-ranging animals. However, most of them are difficult to implement,
restrained to specific periods, and are consequently inappropriate for seabirds. Supplementary and
complementary approaches are therefore needed, and the use of modelling appears as an excellent option
allowing energetic studies when field data collection is challenging. Currently three main energetics models
are used, with various degrees of complexity and accuracy: allometric equations, time–energy-budget
analyses and thermodynamic models. However, a comparison of their practicability and accuracy was still
lacking. Here, we present an overview of these 3 model types, their characteristics, advantages and
disadvantages, and areas of application in seabirds. We then investigate their accuracy by using them in
parallel for the same dataset, and by comparing outputs with direct measurements (doubly-labelled water
technique). We show that, when detailed data are available, time–energy–budget analysis is the best model
to accurately predict seabird energy expenditures. Conversely, thermodynamic modelling allows reasonably
accurate calculations when field data are scarce, and is therefore ideal to study energetics during the interbreeding
season.