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International audience; In the marine environment, track and dive parameter data (obtained using Argos or GPS tags and time–depth recorders) are commonly used to provide proxies for foraging behaviour of marine predators. However, their accuracy is rarely assessed. Recently, the addition of head-mounted accelerometers has allowed for detection of prey capture attempts (PCAs) at sea, allowing for more accurate estimations of foraging behaviour. Despite increased numbers of such devices being deployed, their use is still marginal compared with other tools which measure track and dive parameters. The objectives of our study were (1) to identify the most relevant combination of tracking and diving metrics in predicting the frequency of PCAs in female southern elephant seals Mirounga leonina from the Kerguelen Islands, and (2) to apply it to a broader range of individuals for which only tracking and diving data were available. The results of our models were consistent with the optimal foraging theory as well as the optimal diving theory. The model with the best predictive performance was the one that combined both tracking and diving information. However, most of the variability in the number of PCAs could be solely explained by changes in the diving behaviour of seals. Finally, we used the best predictive model on 20 individuals, which had not been fitted with accelerometers, to determine their main foraging zones. The behavioural indicators established in this study constitute a useful ecological tool for population monitoring and conservation purposes.

article in press; A new algorithm for the tracking of charged particles through timing detectors is proposed, providing as output the coordinates, slopes, velocity and an offset time at a given reference plane. The algorithm is based on a least squares method and works directly with first level data provided by the detectors, either coordinates or readout times. Some general analytical solutions valid for different detector layouts are given. Advantages compared to traditional straight track fitting algorithms are discussed.