Track and dive-based movement metrics do not predict the number of prey encountered by a marine predator
Abstract Background Studying animal movement in the context of the optimal foraging theory has led to the development of simple movement metrics for inferring feeding activity. Yet, the predictive capacity of these metrics in natural environments has been given little attention, raising serious ques...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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BMC
2023-01-01
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| Series: | Movement Ecology |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s40462-022-00361-2 |
| _version_ | 1797945647758835712 |
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| author | Hassen Allegue Denis Réale Baptiste Picard Christophe Guinet |
| author_facet | Hassen Allegue Denis Réale Baptiste Picard Christophe Guinet |
| author_sort | Hassen Allegue |
| collection | DOAJ |
| description | Abstract Background Studying animal movement in the context of the optimal foraging theory has led to the development of simple movement metrics for inferring feeding activity. Yet, the predictive capacity of these metrics in natural environments has been given little attention, raising serious questions of the validity of these metrics. The aim of this study is to test whether simple continuous movement metrics predict feeding intensity in a marine predator, the southern elephant seal (SES; Mirounga leonine), and investigate potential factors influencing the predictive capacity of these metrics. Methods We equipped 21 female SES from the Kerguelen Archipelago with loggers and recorded their movements during post-breeding foraging trips at sea. From accelerometry, we estimated the number of prey encounter events (nPEE) and used it as a reference for feeding intensity. We also extracted several track- and dive-based movement metrics and evaluated how well they explain and predict the variance in nPEE. We conducted our analysis at two temporal scales (dive and day), with two dive profile resolutions (high at 1 Hz and low with five dive segments), and two types of models (linear models and regression trees). Results We found that none of the movement metrics predict nPEE with satisfactory power. The vertical transit rates (primarily the ascent rate) during dives had the best predictive performance among all metrics. Dive metrics performed better than track metrics and all metrics performed on average better at the scale of days than the scale of dives. However, the performance of the models at the scale of days showed higher variability among individuals suggesting distinct foraging tactics. Dive-based metrics performed better when computed from high-resolution dive profiles than low-resolution dive profiles. Finally, regression trees produced more accurate predictions than linear models. Conclusions Our study reveals that simple movement metrics do not predict feeding activity in free-ranging marine predators. This could emerge from differences between individuals, temporal scales, and the data resolution used, among many other factors. We conclude that these simple metrics should be avoided or carefully tested a priori with the studied species and the ecological context to account for significant influencing factors. |
| first_indexed | 2024-04-10T20:58:26Z |
| format | Article |
| id | doaj.art-0551e1ea3a0d4f6baec907b93e06248a |
| institution | Directory Open Access Journal |
| issn | 2051-3933 |
| language | English |
| last_indexed | 2024-04-10T20:58:26Z |
| publishDate | 2023-01-01 |
| publisher | BMC |
| record_format | Article |
| series | Movement Ecology |
| spelling | doaj.art-0551e1ea3a0d4f6baec907b93e06248a2023-01-22T12:28:30ZengBMCMovement Ecology2051-39332023-01-0111111910.1186/s40462-022-00361-2Track and dive-based movement metrics do not predict the number of prey encountered by a marine predatorHassen Allegue0Denis Réale1Baptiste Picard2Christophe Guinet3Département des Sciences Biologiques, Université du Québec à MontréalDépartement des Sciences Biologiques, Université du Québec à MontréalCentre d’Etudes Biologiques de Chizé, UMR7372 CNRS-La Rochelle UniversitéCentre d’Etudes Biologiques de Chizé, UMR7372 CNRS-La Rochelle UniversitéAbstract Background Studying animal movement in the context of the optimal foraging theory has led to the development of simple movement metrics for inferring feeding activity. Yet, the predictive capacity of these metrics in natural environments has been given little attention, raising serious questions of the validity of these metrics. The aim of this study is to test whether simple continuous movement metrics predict feeding intensity in a marine predator, the southern elephant seal (SES; Mirounga leonine), and investigate potential factors influencing the predictive capacity of these metrics. Methods We equipped 21 female SES from the Kerguelen Archipelago with loggers and recorded their movements during post-breeding foraging trips at sea. From accelerometry, we estimated the number of prey encounter events (nPEE) and used it as a reference for feeding intensity. We also extracted several track- and dive-based movement metrics and evaluated how well they explain and predict the variance in nPEE. We conducted our analysis at two temporal scales (dive and day), with two dive profile resolutions (high at 1 Hz and low with five dive segments), and two types of models (linear models and regression trees). Results We found that none of the movement metrics predict nPEE with satisfactory power. The vertical transit rates (primarily the ascent rate) during dives had the best predictive performance among all metrics. Dive metrics performed better than track metrics and all metrics performed on average better at the scale of days than the scale of dives. However, the performance of the models at the scale of days showed higher variability among individuals suggesting distinct foraging tactics. Dive-based metrics performed better when computed from high-resolution dive profiles than low-resolution dive profiles. Finally, regression trees produced more accurate predictions than linear models. Conclusions Our study reveals that simple movement metrics do not predict feeding activity in free-ranging marine predators. This could emerge from differences between individuals, temporal scales, and the data resolution used, among many other factors. We conclude that these simple metrics should be avoided or carefully tested a priori with the studied species and the ecological context to account for significant influencing factors.https://doi.org/10.1186/s40462-022-00361-2AccelerometryArea-restricted searchDiving behaviorForaging behaviorMarine predatorPrey encounter events |
| spellingShingle | Hassen Allegue Denis Réale Baptiste Picard Christophe Guinet Track and dive-based movement metrics do not predict the number of prey encountered by a marine predator Movement Ecology Accelerometry Area-restricted search Diving behavior Foraging behavior Marine predator Prey encounter events |
| title | Track and dive-based movement metrics do not predict the number of prey encountered by a marine predator |
| title_full | Track and dive-based movement metrics do not predict the number of prey encountered by a marine predator |
| title_fullStr | Track and dive-based movement metrics do not predict the number of prey encountered by a marine predator |
| title_full_unstemmed | Track and dive-based movement metrics do not predict the number of prey encountered by a marine predator |
| title_short | Track and dive-based movement metrics do not predict the number of prey encountered by a marine predator |
| title_sort | track and dive based movement metrics do not predict the number of prey encountered by a marine predator |
| topic | Accelerometry Area-restricted search Diving behavior Foraging behavior Marine predator Prey encounter events |
| url | https://doi.org/10.1186/s40462-022-00361-2 |
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