Growing into it : evidence of an ontogenetic shift in grey whale use of foraging tactics
Abstract
Individual specialization may occur relative to diet, behaviour or spatial distribution, potentially leading to differential resource and space use within a population. While specializations have been documented across many animal populations, the underlaying causes of individual specialization (e.g. morphology, age or sex) are not always identified. Causes of specialization can be especially challenging to uncover for large, long-lived marine animals. We used a Bayesian multilevel, multinomial logistic regression model to study the relationships between grey whale, Eschrichtius robustus, use of foraging tactics and morphology (body length and condition), while accounting for habitat characteristics and individual variation in tactic use. The model was informed by a 7-year longitudinal data set of concurrent morphology and foraging behaviour collected using drones. We found evidence of an ontogenetic shift in the use of foraging tactics associated with body length (a proxy for age). Individual specialization in behaviour was also associated with water depth and habitat. After accounting for the effects of these covariates, there was some residual individual level variation in the use of different foraging tactics. Our findings demonstrate variation in resource and habitat use within a baleen whale population at the individual level relative to body length and habitat, suggesting that individual spatial distribution and access to prey may vary by age class. Our results can be applied to investigate whether juveniles and adults differ in their foraging success and resilience to stressors.
Citation
Bird , C , Pirotta , E , New , L , Bierlich , KC , Donnelly , M , Hildebrand , L , Fernandez Ajó , A & Torres , L 2024 , ' Growing into it : evidence of an ontogenetic shift in grey whale use of foraging tactics ' , Animal Behaviour , vol. 214 , pp. 121-135 . https://doi.org/10.1016/j.anbehav.2024.06.004
Publication
Animal Behaviour
Status
Peer reviewed
ISSN
0003-3472Type
Journal article
Description
Funding: Alexa Kownacki Endowed Research Award Fund. Data collection was supported by the NOAA National Marine Fisheries Service Office of Science and Technology Ocean Acoustics Program (2016 and 2017; 50-27), the Oregon Sea Grant Program Development funds (2018; RECO-40-PD), the Oregon State University Marine Mammal Institute (2019) and the Office of Naval Research Marine Mammals and Biology program (2020e2022; N00014-20-1-2760).Collections
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