Dynamic foraging of a top predator in a seasonal polar marine environment
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The seasonal movement of animals at broad spatial scales provides insight into life-history, ecology and conservation. By combining high-resolution satellite-tagged data with hierarchical Bayesian movement models, we can associate spatial patterns of movement with marine animal behavior. We used a multi-state mixture model to describe humpback whale traveling and area-restricted search states as they forage along the West Antarctic Peninsula. We estimated the change in the geography, composition and characteristics of these behavioral states through time. We show that whales later in the austral fall spent more time in movements associated with foraging, traveled at lower speeds between foraging areas, and shifted their distribution northward and inshore. Seasonal changes in movement are likely due to a combination of sea ice advance and regional shifts in the primary prey source. Our study is a step towards dynamic movement models in the marine environment at broad scales.
KeywordsAntarctica Antarctic krill Bayesian movement model Humpback whales Sea ice
Research was supported by Antarctic Wildlife Research Fund (ANT-0823101), NSF OPP National Science Foundation ANT-0823101, 1250208, and 1440435, International Whaling Commission, and the Southern Ocean Research Partnership awards under permits: NMFS 14907, 14809, and 14856, ACA Permits 2009-013 and 2015-011, Duke University IACUC A049-122-02 and OSU ACUP 4513. We are grateful to the Australian Antarctic Division for their support of this research, with special thanks to Nick Gales, Mike Double, Elanor Bell, and Virginia Andrews-Goff. Thanks to Rodolfo Werner for his stimulating feedback. Source code and data visualizations are available on github (https://bw4sz.github.io/WhaleShape/).
Author contribution statement
AF designed the sampling and collected the data. BW analyzed the data. BW and AF wrote the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare no conflicts of interest.
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