Direct At-Sea Observations of Elephant Seals (Mirounga spp.) to Help Interpret Digital Bio-logging Data

• Published in: The Open Biology Journal
• Main Authors: van den Hoff, John, Thalmann, Sam
• Format: Article in Journal/Newspaper
• Language: English
• Published: Bentham Science Publishers Ltd. 2020
• Subjects: General Agricultural and Biological Sciences; General Biochemistry, Genetics and Molecular Biology; Elephant Seal; Elephant Seals
• Online Access: http://dx.doi.org/10.2174/1874196702008010001; https://openbiologyjournal.com/contents/volumes/V8/TOBIOJ-8-1/TOBIOJ-8-1.pdf; https://openbiologyjournal.com/contents/volumes/V8/TOBIOJ-8-1/TOBIOJ-8-1.xml

Background: A key short-fall with animal-borne bio-logging instruments, which collect digital time-series data regarding the foraging behaviours of cryptic marine mammal species, is validating those data against in situ behaviours. Objective: To collate direct observations of elephant seal feeding behaviour to help interpret foraging behaviours inferred from Time-Depth Recorder (TDR) data. Methods: Direct observations of elephant seal foraging behaviour were collated from the published literature using a search of the world-wide-web. Those observations were supplemented with an unpublished record. Results: Two deep-sea video recordings and six surface sightings of elephant seals ingesting prey were collated. Each observation either supported or suggested an alternative to behaviours derived from digital time-depth profiles. The tendency for elephant seals to surface following the capture of large prey suggests precipitous drops in stomach temperature at the sea-surface, which have been recorded and interpreted as drinking events, more likely represent the ingestion of large prey items. Conclusion: Direct observations of marine mammal foraging behaviours are rare, yet they provide a means to continuously evaluate and interpret outcomes of bio-logging instruments.