Passive acoustics suggest two different feeding mechanisms in the Atlantic walrus (Odobenus rosmarus rosmarus)

The vocal repertoire of walruses has been widely described in the bioacoustic literature. These marine mammals produce several distinct types of vocalizations for intraspecific communication during the breeding season. In this study, we provide the first evidence of walrus-generated sounds during fo...

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Bibliographic Details
Published in:Polar Biology
Main Authors: Jézéquel, Youenn, Mathias, Delphine, Olivier, Frédéric, Amice, Erwan, Chauvaud, Sylvain, Jolivet, Aurélie, Bonnel, Julien, Sejr, Mikael K., Chauvaud, Laurent
Format: Article in Journal/Newspaper
Language:English
Published: Springer Science and Business Media LLC 2022
Subjects:
Bioacoustics
Bivalves
Feeding behavior
Marine mammal
Young Sound fjord
Odobenus rosmarus
Polar Biology
walrus*
Online Access:https://archimer.ifremer.fr/doc/00777/88935/97549.pdf
https://doi.org/10.1007/s00300-022-03055-y
https://archimer.ifremer.fr/doc/00777/88935/
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Summary:The vocal repertoire of walruses has been widely described in the bioacoustic literature. These marine mammals produce several distinct types of vocalizations for intraspecific communication during the breeding season. In this study, we provide the first evidence of walrus-generated sounds during foraging dives when they feed on bivalves. We recorded two types of sounds that we associated to different feeding mechanisms. The first sound type was brief and low in frequency that we relate to the suction of soft parts from the bivalves’ shells through the use of walrus powerful tongues, which is the common feeding behavior reported in the walrus literature. We also recorded a second sound type composed of multiple broadband pulse trains. We hypothesize the latter were associated with bivalve shell cracking by walruses, which would represent a new feeding mechanism in the walrus literature. This new feeding mechanism is either related to bivalves’ ecology or to walruses removing the sediment when searching for food. During this study, we observed bivalves lying on the seafloor instead of being buried in the sediment in walrus feeding areas while scuba diving. As a result, walruses cannot use suction to feed on soft body part of bivalves and have to use another strategy, mastication. Our findings provide a first step towards using passive acoustics to quantify walrus behavior and feeding ecology.

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