Dear all,
My co-authors and I are happy to announce our paper on a spin dive
performed by Risso's dolphins that they specifically enables them to
very quickly reach deep prey layers. Their foraging dive starts with a
rapid spin, a the surface, and reaches 300-600 m deep. Off the Azores,
Risso's dolphin foraging depth also directly traced the depth of the
deep scattering layer, foraging deep during the day and shallow at
night.
Link to the paper:
https://royalsocietypublishing.org/doi/10.1098/rsos.202320
ABSTRACT
Foraging decisions of deep-diving cetaceans can provide fundamental
insight into food web dynamics of the deep pelagic ocean. Cetacean
optimal foraging entails a tight balance between oxygen-conserving dive
strategies and access to deep-dwelling prey of sufficient energetic
reward. Risso's dolphins (Grampus griseus) displayed a thus far unknown
dive strategy, which we termed the spin dive. Dives started with intense
stroking and right-sided lateral rotation. This remarkable behaviour
resulted in a rapid descent. By tracking the fine-scale foraging
behaviour of seven tagged individuals, matched with prey layer
recordings, we tested the hypothesis that spin dives are foraging dives
targeting deep-dwelling prey. Hunting depth traced the diel movement of
the deep scattering layer, a dense aggregation of prey, that resides
deep during the day and near-surface at night. Individuals shifted their
foraging strategy from deep spin dives to shallow non-spin dives around
dusk. Spin dives were significantly faster, steeper and deeper than
non-spin dives, effectively minimizing transit time to bountiful
mesopelagic prey, and were focused on periods when the migratory prey
might be easier to catch. Hence, whereas Risso's dolphins were mostly
shallow, nocturnal foragers, their spin dives enabled extended and
rewarding diurnal foraging on deep-dwelling prey.
Reference
Fleur Visser, Onno A. Keller, Machiel G. Oudejans, Douglas P. Nowacek,
Annebelle C.M. Kok, Jef Huisman and Elisabeth H.M. Sterck Risso’s
dolphins perform spin dives to target deep-dwelling prey
Royal Society Open Science 1 dec 2021
https://doi.org/10.1098/rsos.202320
All the best,
Fleur
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