[MARMAM] New Publication: Rissos dolphins plan foraging dives

Brandon Southall brandon.southall at sea-inc.net
Fri Mar 16 01:48:26 PDT 2018


On behalf of my co-authors, I am pleased to provide information 
regarding our recent publication on interesting aspects of fine scale 
foraging behavior that we argue demonstrate advance planning in 
echolocation search strategies. The reference, link, and abstract are 
provided below and .pdfs are available upon request.


Brandon Southall

*Arranz, P., Benoit-Bird, K. J., Southall, B. L., Calambokidis, J., 
Friedlaender, A. S., & Tyack, P. L. (2018). Risso's dolphins plan 
foraging dives. /Journal of Experimental Biology/, /221/(4), jeb165209.*



Humans remember the past and use that information to plan future 
actions. Lab experiments that test memory for the location of food show 
that animals have a similar capability to act in anticipation of future 
needs, but less work has been done on animals foraging in the wild. We 
hypothesized that planning abilities are critical and common in 
breathhold divers who adjust each dive to forage on prey varying in 
quality, location and predictability within constraints of limited 
oxygen availability. We equipped Risso*’*s dolphins with 
sound-and-motion recording tags to reveal where they focus their 
attention through their externally observable echolocation and how they 
fine tune search strategies in response to expected and observed prey 
distribution. The information from the dolphins was integrated with 
synoptic prey data obtained from echosounders on an underwater vehicle. 
At the start of the dives, whales adjusted their echolocation inspection 
ranges in ways that suggest planning to forage at a particular depth. 
Once entering a productive prey layer, dolphins reduced their search 
range comparable to the scale of patches within the layer, suggesting 
that they were using echolocation to select prey within the patch. On 
ascent, their search range increased, indicating that they decided to 
stop foraging within that layer and started searching for prey in 
shallower layers. Information about prey, learned throughout the dive, 
was used to plan foraging in the next dive. Our results demonstrate that 
planning for future dives is modulated by spatial memory derived from 
multi-modal prey sampling (echoic, visual and capture) during earlier 
dives. [KEY WORDS: Predator*–*prey dynamics, Perceptual range, Grampus 
griseus, Animal decision making, Episodic-like memory, Foraging behaviour]

Brandon L. Southall, Ph.D.
President, Senior Scientist, SEA, Inc.
Research Associate, University of California, Santa Cruz
9099 Soquel Drive, Suite 8, Aptos, CA 95003, USA
831.332.8744 (mobile); 831.661.5177 (office); 831.661.5178 (fax)
Brandon.Southall at sea-inc.net; www.sea-inc.net

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