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Prey density and distribution drive the three-dimensional foraging strategies of the largest filter feeder

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Title Prey density and distribution drive the three-dimensional foraging strategies of the largest filter feeder
Names Goldbogen, Jeremy A. (creator)
Hazen, Elliott L. (creator)
Friedlaender, Ari S. (creator)
et al. (creator)
Date Issued 2015-07 (iso8601)
Note To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and British Ecological Society and published by John Wiley & Sons Ltd. It can be found at: http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291365-2435/
Abstract 1. Despite their importance in determining the rate of both energy gain and expenditure, how
the fine-scale kinematics of foraging are modified in response to changes in prey abundance
and distribution remain poorly understood in many animal ecosystems.
2. In the marine environment, bulk-filter feeders rely on dense aggregations of prey for energetically
efficient foraging. Rorqual whales (Balaenopteridae) exhibit a unique form of filter
feeding called lunge feeding, a process whereby discrete volumes of prey-laden water are intermittently
engulfed and filtered. In many large rorqual species the size of engulfed water mass is
commensurate with the whale’s body size, yet is engulfed in just a few seconds. This filter-feeding
mode thus requires precise coordination of the body and enlarged engulfment apparatus to
maximize capture efficiency.
3. Previous studies from whale-borne tags revealed that many rorqual species perform rolling behaviours
when foraging. It has been hypothesized that such acrobatic manoeuvres may be required
for efficient prey capture when prey manifest in small discrete patches, but to date there has been
no comprehensive analysis of prey patch characteristics during lunge feeding events. We developed
a null hypothesis that blue whale kinematics are independent of prey patch characteristics.
4. To test this hypothesis, we investigated the foraging performance of blue whales, the largest filter-feeding predator and their functional response to variability in their sole prey source, krill
using a generalized additive mixed model framework. We used a combination of animal-borne
movement sensors and hydroacoustic prey mapping to simultaneously quantify the threedimensional
foraging kinematics of blue whales (Balaenoptera musculus) and the characteristics
of targeted krill patches.
5. Our analyses rejected our null hypothesis, showing that blue whales performed more acrobatic
manoeuvres, including 180° and 360° rolling lunges, when foraging on low-density krill
patches. In contrast, whales targeting high-density krill patches involved less manoeuvring
during lunges and higher lunge feeding rates.
6. These data demonstrate that blue whales exhibit a range of adaptive foraging strategies that
maximize prey capture in different ecological contexts. Because first principles indicate that
manoeuvres require more energy compared with straight trajectories, our data reveal a previously
unrecognized level of complexity in predator–prey interactions that are not accounted
for in optimal foraging and energetic efficiency models.
Genre Article
Topic baleen whales
Identifier Goldbogen, J. A., Hazen, E. L., Friedlaender, A. S., Calambokidis, J., DeRuiter, S. L., Stimpert, A. K., & Southall, B. L. (2015). Prey density and distribution drive the three‐dimensional foraging strategies of the largest filter feeder. Functional Ecology, 29(7), 951-961, Special Issue. doi:10.1111/1365-2435.12395

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