Depletion of deep marine food patches forces divers to give up early
Summary Many optimal foraging models for diving animals examine strategies that maximize time spent in the foraging zone, assuming that prey acquisition increases linearly with search time. Other models have considered the effect of patch quality and predict a net energetic benefit if dives where no...
Published in: | Journal of Animal Ecology |
---|---|
Main Authors: | , , , , |
Other Authors: | |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Wiley
2012
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1111/j.1365-2656.2012.02021.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-2656.2012.02021.x https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2656.2012.02021.x |
id |
crwiley:10.1111/j.1365-2656.2012.02021.x |
---|---|
record_format |
openpolar |
spelling |
crwiley:10.1111/j.1365-2656.2012.02021.x 2024-06-02T08:06:01+00:00 Depletion of deep marine food patches forces divers to give up early Thums, Michele Bradshaw, Corey J. A. Sumner, Michael D. Horsburgh, Judy M. Hindell, Mark A. Hays, Graeme 2012 http://dx.doi.org/10.1111/j.1365-2656.2012.02021.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-2656.2012.02021.x https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2656.2012.02021.x en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Journal of Animal Ecology volume 82, issue 1, page 72-83 ISSN 0021-8790 1365-2656 journal-article 2012 crwiley https://doi.org/10.1111/j.1365-2656.2012.02021.x 2024-05-03T11:39:03Z Summary Many optimal foraging models for diving animals examine strategies that maximize time spent in the foraging zone, assuming that prey acquisition increases linearly with search time. Other models have considered the effect of patch quality and predict a net energetic benefit if dives where no prey is encountered early in the dive are abandoned. For deep divers, however, the energetic benefit of giving up is reduced owing to the elevated energy costs associated with descending to physiologically hostile depths, so patch residence time should be invariant. Others consider an asymptotic gain function where the decision to leave a patch is driven by patch‐depletion effects – the marginal value theorem. As predator behaviour is increasingly being used as an index of marine resource density and distribution, it is important to understand the nature of this gain function. We investigated the dive behaviour of the world's deepest‐diving seal, the southern elephant seal M irounga leonina , in response to patch quality. Testing these models has largely been limited to controlled experiments on captive animals. By integrating in situ measurements of the seal's relative lipid content obtained from drift rate data (a measure of foraging success) with area‐restricted search behaviour identified from first‐passage time analysis, we identified regions of high‐ and low‐quality patches. Dive durations and bottom times were not invariant and did not increase in regions of high quality; rather, both were longer when patches were of relatively low quality. This is consistent with the predictions of the marginal value theorem and provides support for a nonlinear relationship between search time and prey acquisition. We also found higher descent and ascent rates in high‐quality patches suggesting that seals minimized travel time to the foraging patch when quality was high; however, this was not achieved by increasing speed or dive angle. Relative body lipid content was an important predictor of dive behaviour. Seals did not ... Article in Journal/Newspaper Elephant Seal Southern Elephant Seal Wiley Online Library Journal of Animal Ecology 82 1 72 83 |
institution |
Open Polar |
collection |
Wiley Online Library |
op_collection_id |
crwiley |
language |
English |
description |
Summary Many optimal foraging models for diving animals examine strategies that maximize time spent in the foraging zone, assuming that prey acquisition increases linearly with search time. Other models have considered the effect of patch quality and predict a net energetic benefit if dives where no prey is encountered early in the dive are abandoned. For deep divers, however, the energetic benefit of giving up is reduced owing to the elevated energy costs associated with descending to physiologically hostile depths, so patch residence time should be invariant. Others consider an asymptotic gain function where the decision to leave a patch is driven by patch‐depletion effects – the marginal value theorem. As predator behaviour is increasingly being used as an index of marine resource density and distribution, it is important to understand the nature of this gain function. We investigated the dive behaviour of the world's deepest‐diving seal, the southern elephant seal M irounga leonina , in response to patch quality. Testing these models has largely been limited to controlled experiments on captive animals. By integrating in situ measurements of the seal's relative lipid content obtained from drift rate data (a measure of foraging success) with area‐restricted search behaviour identified from first‐passage time analysis, we identified regions of high‐ and low‐quality patches. Dive durations and bottom times were not invariant and did not increase in regions of high quality; rather, both were longer when patches were of relatively low quality. This is consistent with the predictions of the marginal value theorem and provides support for a nonlinear relationship between search time and prey acquisition. We also found higher descent and ascent rates in high‐quality patches suggesting that seals minimized travel time to the foraging patch when quality was high; however, this was not achieved by increasing speed or dive angle. Relative body lipid content was an important predictor of dive behaviour. Seals did not ... |
author2 |
Hays, Graeme |
format |
Article in Journal/Newspaper |
author |
Thums, Michele Bradshaw, Corey J. A. Sumner, Michael D. Horsburgh, Judy M. Hindell, Mark A. |
spellingShingle |
Thums, Michele Bradshaw, Corey J. A. Sumner, Michael D. Horsburgh, Judy M. Hindell, Mark A. Depletion of deep marine food patches forces divers to give up early |
author_facet |
Thums, Michele Bradshaw, Corey J. A. Sumner, Michael D. Horsburgh, Judy M. Hindell, Mark A. |
author_sort |
Thums, Michele |
title |
Depletion of deep marine food patches forces divers to give up early |
title_short |
Depletion of deep marine food patches forces divers to give up early |
title_full |
Depletion of deep marine food patches forces divers to give up early |
title_fullStr |
Depletion of deep marine food patches forces divers to give up early |
title_full_unstemmed |
Depletion of deep marine food patches forces divers to give up early |
title_sort |
depletion of deep marine food patches forces divers to give up early |
publisher |
Wiley |
publishDate |
2012 |
url |
http://dx.doi.org/10.1111/j.1365-2656.2012.02021.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-2656.2012.02021.x https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2656.2012.02021.x |
genre |
Elephant Seal Southern Elephant Seal |
genre_facet |
Elephant Seal Southern Elephant Seal |
op_source |
Journal of Animal Ecology volume 82, issue 1, page 72-83 ISSN 0021-8790 1365-2656 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/j.1365-2656.2012.02021.x |
container_title |
Journal of Animal Ecology |
container_volume |
82 |
container_issue |
1 |
container_start_page |
72 |
op_container_end_page |
83 |
_version_ |
1800750900515438592 |