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Using accelerometers to develop time-energy budgets of wild fur seals from captive surrogates
BACKGROUND: Accurate time-energy budgets summarise an animal’s energy expenditure in a given environment, and are potentially a sensitive indicator of how an animal responds to changing resources. Deriving accurate time-energy budgets requires an estimate of time spent in different activities and of...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
PeerJ Inc.
2018
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6204822/ https://www.ncbi.nlm.nih.gov/pubmed/30386705 http://dx.doi.org/10.7717/peerj.5814 |
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author | Ladds, Monique A. Salton, Marcus Hocking, David P. McIntosh, Rebecca R. Thompson, Adam P. Slip, David J. Harcourt, Robert G. |
author_facet | Ladds, Monique A. Salton, Marcus Hocking, David P. McIntosh, Rebecca R. Thompson, Adam P. Slip, David J. Harcourt, Robert G. |
author_sort | Ladds, Monique A. |
collection | PubMed |
description | BACKGROUND: Accurate time-energy budgets summarise an animal’s energy expenditure in a given environment, and are potentially a sensitive indicator of how an animal responds to changing resources. Deriving accurate time-energy budgets requires an estimate of time spent in different activities and of the energetic cost of that activity. Bio-loggers (e.g., accelerometers) may provide a solution for monitoring animals such as fur seals that make long-duration foraging trips. Using low resolution to record behaviour may aid in the transmission of data, negating the need to recover the device. METHODS: This study used controlled captive experiments and previous energetic research to derive time-energy budgets of juvenile Australian fur seals (Arctocephalus pusillus) equipped with tri-axial accelerometers. First, captive fur seals and sea lions were equipped with accelerometers recording at high (20 Hz) and low (1 Hz) resolutions, and their behaviour recorded. Using this data, machine learning models were trained to recognise four states—foraging, grooming, travelling and resting. Next, the energetic cost of each behaviour, as a function of location (land or water), season and digestive state (pre- or post-prandial) was estimated. Then, diving and movement data were collected from nine wild juvenile fur seals wearing accelerometers recording at high- and low- resolutions. Models developed from captive seals were applied to accelerometry data from wild juvenile Australian fur seals and, finally, their time-energy budgets were reconstructed. RESULTS: Behaviour classification models built with low resolution (1 Hz) data correctly classified captive seal behaviours with very high accuracy (up to 90%) and recorded without interruption. Therefore, time-energy budgets of wild fur seals were constructed with these data. The reconstructed time-energy budgets revealed that juvenile fur seals expended the same amount of energy as adults of similar species. No significant differences in daily energy expenditure (DEE) were found across sex or season (winter or summer), but fur seals rested more when their energy expenditure was expected to be higher. Juvenile fur seals used behavioural compensatory techniques to conserve energy during activities that were expected to have high energetic outputs (such as diving). DISCUSSION: As low resolution accelerometry (1 Hz) was able to classify behaviour with very high accuracy, future studies may be able to transmit more data at a lower rate, reducing the need for tag recovery. Reconstructed time-energy budgets demonstrated that juvenile fur seals appear to expend the same amount of energy as their adult counterparts. Through pairing estimates of energy expenditure with behaviour this study demonstrates the potential to understand how fur seals expend energy, and where and how behavioural compensations are made to retain constant energy expenditure over a short (dive) and long (season) period. |
format | Online Article Text |
id | pubmed-6204822 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | PeerJ Inc. |
record_format | MEDLINE/PubMed |
spelling | pubmed-62048222018-10-31 Using accelerometers to develop time-energy budgets of wild fur seals from captive surrogates Ladds, Monique A. Salton, Marcus Hocking, David P. McIntosh, Rebecca R. Thompson, Adam P. Slip, David J. Harcourt, Robert G. PeerJ Animal Behavior BACKGROUND: Accurate time-energy budgets summarise an animal’s energy expenditure in a given environment, and are potentially a sensitive indicator of how an animal responds to changing resources. Deriving accurate time-energy budgets requires an estimate of time spent in different activities and of the energetic cost of that activity. Bio-loggers (e.g., accelerometers) may provide a solution for monitoring animals such as fur seals that make long-duration foraging trips. Using low resolution to record behaviour may aid in the transmission of data, negating the need to recover the device. METHODS: This study used controlled captive experiments and previous energetic research to derive time-energy budgets of juvenile Australian fur seals (Arctocephalus pusillus) equipped with tri-axial accelerometers. First, captive fur seals and sea lions were equipped with accelerometers recording at high (20 Hz) and low (1 Hz) resolutions, and their behaviour recorded. Using this data, machine learning models were trained to recognise four states—foraging, grooming, travelling and resting. Next, the energetic cost of each behaviour, as a function of location (land or water), season and digestive state (pre- or post-prandial) was estimated. Then, diving and movement data were collected from nine wild juvenile fur seals wearing accelerometers recording at high- and low- resolutions. Models developed from captive seals were applied to accelerometry data from wild juvenile Australian fur seals and, finally, their time-energy budgets were reconstructed. RESULTS: Behaviour classification models built with low resolution (1 Hz) data correctly classified captive seal behaviours with very high accuracy (up to 90%) and recorded without interruption. Therefore, time-energy budgets of wild fur seals were constructed with these data. The reconstructed time-energy budgets revealed that juvenile fur seals expended the same amount of energy as adults of similar species. No significant differences in daily energy expenditure (DEE) were found across sex or season (winter or summer), but fur seals rested more when their energy expenditure was expected to be higher. Juvenile fur seals used behavioural compensatory techniques to conserve energy during activities that were expected to have high energetic outputs (such as diving). DISCUSSION: As low resolution accelerometry (1 Hz) was able to classify behaviour with very high accuracy, future studies may be able to transmit more data at a lower rate, reducing the need for tag recovery. Reconstructed time-energy budgets demonstrated that juvenile fur seals appear to expend the same amount of energy as their adult counterparts. Through pairing estimates of energy expenditure with behaviour this study demonstrates the potential to understand how fur seals expend energy, and where and how behavioural compensations are made to retain constant energy expenditure over a short (dive) and long (season) period. PeerJ Inc. 2018-10-26 /pmc/articles/PMC6204822/ /pubmed/30386705 http://dx.doi.org/10.7717/peerj.5814 Text en ©2018 Ladds et al. http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited. |
spellingShingle | Animal Behavior Ladds, Monique A. Salton, Marcus Hocking, David P. McIntosh, Rebecca R. Thompson, Adam P. Slip, David J. Harcourt, Robert G. Using accelerometers to develop time-energy budgets of wild fur seals from captive surrogates |
title | Using accelerometers to develop time-energy budgets of wild fur seals from captive surrogates |
title_full | Using accelerometers to develop time-energy budgets of wild fur seals from captive surrogates |
title_fullStr | Using accelerometers to develop time-energy budgets of wild fur seals from captive surrogates |
title_full_unstemmed | Using accelerometers to develop time-energy budgets of wild fur seals from captive surrogates |
title_short | Using accelerometers to develop time-energy budgets of wild fur seals from captive surrogates |
title_sort | using accelerometers to develop time-energy budgets of wild fur seals from captive surrogates |
topic | Animal Behavior |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6204822/ https://www.ncbi.nlm.nih.gov/pubmed/30386705 http://dx.doi.org/10.7717/peerj.5814 |
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