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How Big Is It Really? Assessing the Efficacy of Indirect Estimates of Body Size in Asian Elephants

Information on an organism’s body size is pivotal in understanding its life history and fitness, as well as helping inform conservation measures. However, for many species, particularly large-bodied wild animals, taking accurate body size measurements can be a challenge. Various means to estimate bo...

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Autores principales: Chapman, Simon N., Mumby, Hannah S., Crawley, Jennie A. H., Mar, Khyne U., Htut, Win, Thura Soe, Aung, Aung, Htoo Htoo, Lummaa, Virpi
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4777392/
https://www.ncbi.nlm.nih.gov/pubmed/26938085
http://dx.doi.org/10.1371/journal.pone.0150533
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author Chapman, Simon N.
Mumby, Hannah S.
Crawley, Jennie A. H.
Mar, Khyne U.
Htut, Win
Thura Soe, Aung
Aung, Htoo Htoo
Lummaa, Virpi
author_facet Chapman, Simon N.
Mumby, Hannah S.
Crawley, Jennie A. H.
Mar, Khyne U.
Htut, Win
Thura Soe, Aung
Aung, Htoo Htoo
Lummaa, Virpi
author_sort Chapman, Simon N.
collection PubMed
description Information on an organism’s body size is pivotal in understanding its life history and fitness, as well as helping inform conservation measures. However, for many species, particularly large-bodied wild animals, taking accurate body size measurements can be a challenge. Various means to estimate body size have been employed, from more direct methods such as using photogrammetry to obtain height or length measurements, to indirect prediction of weight using other body morphometrics or even the size of dung boli. It is often unclear how accurate these measures are because they cannot be compared to objective measures. Here, we investigate how well existing estimation equations predict the actual body weight of Asian elephants Elephas maximus, using body measurements (height, chest girth, length, foot circumference and neck circumference) taken directly from a large population of semi-captive animals in Myanmar (n = 404). We then define new and better fitting formulas to predict body weight in Myanmar elephants from these readily available measures. We also investigate whether the important parameters height and chest girth can be estimated from photographs (n = 151). Our results show considerable variation in the ability of existing estimation equations to predict weight, and that the equations proposed in this paper predict weight better in almost all circumstances. We also find that measurements from standardised photographs reflect body height and chest girth after applying minor adjustments. Our results have implications for size estimation of large wild animals in the field, as well as for management in captive settings.
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spelling pubmed-47773922016-03-10 How Big Is It Really? Assessing the Efficacy of Indirect Estimates of Body Size in Asian Elephants Chapman, Simon N. Mumby, Hannah S. Crawley, Jennie A. H. Mar, Khyne U. Htut, Win Thura Soe, Aung Aung, Htoo Htoo Lummaa, Virpi PLoS One Research Article Information on an organism’s body size is pivotal in understanding its life history and fitness, as well as helping inform conservation measures. However, for many species, particularly large-bodied wild animals, taking accurate body size measurements can be a challenge. Various means to estimate body size have been employed, from more direct methods such as using photogrammetry to obtain height or length measurements, to indirect prediction of weight using other body morphometrics or even the size of dung boli. It is often unclear how accurate these measures are because they cannot be compared to objective measures. Here, we investigate how well existing estimation equations predict the actual body weight of Asian elephants Elephas maximus, using body measurements (height, chest girth, length, foot circumference and neck circumference) taken directly from a large population of semi-captive animals in Myanmar (n = 404). We then define new and better fitting formulas to predict body weight in Myanmar elephants from these readily available measures. We also investigate whether the important parameters height and chest girth can be estimated from photographs (n = 151). Our results show considerable variation in the ability of existing estimation equations to predict weight, and that the equations proposed in this paper predict weight better in almost all circumstances. We also find that measurements from standardised photographs reflect body height and chest girth after applying minor adjustments. Our results have implications for size estimation of large wild animals in the field, as well as for management in captive settings. Public Library of Science 2016-03-03 /pmc/articles/PMC4777392/ /pubmed/26938085 http://dx.doi.org/10.1371/journal.pone.0150533 Text en © 2016 Chapman 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, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Chapman, Simon N.
Mumby, Hannah S.
Crawley, Jennie A. H.
Mar, Khyne U.
Htut, Win
Thura Soe, Aung
Aung, Htoo Htoo
Lummaa, Virpi
How Big Is It Really? Assessing the Efficacy of Indirect Estimates of Body Size in Asian Elephants
title How Big Is It Really? Assessing the Efficacy of Indirect Estimates of Body Size in Asian Elephants
title_full How Big Is It Really? Assessing the Efficacy of Indirect Estimates of Body Size in Asian Elephants
title_fullStr How Big Is It Really? Assessing the Efficacy of Indirect Estimates of Body Size in Asian Elephants
title_full_unstemmed How Big Is It Really? Assessing the Efficacy of Indirect Estimates of Body Size in Asian Elephants
title_short How Big Is It Really? Assessing the Efficacy of Indirect Estimates of Body Size in Asian Elephants
title_sort how big is it really? assessing the efficacy of indirect estimates of body size in asian elephants
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4777392/
https://www.ncbi.nlm.nih.gov/pubmed/26938085
http://dx.doi.org/10.1371/journal.pone.0150533
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