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Development of a noninvasive photograph-based method for the evaluation of body condition in free-ranging brown bears

Body condition is an important determinant of health, and its evaluation has practical applications for the conservation and management of mammals. We developed a noninvasive method that uses photographs to assess the body condition of free-ranging brown bears (Ursus arctos) in the Shiretoko Peninsu...

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Autores principales: Shirane, Yuri, Mori, Fumihiko, Yamanaka, Masami, Nakanishi, Masanao, Ishinazaka, Tsuyoshi, Mano, Tsutomu, Jimbo, Mina, Sashika, Mariko, Tsubota, Toshio, Shimozuru, Michito
Formato: Online Artículo Texto
Lenguaje:English
Publicado: PeerJ Inc. 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7505064/
https://www.ncbi.nlm.nih.gov/pubmed/32999770
http://dx.doi.org/10.7717/peerj.9982
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author Shirane, Yuri
Mori, Fumihiko
Yamanaka, Masami
Nakanishi, Masanao
Ishinazaka, Tsuyoshi
Mano, Tsutomu
Jimbo, Mina
Sashika, Mariko
Tsubota, Toshio
Shimozuru, Michito
author_facet Shirane, Yuri
Mori, Fumihiko
Yamanaka, Masami
Nakanishi, Masanao
Ishinazaka, Tsuyoshi
Mano, Tsutomu
Jimbo, Mina
Sashika, Mariko
Tsubota, Toshio
Shimozuru, Michito
author_sort Shirane, Yuri
collection PubMed
description Body condition is an important determinant of health, and its evaluation has practical applications for the conservation and management of mammals. We developed a noninvasive method that uses photographs to assess the body condition of free-ranging brown bears (Ursus arctos) in the Shiretoko Peninsula, Hokkaido, Japan. First, we weighed and measured 476 bears captured during 1998–2017 and calculated their body condition index (BCI) based on residuals from the regression of body mass against body length. BCI showed seasonal changes and was lower in spring and summer than in autumn. The torso height:body length ratio was strongly correlated with BCI, which suggests that it can be used as an indicator of body condition. Second, we examined the precision of photograph-based measurements using an identifiable bear in the Rusha area, a special wildlife protection area on the peninsula. A total of 220 lateral photographs of this bear were taken September 24–26, 2017, and classified according to bear posture. The torso height:body/torso length ratio was calculated with four measurement methods and compared among bear postures in the photographs. The results showed torso height:horizontal torso length (TH:HTL) to be the indicator that could be applied to photographs of the most diverse postures, and its coefficient of variation for measurements was <5%. In addition, when analyzing photographs of this bear taken from June to October during 2016–2018, TH:HTL was significantly higher in autumn than in spring/summer, which indicates that this ratio reflects seasonal changes in body condition in wild bears. Third, we calculated BCI from actual measurements of seven females captured in the Rusha area and TH:HTL from photographs of the same individuals. We found a significant positive relationship between TH:HTL and BCI, which suggests that the body condition of brown bears can be estimated with high accuracy based on photographs. Our simple and accurate method is useful for monitoring bear body condition repeatedly over the years and contributes to further investigation of the relationships among body condition, food habits, and reproductive success.
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spelling pubmed-75050642020-09-29 Development of a noninvasive photograph-based method for the evaluation of body condition in free-ranging brown bears Shirane, Yuri Mori, Fumihiko Yamanaka, Masami Nakanishi, Masanao Ishinazaka, Tsuyoshi Mano, Tsutomu Jimbo, Mina Sashika, Mariko Tsubota, Toshio Shimozuru, Michito PeerJ Animal Behavior Body condition is an important determinant of health, and its evaluation has practical applications for the conservation and management of mammals. We developed a noninvasive method that uses photographs to assess the body condition of free-ranging brown bears (Ursus arctos) in the Shiretoko Peninsula, Hokkaido, Japan. First, we weighed and measured 476 bears captured during 1998–2017 and calculated their body condition index (BCI) based on residuals from the regression of body mass against body length. BCI showed seasonal changes and was lower in spring and summer than in autumn. The torso height:body length ratio was strongly correlated with BCI, which suggests that it can be used as an indicator of body condition. Second, we examined the precision of photograph-based measurements using an identifiable bear in the Rusha area, a special wildlife protection area on the peninsula. A total of 220 lateral photographs of this bear were taken September 24–26, 2017, and classified according to bear posture. The torso height:body/torso length ratio was calculated with four measurement methods and compared among bear postures in the photographs. The results showed torso height:horizontal torso length (TH:HTL) to be the indicator that could be applied to photographs of the most diverse postures, and its coefficient of variation for measurements was <5%. In addition, when analyzing photographs of this bear taken from June to October during 2016–2018, TH:HTL was significantly higher in autumn than in spring/summer, which indicates that this ratio reflects seasonal changes in body condition in wild bears. Third, we calculated BCI from actual measurements of seven females captured in the Rusha area and TH:HTL from photographs of the same individuals. We found a significant positive relationship between TH:HTL and BCI, which suggests that the body condition of brown bears can be estimated with high accuracy based on photographs. Our simple and accurate method is useful for monitoring bear body condition repeatedly over the years and contributes to further investigation of the relationships among body condition, food habits, and reproductive success. PeerJ Inc. 2020-09-18 /pmc/articles/PMC7505064/ /pubmed/32999770 http://dx.doi.org/10.7717/peerj.9982 Text en ©2020 Shirane et al. https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (https://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
Shirane, Yuri
Mori, Fumihiko
Yamanaka, Masami
Nakanishi, Masanao
Ishinazaka, Tsuyoshi
Mano, Tsutomu
Jimbo, Mina
Sashika, Mariko
Tsubota, Toshio
Shimozuru, Michito
Development of a noninvasive photograph-based method for the evaluation of body condition in free-ranging brown bears
title Development of a noninvasive photograph-based method for the evaluation of body condition in free-ranging brown bears
title_full Development of a noninvasive photograph-based method for the evaluation of body condition in free-ranging brown bears
title_fullStr Development of a noninvasive photograph-based method for the evaluation of body condition in free-ranging brown bears
title_full_unstemmed Development of a noninvasive photograph-based method for the evaluation of body condition in free-ranging brown bears
title_short Development of a noninvasive photograph-based method for the evaluation of body condition in free-ranging brown bears
title_sort development of a noninvasive photograph-based method for the evaluation of body condition in free-ranging brown bears
topic Animal Behavior
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7505064/
https://www.ncbi.nlm.nih.gov/pubmed/32999770
http://dx.doi.org/10.7717/peerj.9982
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