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An Advanced Method to Assess the Diet of Free-Ranging Large Carnivores Based on Scats

BACKGROUND: The diet of free-ranging carnivores is an important part of their ecology. It is often determined from prey remains in scats. In many cases, scat analyses are the most efficient method but they require correction for potential biases. When the diet is expressed as proportions of consumed...

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Autores principales: Wachter, Bettina, Blanc, Anne-Sophie, Melzheimer, Jörg, Höner, Oliver P., Jago, Mark, Hofer, Heribert
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2012
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3371055/
https://www.ncbi.nlm.nih.gov/pubmed/22715373
http://dx.doi.org/10.1371/journal.pone.0038066
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author Wachter, Bettina
Blanc, Anne-Sophie
Melzheimer, Jörg
Höner, Oliver P.
Jago, Mark
Hofer, Heribert
author_facet Wachter, Bettina
Blanc, Anne-Sophie
Melzheimer, Jörg
Höner, Oliver P.
Jago, Mark
Hofer, Heribert
author_sort Wachter, Bettina
collection PubMed
description BACKGROUND: The diet of free-ranging carnivores is an important part of their ecology. It is often determined from prey remains in scats. In many cases, scat analyses are the most efficient method but they require correction for potential biases. When the diet is expressed as proportions of consumed mass of each prey species, the consumed prey mass to excrete one scat needs to be determined and corrected for prey body mass because the proportion of digestible to indigestible matter increases with prey body mass. Prey body mass can be corrected for by conducting feeding experiments using prey of various body masses and fitting a regression between consumed prey mass to excrete one scat and prey body mass (correction factor 1). When the diet is expressed as proportions of consumed individuals of each prey species and includes prey animals not completely consumed, the actual mass of each prey consumed by the carnivore needs to be controlled for (correction factor 2). No previous study controlled for this second bias. METHODOLOGY/PRINCIPAL FINDINGS: Here we use an extended series of feeding experiments on a large carnivore, the cheetah (Acinonyx jubatus), to establish both correction factors. In contrast to previous studies which fitted a linear regression for correction factor 1, we fitted a biologically more meaningful exponential regression model where the consumed prey mass to excrete one scat reaches an asymptote at large prey sizes. Using our protocol, we also derive correction factor 1 and 2 for other carnivore species and apply them to published studies. We show that the new method increases the number and proportion of consumed individuals in the diet for large prey animals compared to the conventional method. CONCLUSION/SIGNIFICANCE: Our results have important implications for the interpretation of scat-based studies in feeding ecology and the resolution of human-wildlife conflicts for the conservation of large carnivores.
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spelling pubmed-33710552012-06-19 An Advanced Method to Assess the Diet of Free-Ranging Large Carnivores Based on Scats Wachter, Bettina Blanc, Anne-Sophie Melzheimer, Jörg Höner, Oliver P. Jago, Mark Hofer, Heribert PLoS One Research Article BACKGROUND: The diet of free-ranging carnivores is an important part of their ecology. It is often determined from prey remains in scats. In many cases, scat analyses are the most efficient method but they require correction for potential biases. When the diet is expressed as proportions of consumed mass of each prey species, the consumed prey mass to excrete one scat needs to be determined and corrected for prey body mass because the proportion of digestible to indigestible matter increases with prey body mass. Prey body mass can be corrected for by conducting feeding experiments using prey of various body masses and fitting a regression between consumed prey mass to excrete one scat and prey body mass (correction factor 1). When the diet is expressed as proportions of consumed individuals of each prey species and includes prey animals not completely consumed, the actual mass of each prey consumed by the carnivore needs to be controlled for (correction factor 2). No previous study controlled for this second bias. METHODOLOGY/PRINCIPAL FINDINGS: Here we use an extended series of feeding experiments on a large carnivore, the cheetah (Acinonyx jubatus), to establish both correction factors. In contrast to previous studies which fitted a linear regression for correction factor 1, we fitted a biologically more meaningful exponential regression model where the consumed prey mass to excrete one scat reaches an asymptote at large prey sizes. Using our protocol, we also derive correction factor 1 and 2 for other carnivore species and apply them to published studies. We show that the new method increases the number and proportion of consumed individuals in the diet for large prey animals compared to the conventional method. CONCLUSION/SIGNIFICANCE: Our results have important implications for the interpretation of scat-based studies in feeding ecology and the resolution of human-wildlife conflicts for the conservation of large carnivores. Public Library of Science 2012-06-08 /pmc/articles/PMC3371055/ /pubmed/22715373 http://dx.doi.org/10.1371/journal.pone.0038066 Text en Wachter 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, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Wachter, Bettina
Blanc, Anne-Sophie
Melzheimer, Jörg
Höner, Oliver P.
Jago, Mark
Hofer, Heribert
An Advanced Method to Assess the Diet of Free-Ranging Large Carnivores Based on Scats
title An Advanced Method to Assess the Diet of Free-Ranging Large Carnivores Based on Scats
title_full An Advanced Method to Assess the Diet of Free-Ranging Large Carnivores Based on Scats
title_fullStr An Advanced Method to Assess the Diet of Free-Ranging Large Carnivores Based on Scats
title_full_unstemmed An Advanced Method to Assess the Diet of Free-Ranging Large Carnivores Based on Scats
title_short An Advanced Method to Assess the Diet of Free-Ranging Large Carnivores Based on Scats
title_sort advanced method to assess the diet of free-ranging large carnivores based on scats
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3371055/
https://www.ncbi.nlm.nih.gov/pubmed/22715373
http://dx.doi.org/10.1371/journal.pone.0038066
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