Visual encounters on line transect surveys under-detect carnivore species: Implications for assessing distribution and conservation status
We compared the distribution and occurrence of 15 carnivore species with data collected monthly over three years by trained native trackers using both sign surveys and an encounter-based, visual-distance method in a well-preserved region of southern Guyana (Amazon / Guiana Shield). We found that a r...
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Published in | PloS one Vol. 14; no. 10; p. e0223922 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
Public Library of Science
30.10.2019
Public Library of Science (PLoS) |
Subjects | |
Online Access | Get full text |
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Summary: | We compared the distribution and occurrence of 15 carnivore species with data collected monthly over three years by trained native trackers using both sign surveys and an encounter-based, visual-distance method in a well-preserved region of southern Guyana (Amazon / Guiana Shield). We found that a rigorously applied sign-based method was sufficient to describe the status of most carnivore species populations, including rare species such as jaguar and bush dog. We also found that even when accumulation curves for direct visual encounter data reached an asymptote, customarily an indication that sufficient sampling has occurred to describe populations, animal occurrence and distribution were grossly underestimated relative to the results of sign data. While other researchers have also found that sign are better than encounters or camera traps for large felids, our results are important in documenting the failure of even intensive levels of effort to raise encounter rates sufficiently to enable statistical analysis, and in describing the relationship between encounter and sign data for an entire community of carnivores including felids, canids, procyonids, and mustelids. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Competing Interests: The authors have declared that no competing interests exist. Current address: Instituto Nacional de Pesquisas da Amazônia (INPA/MCTIC), Manaus, Brazil Current address: Conservation Science Group, Department of Zoology, University of Cambridge, Cambridge, England, United Kingdom These authors contributed subsets of effort equally to this work. Current address: Laboratório de Biologia da Conservação (LaBiC)–Instituto de Biociências, Departamento de Ecologia, Universidade Estadual Paulista, Rio Claro, São Paulo, Brazil Current address: Institute of Biodiversity Science and Sustainability, California Academy of Sciences, San Francisco, California, United States of America Current address: Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, Brazil |
ISSN: | 1932-6203 1932-6203 |
DOI: | 10.1371/journal.pone.0223922 |