Visual encounters on line transect surveys under-detect carnivore species: Implications for assessing distribution and conservation status

Autoři: Jose M. V. Fragoso aff001;  Fernando Gonçalves aff001;  Luiz F. B. Oliveira aff002;  Han Overman aff003;  Taal Levi aff004;  Kirsten M. Silvius aff005
Působiště autorů: Stanford University, Stanford, CA, United States of America aff001;  Departamento de Vertebrados, Museu Nacional, UFRJ, RJ, Brazil aff002;  Environmental and Forest Biology, State University of New York-College of Environmental Science and Forestry, Syracuse, NY, United States of America aff003;  Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR, United States of America aff004;  Department of Forest Resources and Environmental Conservation, Virginia Tech, Blacksburg, VA, United States of America aff005
Vyšlo v časopise: PLoS ONE 14(10)
Kategorie: Research Article


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.

Klíčová slova:

Carnivora – Cryptic speciation – Forests – Jaguars – Otters – Vertebrates – Carnivory – Pumas


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