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

Author(s)

Fragoso, Jose M. V. ^{[1, 2, 3, 4]} ; Goncalves, Fernando ^{[1, 5, 6]} ; Oliveira, Luiz F. B. ^[7] ; Overman, Han ^[8] ; Levi, Taal ^[9] ; Silvius, Kirsten M. ^[10]

Affiliation

^[1] Stanford Univ, Stanford, CA 94305 - USA

^[2] Univ Brasilia, Inst Ciencias Biol, Brasilia, DF - Brazil

^[3] Calif Acad Sci, Inst Biodivers Sci & Sustainabil, San Francisco, CA 94118 - USA

^[4] Inst Nacl Pesquisas Amazonia INPA MCTIC, Manaus, Amazonas - Brazil

^[5] Univ Estadual Paulista, Dept Ecol, Inst Biociencias, Lab Biol Conservacao LaBiC, Sao Paulo - Brazil

^[6] Univ Cambridge, Dept Zool, Conservat Sci Grp, Cambridge - England

^[7] Univ Fed Rio de Janeiro, Museu Nacl, Dept Vertebrados, Rio De Janeiro, RJ - Brazil

^[8] SUNY Coll Environm Sci & Forestry, Environm & Forest Biol, Syracuse, NY 13210 - USA

^[9] Oregon State Univ, Dept Fisheries & Wildlife, Corvallis, OR 97331 - USA

^[10] Virginia Tech, Dept Forest Resources & Environm Conservat, Blacksburg, VA - USA

• Document type: Journal article
• Source: PLoS One; v. 14, n. 10 OCT 30 2019.
• Web of Science Citations: 0

Abstract

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. (AU)

• FAPESP's process: 17/24252-0 - Anthropogenic predictors of biodiversity response to forest fragmentation in the Atlantic forest
• Grantee: Fernando Henrique Martin Gonçalves
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 19/00648-7 - Extinction-driven changes on mammalian communities in the Atlantic Forest hotspots
• Grantee: Fernando Henrique Martin Gonçalves
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor