Random versus Game Trail-Based Camera Trap Placement Strategy for Monitoring Terrestrial Mammal Communities

PLoS One. 2015 May 7;10(5):e0126373. doi: 10.1371/journal.pone.0126373. eCollection 2015.

Abstract

Camera trap surveys exclusively targeting features of the landscape that increase the probability of photographing one or several focal species are commonly used to draw inferences on the richness, composition and structure of entire mammal communities. However, these studies ignore expected biases in species detection arising from sampling only a limited set of potential habitat features. In this study, we test the influence of camera trap placement strategy on community-level inferences by carrying out two spatially and temporally concurrent surveys of medium to large terrestrial mammal species within Tanzania's Ruaha National Park, employing either strictly game trail-based or strictly random camera placements. We compared the richness, composition and structure of the two observed communities, and evaluated what makes a species significantly more likely to be caught at trail placements. Observed communities differed marginally in their richness and composition, although differences were more noticeable during the wet season and for low levels of sampling effort. Lognormal models provided the best fit to rank abundance distributions describing the structure of all observed communities, regardless of survey type or season. Despite this, carnivore species were more likely to be detected at trail placements relative to random ones during the dry season, as were larger bodied species during the wet season. Our findings suggest that, given adequate sampling effort (> 1400 camera trap nights), placement strategy is unlikely to affect inferences made at the community level. However, surveys should consider more carefully their choice of placement strategy when targeting specific taxonomic or trophic groups.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Environmental Monitoring*
  • Mammals / physiology*
  • Photography*
  • Tanzania

Grants and funding

This work was supported by a UK Natural Environment Research Council (www.nerc.ac.uk/) grant NE/J016527/1 to TC, and by grants from the Recanati-Kaplan Foundation, Riverbanks Zoo and Garden (www.riverbanks.org/), SeaWorld Busch Gardens (seaworldparks.com/en/buschgardens-tampa/) and St Louis WildCare Insitute (www.stlzoo.org/conservation/) to AJD. The Zoological Society of London, represented by JMR and CC, contributed towards fieldwork living expenses. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.