An evaluation of camera trap performance – What are we missing and does deployment height matter?

Abstract

The camera trap is a powerful research tool that has a wide range of ecological applications and facilitates monitoring over large spatial and temporal scales. To improve the reliability of camera trap studies and provide more knowledge on camera performance, we evaluated three aspects of camera traps that researchers should consider -camera height, blank images and missed detections. We deployed 20 camera stations, each consisting of one low camera (0.6 m) and two adjacent high cameras (3 m). We tested for differences in detection rates and blank images between camera heights. We calculated missed detections using the two high cameras and used a subset of cameras (n = 14) to examine whether missed detections were caused by late triggers or failed triggers. We found that placing cameras high to minimize theft and damage did not influence detection rates. There were, however, more blank images which can increase the time required for analysis. These blank images increased as temperature increased. Missed detections were primarily the result of failed triggers and increased as species size decreased. Failed detections are particularly significant for distribution surveys of low-density species. Detection at the camera is imperfect, even when working with larger species.

Michigan ZoomIN: validating crowd-sourcing to identify mammals from camera surveys

“…Such variation in accuracy by species may reflect differences in capturing high quality images due to camera placement. As the optimal height for most mesocarnivores is 2-3 feet off the ground (Jacobs and Ausband 2018), smaller or larger bodied species would only be partly captured, which may create more difficulty for users completing identifications.…”

Animal detections increase by using a wide-angle camera trap model but not by periodically repositioning camera traps within study sites

“…During wildlife studies, camera traps are typically stationary within sites for the entire study period (e.g. Jacobs and Ausband 2018;Moore et al 2020). If animals move through the habitat randomly, without giving preference to any particular features, animal detection rates should not be affected by camera trap location.…”

Optimising camera trap height and model increases detection and individual identification rates for a small mammal, the numbat (

“…Camera traps in lower positions were found to be more effective by , who investigated instalment heights of 90 cm and 350 cm (targeting wild dogs, foxes and feral cats), and by Swann et al (2004), testing camera traps at 20 cm and 120 cm (targeting warm water bottles and a human mimicking animal movement). While Newey et al (2015) had better detection rates from camera traps in higher positions (120 cm versus 60 cm) when targeting sheep, Jacobs and Ausband (2018) had inconclusive results from camera traps at 60 cm and 300 cm targeting a variety of species native to Idaho, USA. In these studies, at least one of the compared camera heights substantially exceeded 50 cm, making results inconclusive for small species.…”

“…Camera traps are increasingly used to detect and monitor wildlife for conservation management (Rowcliffe and Carbone 2008;Burton et al 2015;Meek et al 2015b) so it is important to position cameras carefully to obtain robust data and to choose the most effective camera model Jacobs and Ausband 2018;Apps and McNutt 2018a). Motion-activated camera traps with passive infrared (PIR) sensors trigger when objects (e.g.…”