Effective detection methods for medium-sized ground-dwelling mammals: A comparison between infrared digital cameras and hair tunnels

Abstract

Context Conservation planning for threatened species depends on improved knowledge of the whereabouts of critical populations and thus the development of optimal detection methods. Aims To compare the effectiveness of infrared cameras and hair tunnels for detecting small to medium-sized ground-dwelling mammals in south-eastern Australian forests. Methods Reconyx PC90 cameras were paired with Handiglaze hair tunnels at 110 stations in south-eastern New South Wales. All devices were baited using rolled oats, peanut butter and pistachio essence and left in situ for a minimum duration of 30 days. Camera detection data were analysed for the first 15 and 30 days, whereas hair-tunnel detection data were analysed for the entire duration of deployment. Linear mixed models with site as a random effect and device as a fixed effect were developed for mammal species richness. Linear mixed logistic regression models for binary data were developed for detection probabilities of five taxa of interest, namely, Isoodon, Perameles, Potorous, Trichosurus and Wallabia. Key results Hair tunnels detected eight mammal species, whereas cameras detected 18 species. Modelled detection rates using cameras were 3.160.21 species per site after 15 days and 4.240.23 species per site after 30 days, whereas hair tunnels detected 0.340.21 species over the entire deployment. Cameras were therefore approximately 912 times better at measuring mammal richness than were hair tunnels, depending on survey duration. In all calculations, the probability of detecting the five taxa of interest was significantly greater using cameras than using hair tunnels. Conclusions Infrared cameras and hair tunnels offer ethical advantages over direct detection methods such as cage trapping for small to medium-sized ground-dwelling mammals. Cameras also offer practical benefits because they work for protracted periods, without frequent checking by field researchers. Cameras are more effective at detecting a wide range of species than are hair tunnels and are significantly better for detecting the taxa we examined. Unlike hair tunnels, cameras sometimes allow for the identification of individual animals, and provide information about frequency of habitat use, reproductive status and aspects of behaviour. Implications On a unit by unit basis, infrared cameras are a far more efficient way to census a broad spectrum of ground-dwelling mammals than are hair tunnels.