A comparison of vertical and horizontal camera trap orientations for detection of potoroos and bandicoots

Camera traps are increasingly used to monitor wildlife that is otherwise difficult to study. Traditionally, camera traps are set aimed horizontally towards a scent lure, capturing images of animals as they move past. A vertical camera orientation is also being used, whereby the camera lens and sensor face vertically down towards the scent lure, capturing images from above. We aimed to compare detection of southern brown bandicoots and long-nosed potoroos by camera traps set horizontally, to those set vertically. We also considered the number of false triggers and ease of species identification. Over 21 nights, we monitored 18 camera stations, each consisting of one PixController Inc. DigitalEye (TM) 7.2 camera aimed horizontally and one vertically, towards the same scent lure. We used PRESENCE (Version 3.0 (Beta)) to estimate detection probabilities for the two species, comparing a null model to a model with camera orientation as a covariate affecting probability of detection. Detection probabilities for both species was 2-5 times higher by vertical than by horizontal cameras, with no significant difference in false triggers. Vertical cameras also increased case of species identification. Vertical camera orientation is shown to be superior in our study system, providing a valid alternative method.