Survival analysis of wildlife cameras on roads exposed to theft

Setting camera traps along roads is often necessary for ecological research and visitor management studies, yet these locations expose cameras to theft leading to substantial data losses. Measures to minimise this risk include placing cameras away from human settlements among other things. However, the effect of this and other measures on the risk of camera-trap theft is yet to be quantified. Here, we assessed the influence of gates on roads, the frequency of vehicle and human foot traffic, distance to the nearest town, and reduced visibility, on camera-trap theft risk, using data from a four-year, geographically extensive camera-trapping study in Tasmania, Australia. The dataset covered 564 camera sites operating for 316,372 days (average of 561 camera days per unit), with 112 cumulative thefts. We used Bayesian survival modelling to determine the factors that best explained theft risk. Our results showed a high initial vulnerability to theft that gradually reduced over time, with significant predictors of reduced theft risk being: (i) lower frequencies of vehicle traffic, (ii) greater distance from the nearest town, (iii) the presence of a gate, and (iv) a temporal trend likely reflecting adaptive changes to the deployment strategies used by researchers to reduce camera visibility. The frequency of human foot traffic surprisingly did not significantly elevate theft risk. Our study evidence-based insights into factors wildlife camera users should consider to mitigate theft risk on roads and provides a robust analytical framework to identify them, with application in diverse social and ecological contexts.