Data for: Estimation of density distribution in unmarked populations using camera traps

Reliable estimates of species distribution and density are essential to ecology. Camera traps have revolutionized wildlife monitoring, and camera-trap data are increasingly used to study animal distribution and density. We propose a general framework and present a statistical model to estimate the distribution and density of species for which individuals lack identifying marks. Numbers recorded at traps allow spatial variation in density to be modelled, while distances of detected animals from the cameras allow correction for missed animals in the detection sector, using distance sampling. We test the model by simulating a camera-trap survey of a population of single animals, and we apply the model to data from a field study of Reeves's muntjac. The simulation indicated that the estimates of population density were unbiased, and the model performed well in depicting spatial variation in density. In the field study, the model estimated that the overall population density of Reeves's muntjac was 4.1 ind/km2, and mapped its density distribution across the study area. We provide a method to estimate unmarked species' density distribution using camera-trap data. Application of the model can help investigate the distribution and density of many ground-dwelling solitary animal populations lacking individually recognizable markings. We expect our method to provide an effective means for wildlife monitoring.