GNSS-based animal tracking: An indirect approach

Global Navigation Satellite System (GNSS) technology has revolutionised the way 3-dimensional positions are determined on and above the surface of the Earth. Over the last two decades or so, GNSS has evolved into a vital positioning tool for a wide range of applications reliant on spatial data. One such application is the tagging and tracking of animals to better understand animal behaviour and ecology (the study of the relationships that living organisms have with respect to each other and their natural environment). Monitoring animal populations is also necessary for conservation purposes and to limit negative effects on the human population, particularly in an era of human expansion into traditional animal habitats. GNSS technology has allowed significant advances in this field by providing the ability to obtain accurate, regular and frequent estimates of the changing distributions of many rare animal species. However, employing conventional GNSS-based animal tracking methods to study species that spend most of their time in treetops is extremely difficult because the tree canopy regularly causes extended periods of complete GNSS signal loss. This paper proposes an indirect GNSS-based approach for the tracking of tree-dwelling animals. This involves tracking the prey rather than the predator in order to map the animal population in a particular area. Using a case study on drop bears, it is shown that this method can be used to effectively estimate the number of animals present in the area and provide valuable insights into its hunting behaviour.