WATLAS: high throughput and real-time tracking of many small birds in the Dutch Wadden Sea

Abstract

AbstractMovement is a fundamental aspect of life and tracking wild animals under natural conditions has become central to animal behaviour, ecology, and conservation science. Data from tracked animals have provided novel scientific insights on extreme migratory journeys, mechanisms of navigation, space use, and early warning signals of environmental change. Studying movement is therefore important, particularly in systems that may be vulnerable to anthropogenic effects. Technological advancements, and chiefly the development of GPS tags, have enabled animal tracking at high spatiotemporal resolution, yet trade-offs between cost, sampling frequency, tag weight and data retrieval limit the use of GPS tags to relatively few individuals and large species. A new ‘reverse-GPS’ wildlife tracking system, ATLAS, employs an array of receiver stations that detect and localise small (∼0.6 g without battery), low-cost (∼25 euro) tags by calculating differences in the arrival time of tag signal at minimally three stations. In this study, we introduce the Wadden Sea ATLAS system (WATLAS), implemented in the Dutch Wadden Sea, the Netherland’s only natural UNESCO World Heritage Site, yet affected by a suite of anthropogenic activities, such as commercial fishing, mining, shipping, as well as sea level rise. From July 2017 to July 2021, we tracked 821 red knots, 182 sanderlings, 33 bar-tailed godwits, and 6 common terns. With four examples, we illustrate how WATLAS opens-up possibilities for studying space-use, among-individual variation in movement, and intra-specific interactions, and inter-specific (community) space use in the wild. We additionally argue that WATLAS could provide a tool for impact assessment, and thus aid nature conservation and management of the globally important Wadden Sea ecosystem.