Rehabilitation and release contribute to conservation efforts for threatened species. Ensuring the efficacy of these efforts requires a good understanding of the factors which determine survival and integration of released animals into wild populations. Post-release monitoring using animal-borne devices, including biologging or marking devices attached to or inserted inside animals, offers the opportunity to gain this information. The impacts of such devices on animal welfare are poorly researched. There is a growing consensus that researchers have an ethical obligation to reduce harm to animals. The well-established principal of the four Rs; replacing experimental animals, reducing the number of animals used, refining protocols to reduce suffering, and refusing unnecessary experimentation, aims to achieve this. Here, we suggest a framework for applying the four Rs to ensure the ethical use of animal-borne devices during post-release monitoring. To develop this framework, we consider the impact of the use of animal-borne devices on animal welfare and survival. The framework emphasises: i) clear definition of aims before the study begins, ii) consideration of the benefits of data obtained to conservation, iii) consideration of species and habitat specific needs iv) continued development of protocols based on feedback during the study, and v) transparency among the research and rehabilitation community (the DBSDT framework). The framework is widely applicable. As a case study, we develop a set of guidelines for the ethical use of biologging devices during post-release monitoring of ground pangolins (Smutsia temminckii).

Changes in species abundance and distribution are driven by short-term interactions between individuals and their environment, as well as by long-term shifts in climate, prey abundance, disease outbreaks and predators, acting across generations. Unfortunately, management of wildlife populations by humans has often overlooked these long-term effects. This approach has resulted in an overestimation of nature’s resilience, leading to overharvesting and contributing to the decline and extinction of species. Field studies that document species demography over sufficiently long periods to understand the drivers of change are rare but crucial for sustainable management. In our view, these datasets should be recognised as World Heritage Ecological Time Series (WHETS). To counteract biodiversity loss, it is essential to document, preserve, and develop existing WHETS. We illustrate the value of such time series using the example of the Kattegat-Skagerrak Sea Region harbour seal (Phoca vitulina).