Animal tag technology keeps coming of age: an engineering perspective

Abstract

Animal-borne tags (biologgers) have now become extremely sophisticated, recording data from multiple sensors at high frequencies for long periods and, as such, have become a powerful tool for behavioural ecologists and physiologists studying wild animals. But the design and implementation of these tags is not trivial because engineers have to maximize performance and ability to function under onerous conditions while minimizing tag mass and volume (footprint) to maximize the wellbeing of the animal carriers. We present some of the major issues faced by tag engineers and show how tag designers must accept compromises while maintaining systems that can answer the questions being posed. We also argue that basic understanding of engineering issues in tag design by biologists will help feedback to engineers to better tag construction but also reduce the likelihood that tag-deploying biologists will misunderstand their own results. Finally, we suggest that proper consideration of conventional technology together with new approaches will lead to further step changes in our understanding of wild-animal biology using smart tags. This article is part of the theme issue ‘Measuring physiology in free-living animals (Part II)’.

Diving physiology of marine mammals and birds: the development of biologging techniques

“…Future advances that would expand research in these areas include improved attachment techniques, multisensor biologgers, decreased size of sensors and reduced drag of biologgers. Additionally, because biologging studies allow for the collection of high-resolution data, often resulting in extremely large datasets, innovation in software analysis techniques may uncover new patterns or cross-sensor relationships [148]. Much like the P O 2 and the NIRS cerebral oxygen sensors described above, many advances in sensor technology will probably come from sensors developed for human health, including wearable biosensors.…”

Heart rate as a measure of emotional arousal in evolutionary biology

“…birds, there are additional ethical considerations to be made regarding to the weight of the device. To minimize ethical risks of prolonged invasive measuring techniques, robust statistical methods to analyse the collected data are needed, which can help to refine the study design in accordance with the 3Rs (reduce, refine and replace) [118,119]. Next to ethical considerations, different devices also differ in their price range and method of actual heart rate recording.…”

Future trends in measuring physiology in free-living animals

“…In addition, as batteries become physically smaller, they tend to be less efficient in terms of energy per unit of mass, as the external casing is a larger percentage of total battery mass. Thus, future advances in increasing the quantity of data, the lifetime of devices and reducing detrimental effects on tagged animals is likely to be driven by increases in power use efficiency, rather than jumps in emerging battery technology [83]. Generally, physiologging devices record huge volumes of original sensor data and use fairly unsophisticated first-level evaluations of the logged data to calculate, for example, heart rate, which is then stored.…”

“…Biologging has fast become its own discipline within animal biology, accelerated by advances in sensor technology, miniaturization and analytical tools. Each development step has followed major advancements in human-focused, consumer-driven technologies [111], such as advancements in the cellular phone industry driving those in solid-state technology and power efficiency [83] and the miniaturisation of sensor types (e.g. video cameras).…”