Why implantation of bio‐loggers may improve our understanding of how animals cope within their natural environment

Abstract

Bio‐loggers are miniaturized autonomous devices that record quantitative data on the state of free‐ranging animals (e.g. behavior, position and physiology) and their natural environment. This is especially relevant for species where direct visual observation is difficult or impossible. Today, ongoing technical development allows the monitoring of numerous parameters in an increasing range of species over extended periods. However, the external attachment of devices might affect various aspects of animal performance (energetics, thermoregulation, foraging as well as social and reproductive behavior), which ultimately affect fitness. External attachment might also increase entanglement risk and the conspicuousness of animals, leaving them more vulnerable to predation. By contrast, implantation of devices can mitigate many of these undesirable effects and might be preferable, especially for long‐term studies, provided that the many challenges associated with surgical procedures can be mastered. Implantation may then allow us to gather data that would be impossible to obtain otherwise and thereby may provide new and ecologically relevant insights into the life of wild animals. Here, we: (i) discuss the pros and cons of attachment methods; (ii) highlight recent field studies that used implanted bio‐loggers to address eco‐physiological questions in a wide range of species; and (iii) discuss logger implantation in light of ethical considerations.

Biologging of emperor penguins – attachment techniques and associated deployment performance

“…Ethical concerns raised by the use of measuring devices on wild animal are not new 28 and a recent review 117 addressed the current pros and cons on attachment issues. To ensure data is of exemplary quality from a scientific and ethical point of view, the potential deleterious effects of deployment procedures (capture-attachment-recapture) must be assessed and mitigated.…”

Modeling larval dispersal for the gilthead seabream in the northwestern Mediterranean Sea

“…More broadly, there is a crucial need to better identify where the key reproduction sites of the seabream found in the coastal lagoons of the GoL are located. If biotelemetry is now widely used to study the spatial ecology of large migratory marine species (Block et al, 2011;Hussey et al, 2015), we believe that acoustic telemetry is the best approach for a small coastal migratory fish such as the gilthead seabream in order to avoid affecting its natural behavior (Forin-Wiart et al, 2019). Acoustic telemetry is widely used to study the spatial ecology of fish (Donaldson et al, 2014;Abecasis et al, 2018) and it has already helped following the movements of seabream adults within a coastal lagoon in Portugal (Abecasis and Erzini, 2008).…”

Future trends in measuring physiology in free-living animals

“…for ECG and EEG), which would require excessive power for transmission. Subsequent removal of the device or electrode usually necessitates recapture and repeat surgery, with important ethical implications (reviewed in [61]).…”

“…Species exhibit different pharmacokinetic and pharmacodynamic responses to anaesthetic drugs, and the morbidity and mortality of veterinary anaesthesia remains orders of magnitude higher than in humans [107]. Animals may also have different responses to foreign-body insertion, which requires careful investigation and adequate mitigation [61]. There remains significant potential for sub-standard practice, despite researchers' best intentions and efforts, which the community must address head-on.…”