Reduction in adverse effects of tracking devices on waterfowl requires better measuring and reporting

Abstract

Since the first studies in the mid-twentieth century, lightweight electronic tracking devices have been increasingly used to study waterfowl movements. With half a century of experience and growing sample sizes, it has become clear that the attachment of a tracking device can affect a bird's behaviour and fitness. This becomes problematic when it introduces uncertainty about whether the recorded data represent natural behaviour. Waterfowl may be particularly prone to tag effects, since many species are migratory and tracking devices can disrupt their waterproof plumage. The primary aim of this paper is to identify how tracking devices may affect waterfowl survival, migration and reproduction, and how better measuring and reporting of such effects can improve our understanding of the risks, providing a first step towards reducing their impact in future studies. We reviewed literature on electronic tracking of waterfowl to create an overview of currently recognized effects of harness-attached backpacks, implants, subcutaneous attachments and neck collars. Additionally, we analysed developments in the use of attachment methods, the weight of tracking devices relative to bird body mass, and the reporting rate of effects of tracking devices in 202 original tracking studies. We found that although the number of waterfowl tracking studies described in peer-reviewed literature has steeply increased over the past decades, reporting rates of potential effects have decreased from 65.0 to 26.5%. Meanwhile, the mean weight of the tracking devices relative to the bird's body mass remained stable around 2.0%. Major negative effects were reported in 17% of all studies and were found for all attachment methods. Overall, large differences exist in the occurrence and type of negative effects between species and studies, even if the same tracking methods were used. Inconsistent reporting of effects, lack of control groups to measure effects and incomplete descriptions of the methodology hamper the identification of factors contributing to these effects. To accomplish a reduction in adverse effects of tracking, it is necessary to improve the measuring and reporting of effects. We propose a framework for standardized reporting of methods in primary tracking studies and standardized protocols to measure effects of tracking devices on waterfowl.

Effects of harness-attached tracking devices on survival, migration, and reproduction in three species of migratory waterfowl

“…Our results are concurrent with recent reviews on the negative effects of tracking devices on birds [2,26,40]. We show that harness-attached transmitters can negatively affect survival but also pair-bonding, and thus the potential of birds to initiate breeding.…”

“…This may be caused by a change in behavior (e.g., increased time spent preening, [13]) or reduced flight maneuverability by the cross-sectional profile of the backpack tag causing additional drag [4], and perhaps not so much hunters targeting for marked geese [6]. Although our study found negative effects on return rates, our survival rates of tagged individuals were definitively higher than in some other studies [39], Harness attachments may have negative effects on survival, but are also likely to have non-lethal effects on migratory birds [26]. By using a control group from which we have individual data on migration timing gained from geolocators, we can show convincingly that harness attachments cause only a slight delay in timing of migration departure for barnacle geese.…”

“…It is challenging to test for these potential negative effects. While negative effects of tracking devices remain ubiquitous in tracking studies, reporting rates of these effects have gone down over the past decades [26]. To ensure that tracking data reflects the natural behavior of birds, it is critical to apply rigorous tests for potential effects of tracking devices and to develop attachment methods that reduce the negative effects.…”

Minimizing the impact of biologging devices: Using computational fluid dynamics for optimizing tag design and positioning

“…Finally, most existing guidelines for tag impact do not advise on appropriate tag size, placement positions or configurations (Rosen et al, ) and many are relatively naïve to the impacts of drag that are most relevant to marine and aerial applications (see Appendix for an overview). We anticipate that the reporting of drag values in future publications may help improve future guidelines and address recent requests in the literature for improved reporting of impacts (Bodey et al, ; Lameris & Kleyheeg, ) and better assessment of tag‐induced effects (such as drag) prior to deployment in the field (Lear et al, ). While we do not expect our findings to be taken up as formal guidelines, nor the use of CFD to be made compulsory, we hope that this work, and specifically our step‐by‐step guide (Appendix ), will aid the biologging community in achieving this.…”

Effects of tracking devices on individual birds – a review of the evidence

“…White et al (2013) compared the effects of external attachment with surgical implantation in a meta-analysis of 39 studies; consistent negative effects on body condition, reproduction, metabolism and survival were found with external attachment, whereas implanted devices had no consistent effects, although their use was associated with mortality resulting from the anaesthesia and surgery required for implantation. Lameris and Kleyheeg (2017) found major negative effects in 17% of 202 tracking studies of waterfowl, encompassing all attachment methods. Most recently, Bodey et al (2018) conducted a series of phylogenetically controlled meta-analyses of 214 studies incorporating control groups, finding small but significant negative effects of devices on survival, reproduction and parental care, and that foraging trips were longer in marked birds.…”