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

We review long-term patterns of tracking device use and the reporting of
the effects of such devices on individual birds. We assessed >3,400
primary references including >1,500 containing information as to
whether effects were looked for and reported. Numbers of papers published
increased at 4.4% per year. Research on foraging and energetics focussed
on seabirds while work on habitat use and dispersal was focussed mainly on
landbirds. Migration was the most common study topic overall and increased
markedly from the turn of the century in all three bird groups. The
proportion of studies reporting effects of devices on individuals declined
at > 1% per year, while the proportion of studies providing no
information on effects increased by ca. 0.7% per year. The presence of a
control group increased the likelihood of a study reporting effects, (45%
vs 33%). We modelled the probability of reporting effects separately for
three bird groups and two attachment durations. Occurrence of effects was
significantly related to attachment method (4 models), year (4 models) and
relative device mass (1 model). Invasive attachment methods were
associated with a high incidence of effects while tail and leg attachments
showed relatively few effects. Probabilities of reporting effects declined
over time and increased with relative device mass, however there was no
device mass threshold below which effects were not observed. Approaches
designed to minimize potential effects of devices on individual birds and
to improve scientific rigour have advanced substantially. Nevertheless ca.
55% of studies contained no information on potential effects and in many
more documentation was inadequate. We call for more systematic
documentation of potential effects in peer-reviewed publications to
support more rigorous science and to further improve bird welfare.