Effects of back‐mounted biologgers on condition, diving and flight performance in a breeding seabird

Using a noose-pole, we caught 36 adult common guillemots rearing chicks on a natural rock ledge below the Karlsö Murre lab (8–25th June 2015) (Hentati-Sundberg et al. 2012, Evans et al. 2013). Individuals were randomly allocated to one of four groups (Fig. 1) following a controlled crossover design (Wellek and Blettner 2012): experimental guillemots (with devices) with two order groups (caught three times); full controls (caught twice); and background controls (caught once). Twelve guillemots were tagged with devices, all of which were followed for 4.3 ± 0.9 days (mean ± SD) with GPS and TDR and also for 3.5 ± 1.0 days with TDR only, with the order of deployments swapped for half the group. We additionally captured 24 control guillemots throughout the study period, five of which were full controls, caught twice, allowing their individual changes in mass to be followed, and 19 of which were captured once. The 19 background controls, together with the first capture information (i.e. prior to any potential treatment effect) for all guillemots (including the 12 experimental and five full controls), were used to infer whether there were any background colony level trends in mass. Further methods includes in article (https://doi.org/10.1111/jav.02509).