DOI: 10.5061/dryad.hqbzkh1dm
title: Effects of back‐mounted biologgers on condition, diving and flight performance in a breeding seabird

description: Biologging devices are providing detailed insights into the behaviour and
 movement of animals in their natural environments. It is usually assumed
 that this method of gathering data does not impact on the behaviour
 observed. However, potential negative effects on birds have rarely been
 investigated before field‐based studies are initiated. Seabirds which both
 fly and use pursuit diving may be particularly sensitive to increases in
 drag and load resulting from carrying biologging devices. We studied
 chick‐rearing adult common guillemots (Uria aalge) equipped with and
 without back‐mounted GPS tags over short deployments of a few days.
 Concurrently guillemots carried small leg‐mounted TDR devices (time‐depth
 recorders) providing activity data throughout. Changes in body mass and
 breeding success were followed for device equipped and control guillemots.
 At the colony level guillemots lost body mass throughout the chick‐rearing
 period. When‐equipped with the additional GPS tag, the guillemots lost
 mass at close to twice the rate they did when equipped with only the
 smaller leg‐mounted TDR device. The elevated mass loss suggests an impact
 on energy expenditure or foraging performance. When equipped with GPS tags
 diving performance, time‐activity budgets, and daily patterns of activity
 were unchanged, yet dive depth distributions differed. We review studies
 of tag‐effects in guillemots (Uria spp.) finding elevated mass
 loss and reduced chick‐provisioning to be the most commonly observed
 effects. Less information is available for behavioural measures, and
 results vary between studies. In general, small tags deployed over several
 days appear to have small or no measurable effect on the behavioural
 variables commonly observed in most guillemot tagging studies. However,
 there may still be impacts on fitness via physiological effects and/or
 reduced chick‐provisioning, while more detailed measures of behaviour
 (e.g. using accelerometery) may reveal effects on diving and flight
 performance.
description: 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).
description: File descriptions
 capture_info_all.csv Capture details for all
 guillemots, includes capture date, body mass, and experimental
 group.<br> Experimental group (TYPE), has control (guillemots caught
 once), contol2 (guillemots caught twice), device (those with
 devices).<br> Capture - capture occasion (1, 2, or 3).
 capture_info_deviced.csv Capture details for
 guillemots that had devices deployed. Has same information as
 capture_info_all.csv with addition of chick hatch date and age.<br>
 bouts_all.csv<br> Dive bout level information. Includes key dive
 bout paramaters. Includes calculated sea surface temperature pre-bout (see
 article for details). dives_all.csv
 File contains all recorded dives, with summary information for
 each dive.<br> Headings provide variable name and unit.<br>
 Includes key extracted metadata used in the analysis (sun elevation, day
 period).<br> Several variables allow connecting with other files
 (e.g. ring_number, TDR_deployment_id, dive_bout_id)
 time_activity_budget.csv Time activity budget
 information for guillemots, derived from TDR data. Includes proportion of
 each day spent diving (dive_time_p), on post dive intervals per day
 (pdi_time_p). Also total time for each activity in seconds per day and
 broken down by night and day time (e.g. dive_time_total_day).