Deployment and recovery of geolocator devices
Geolocators (seven BAS Mk18-L, and one Mk14) were deployed on both legs
of four adult puffins during the 2010 summer breeding season on Skomer
Island, Wales (51.737N, 5.297W). Single geolocators (31 Biotrack
(2012)/Lotek (2020) Mk4083 and 12 BAS Mk18 (2010)) were deployed on 40
adult puffins during the breeding season in 2010, 2012 and 2020 on
Skellig Michael, Ireland (51.771N, 10.539W). Birds at both colonies were
captured during chick-rearing either using purse nets at burrow
entrances or by hand from the burrow, weighed and fitted with
geolocators before being released back to their burrow. Capture and
handling times were kept to a minimum. Geolocators were attached to a
coloured plastic ring fitted around the tarsus, with total deployment
weight (devices plus leg ring and cable tie attachment) always
< 2% body mass, under 6g for dual-equipped loggers, and under
3g for single-equipped loggers. These devices measured light every
minute in 6-bit units from 0 (light is below civil twilight, sun
> ~ 6 degrees below the horizon) to 64 (sun
is well above the horizon) and saved the maximum light level sampled in
5-minute intervals, or 10-minute intervals for the single Mk14 logger
used. Saltwater immersion data were sampled every 3 seconds as binary
units of 0 (dry) or 1 (wet) and the number of wet samples in 10-minute
intervals were saved as values between 0 (all dry) or 200 (all wet).
Devices were recovered from birds during the subsequent breeding
seasons. All work was carried out under licence from the British Trust
for Ornithology (CO/6143, C/5311), with work in Ireland further licenced
by the National Parks and Wildlife Service (06/2020, C41/2020, 26/2010,
C051/2011, C116/2012, C039/2013, 11/2013). Attachment of dual-equipped
geolocators was granted ethical approval by the British Trust for
Ornithology Unconventional Methods Technical Panel, with ethical
approval for handling and tagging in Ireland also approved by the
University College Cork Animal Ethics Committee. All analyses were
performed using R version 4.1.2 (R Core Team, 2021), and all code to run
these analyses are available online
(github.com/JamieHDarby/puffin_moult).