DOI: 10.5061/dryad.xksn02vg7
title: GPS tracks and behaviour detection of chick-rearing streaked shearwaters at Funakoshi Oshima Island, Japan, 2018 & 2019

description: The study of seabird behaviour has largely relied on animal-borne tags to
 gather information, requiring interpretation to estimate at-sea
 behaviours. Details of shallow-diving birds’ foraging are less known than
 deep-diving species due to difficulty in identifying shallow dives from
 biologging devices. Development of smaller video loggers allow a direct
 view of these birds’ behaviours, at the cost of short battery life.
 However, recordings from video loggers combined with relatively low power
 usage accelerometers give a means to develop a reliable foraging detection
 method. Combined video and acceleration loggers were attached to streaked
 shearwaters in Funakoshi-Ohshima Island
 (39'N,141'59''E) during the breeding season in 2018.
 Video recordings were classified into behaviours and a detection
 method was generated from the acceleration signals. Two foraging
 behaviours, surface seizing and foraging dives, are reported with video
 recordings. Surface seizing was comprised of successive take-offs and
 landings (mean duration 0.6 and 1.5s, respectively), while foraging dives
 were shallow subsurface dives (1.9s mean duration) from the air and water
 surface. Birds were observed foraging close to marine predators, including
 dolphins and large fish. Foraging detections were validated against video
 recordings (surface seizing true positive 78%, false positive 5%, foraging
 dive true positive 66%, false positive &lt;1%). The detection method
 was implemented to data from longer duration acceleration and GPS datasets
 collected during the 2018 and 2019 breeding seasons. Foraging trips lasted
 between 1-8 days, with birds performing on average 16 surface seizing
 events and 43 foraging dives per day, comprising &lt;1% of daily
 activity, while transit and rest took up 55% and 39%, respectively. This
 foraging detection method can address the difficulties of recording
 shallow-diving foraging behaviour and provides a means to measure activity
 budgets across shallow diving seabird species.
description: Experiments were carried out on breeding streaked shearwaters
 (<em>Calonectris leucomelas</em>), mean body mass, 560 ± 52 g,
 (n = 25) at Funakoshi-Ohshima Island (39'N,141'E), Japan, during
 the chick-rearing periods of August-September 2018 and August 2019. A
 total of 27 birds were captured by hand at their burrows and one tag was
 attached to each bird. 11 individuals were tagged with GPS and
 acceleration (AxyTrek) tags (Axy-Trek Marine, Technosmart, Guidonia
 Montecelio, Italy) in 2018 and 9 in 2019. Tags were attached to the
 back feathers using waterproof tape (Tesa, Hamburg, Germany) and instant
 glue (Loctite, Dusseldorf, Germany). Behaviour
 detections were generated using the method described in the related study.
 Behaviours were classed as FL (flight), Takeoff, Dive (foraging dives),
 Take-off bout (surface seizing - see article), and Unknown. Two files are
 present for each day of AxyTrek recording and are named in the format
 TagID-YYYYMMDDForageGPS or TagID-YYYYMMDDEthoTransitions. *ForageGPS files
 contain 4 columns, the datetime values, latitude, longitude, and forage
 (whether foraging behaviour was detected within 30 seconds of the GPS
 fix). *EthoTransitions files contain 2 columns, Var1 is the start times of
 the behaviours identified in column tBeh.
description: Data were split by day to ease computing of the behaviour
 detection method, therefore each tag has multiple files that make up the
 total recording duration.