DOI: 10.5061/dryad.tqjq2bw5t
title: Migratory and winter movements of Arctic Alaska breeding Sabine’s Gulls (Xema sabini)

description: The Sabine’s Gull (Xema sabini) is a pelagic, Arctic-breeding species with
 a circumpolar breeding distribution. Little is known about migration
 routes for Sabine’s Gulls breeding in the Alaskan Arctic. We tagged
 Sabine’s Gulls on their northern Alaska breeding grounds to identify
 migration routes and wintering areas and compare geolocators and GPS
 pinpoint tags for use on small-bodied gulls. Twelve geolocators were
 deployed in northern Alaska in 2011 (Colville River Delta) of which four
 were recovered, and five GPS pinpoint tags in 2021 (Qupaluk). Although the
 GPS pinpoint tags provided more accurate locations allowing for
 finer-scale habitat evaluation, and did not require recapture of birds,
 the overall coverage provided by geolocators was superior in this study
 given the constraints of the number of locations GPS pinpoint tags can
 record. Broadly, the four (one tag failed) tracked Sabine’s Gulls migrated
 away from the breeding grounds as expected, passing along the west coast
 of Alaska and south along the west coast of the Americas to winter in the
 Humboldt Current off the coast of Peru. Our tracked gulls used the same
 migratory staging and wintering areas as did Sabine’s Gulls breeding in
 the Canadian Arctic (Davis et al., 2016). Such reliance on specific marine
 areas presents risks from climate-related changes or ecological damage to
 those areas.
description: We deployed Mk12 (British Antarctic Survey) light-level
 geolocators (&lt;1g) at two sites in northern Alaska; the Colville
 River Delta (Anachlik Island; 70°23’N, 151°29’W), and northeast of
 Teshekpuk Lake (Qupaluk; 70°40’N, 152°43’W). In the summer of 2011, we
 captured 12 adult Sabine’s Gulls on Anachlik Island (the site of a
 homestead), using either a whoosh net or cage trap placed at a feeding
 station, and tagged them with Mk12 (British Antarctic Survey) light-level
 geolocators (&lt;1g). In the summer of 2021, we captured five adult
 Sabine’s Gulls on their nests with a bownet at Qupaluk (remote area with
 no permanent human presence) and equipped them with 4g Lotek Argos
 PinPoint 75 tags using leg-loop harnesses with 1.9mm Teflon ribbon, and
 copper crimps (&lt; 0.03 % of total body weight). Tags were programmed
 to take a GPS point every two days from 15 August to 15 November, and then
 one point every five days until the batteries died.
description: # Migratory and winter movements of Arctic Alaska breeding Sabine’s Gulls
 (Xema sabini) 
 SAGU_Argos_locations contains locations of the SAGU tagged with Lotek
 Argos PinPoint 75 tags. The locations were all PTT locations, no GPS
 locations were transmitted. Points generated with unsuccessful satellite
 fix were excluded. We only used PTT locations derived from &gt; 4
 satellite transmissions (i.e., location classes 0, 1, 2, and 3; Douglas
 *et al.* 2012). ## Description of the data and file structure
 SAGU_Argos_locations.CSV: This the PTT data. Has 12 columns "Platform
 ID No." = id of transmitter, "Platform" is blank, "Prg
 No" is just the project name, "Pass dur. (s)" = the seconds
 the satellite pass took, "Msg date" = date location was
 transmitted, "Sat." =Satellite id, "alarm",
 "Format name". were included by ARGOS but are not useful,
 "loc. date" = date of the locations, "Longitude" and
 "Latitude" are longitude and latitude, "Loc. quality"
 is the location class. SAGU_calibration_data. csv: calibration data for
 geolocators, 7 columns. "Geo.number"= ID,
 "deploy.longitude" and "deploy.latitude' are the
 longitude and latitude at which geo was deployed.
 "start.calibration" and "stop.calibration" are the
 start and stop dates of calibration. "longitude.calibration" and
 "latitude.calibration" are the longitude and latitude of
 calibration SAGU_geo_locations.csv: Geolocator locations, four columns.
 "Median. longitude" and "median.latitude" are the
 longitude and latitude. "date" is the date, "tag "is
 the ID of the transmitter. SAGU_920.lig, SAGU_922.lig, SAGU_924.lig, and
 SAGU_926.lig, are the raw light datafiles from the geolocators.