10.5061/DRYAD.GB5MKKWPF
Halpin, Luke
0000-0003-4108-0871
Monash University
Ross, Jeremy
0000-0001-7518-5845
University of Oklahoma
Ramos, Raül
0000-0002-0551-8605
University of Barcelona
Mott, Rowan
Monash University
Carlile, Nicholas
Department of Planning and Environment
Golding, Nick
University of Melbourne
Reyes-González, José Manuel
University of Barcelona
Militão, Teresa
0000-0002-2862-1592
University of Barcelona
De Felipe, Fernanda
0000-0003-3131-3563
University of Barcelona
Zajková, Zuzana
0000-0002-7540-3651
University of Barcelona
Cruz Flores, Marta
0000-0001-9905-4727
University of Barcelona
Saldanha, Sarah
University of Barcelona
Morera-Pujol, Virginia
University of Barcelona
Navarro-Herrero, Leia
University of Barcelona
Zango, Laura
University of Barcelona
Gonzalez-Solis, Jacob
0000-0002-8691-9397
University of Barcelona
Clarke, Rohan
0000-0002-6179-8402
Monash University
Double-tagging scores of seabirds reveals that light-level geolocator
accuracy is limited by species idiosyncrasies and equatorial solar
profiles
Dryad
dataset
2021
FOS: Biological sciences
archival tags
solar geolocation
animal tracking
sea-surface temperature
FLightR
probGLS
Australian Government
https://ror.org/0314h5y94
University of Barcelona
https://ror.org/021018s57
APIF‐2012
2021-08-24T00:00:00Z
2021-08-24T00:00:00Z
en
https://doi.org/10.1111/2041-210X.13698
https://doi.org/10.5281/zenodo.5241023
80816940 bytes
11
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Light-level geolocators are popular bio-logging tools, with advantageous
sizes, longevity, and affordability. Biologists tracking seabirds often
presume geolocator spatial accuracies between 186-202 km from
previously-innovative, yet taxonomically, spatially, and computationally
limited, studies. Using recently developed methods, we investigated
whether assumed uncertainty norms held across a larger-scale, multispecies
study. We field-tested geolocator spatial accuracy by synchronously
deploying these with GPS loggers on scores of seabirds across five species
and 11 Mediterranean Sea, East Atlantic and South Pacific breeding
colonies. We first interpolated geolocations using the geolocation package
FLightR without prior knowledge of GPS tracked routes. We likewise applied
another package, probGLS, additionally testing whether sea-surface
temperatures could improve route accuracy. Geolocator spatial accuracy was
lower than the ~200km often assumed. probGLS produced the best accuracy
(mean ± SD = 304 ± 413 km, n = 185 deployments) with 84.5% of GPS-derived
latitudes and 88.8% of longitudes falling within resulting uncertainty
estimates. FLightR produced lower spatial accuracy (408 ± 473 km, n = 171
deployments) with 38.6% of GPS-derived latitudes and 27% of longitudes
within package-specific uncertainty estimates. Expected inter-twilight
period (from GPS position and date) was the strongest predictor of
accuracy, with increasingly equatorial solar profiles (i.e., closer
temporally to equinoxes and/or spatially to the Equator) inducing more
error. Individuals, species and geolocator model also significantly
affected accuracy, while the impact of distance travelled between
successive twilights depended on the geolocation package. Geolocation
accuracy is not uniform among seabird species and can be considerably
lower than assumed. Individual idiosyncrasies and spatiotemporal dynamics
(i.e., shallower inter-twilight shifts by date and latitude) mean that
practitioners should exercise greater caution in interpreting geolocator
data and avoid universal uncertainty estimates. We provide a function
capable of estimating relative accuracy of positions based on
geolocator-observed inter-twilight period.