Light-level geolocation in polar regions with 24-hour daylight

Solar geolocation data loggers are simple tracking devices that record ambient light levels for the purpose of estimating locations and thereby reconstructing animal movement trajectories. Despite the disadvantages of these archival tags over GPS and other satellite-linked tracking devices, which mainly concern their low spatial and temporal precision, geolocators have been proven to be extremely useful tools. Their low weight (<0.5 g) and relatively low cost broadens the range of species that can be tagged (Bridge et al. 2011) as well as enabling larger sample sizes to be gathered.