What are geolocators?
For many years researchers at the University of Tasmania's Institute for Marine and Antarctic Studies (IMAS) have been tracking Antarctic and Southern Ocean top predators, from delicate Short-tailed Shearwaters to imposing Southern Elephant Seals, using light-level geolocators.
Geolocators are miniature tracking devices that record ambient light levels, water temperature and time. The light curve produced over the sunrise and sunset twilight period is unique to a given latitude. The time of noon is also specific to a given longitude. Collecting this data identifies the relative location of a tagged animal to within 200km. Using satellite derived sea surface temperature, with knowledge of the species’ likely travel speed, we can further constrain this area to achieve a more accurate position.