Processed tracking data of Southern Giant Petrels during breeding activity in Harmony Point, Nelson Island, between 2021 and 2023

Processed GPS data for 36 Southern Giant Petrels (Macronectes giganteus) in December and January of 2021/22 and 2022/23 breeding season in Harmony Point (62°17′60″ S, 59°10′60″ W), Nelson Island, Maritime Antarctic Peninusula. All individuals had active nests. Bill size and tarsus length for 50 southern giant petrels ringed in the area.

Between 2021 and 2023 50 breeding individuals were captured on the nest, following methods and protocols previously approved (https://zenodo.org/doi/10.5281/zenodo.10640094). For capture, one researcher approached the colony, while the others remained at a distance, preferentially out of sight of the birds. Response behavior to the approaching researcher was used as a proxy for capture selection, for instance, animals that regurgitate or stand on the nest exposing the eggs when the researcher approaches are more likely to leave the nest or might take longer to return to the nest after releasing, increasing the risk of breeding failure (Krüger et al. in prep). Therefore, animals displaying those behaviors were not captured. Before capture, the egg was gently removed from below the bird, covered in thermal tissue and put inside a box, for protection from cold and predation. Then the bird was captured by hand and taken to the site where other two researchers were waiting. Animals had their eyes covered with a head hood. All captured animals were ringed with stainless steel bands (rings), preferentially both animals from the same nest each season. All captured animals had bill and tarsus measured with calipers. Bill was used to determine sex, since males have larger bills with no overlap of measures with females. After release back to the nest, behavioral status of the animal was observed, and after the animal remained sat at the nest, the egg was placed back.

GPSs were deployed on the back of the birds using 3M Extreme Hold Duct Tape 2835-B (1.88 inches) and Loctite glue.  In 2021/22 and 2022/2023 seasons 30 and 20 birds were tagged with GPSs, respectively. In 2021/22, 4 females lost the GPS, and in 2022/23 one male and one female lost the GPS. Therefore there was tracking data for 26 and 18 animals, respectively.  Eight animals were repeated in both seasons, totalizing 36 animals tracked in the two seasons. CatLog-P Gen 2 epoxy cased GPSs loggers (Perthold Technology, 50g) and Sputnik XAIS GPSs (Sextant technology, 70g) were used. Southern Giant Petrel weight varies between 4 kg and 6 kg, therefore the heavier instrumentation on the lighter birds would represent less than 2% of body weight, percentage which is accepted to have no significant effect on large procellariforms . Loggers were configurated to record one geographical fix each 5 minutes, and were recovered from the birds after 2 to 4 weeks.

See https://github.com/drlucaskruger/SouthernGiantPetrel_Movements_and_Individual_Size for codes.

This study was funded by INACH (Programa Áreas Marinas Protegidas 24 03 052) and ANID – Programa Iniciativa Milenio – ICN2021_002 (BASE).