Methodology:

A previous compilation of snow petrel breeding sites (Croxall et al., 1995) was used as the initial framework. Localities and coordinates of snow petrel breeding sites were found through an intensive search of the published literature. This was supplemented by post-1945 archived field reports, field notebooks, and maps held in the archives at the British Antarctic Survey. Unpublished observations of breeding sites in Dronning Maud Land were kindly provided by S. Descamps. Unpublished observations of breeding sites in East Antarctica were kindly provided by Australian Antarctic Science projects # 4088 and 4518.

The following environmental data were used to describe local environmental conditions at each breeding site:

Distance to the coast was calculated using High resolution vector polylines of the Antarctic coastline (v7.5) (Gerrish et al., 2022). Distance to the nearest research station was calculated from stations in CONMAP 2017 Quantarctica. Climate reanalysis data from ERA-5, Copernicus (Munoz Sabater, 2019) for the months November - March of the years 1992 - 2021 was used to calculate 30-year means of 2m temperature, total precipitation and 10m wind speed and direction. Breeding site lithology was appended from the SCAR GeoMAP (Cox et al., 2023).

Passive microwave sea ice data for the months November and February of the years 1992 - 2021 was accessed from the National Snow and Ice Data Center (NSIDC) (https://nsidc.org/data/g02135/versions/3, accessed November 2023). Distance from breeding sites to the outer ice edge contour of 15 percent concentration, and contour of 50 percent concentration were calculated for both months of each year, and then averaged over the 30 years. The area between 15-50 percent sea ice within a 700 km and 1500 km foraging range of each site was then estimated for November and February of each year, and averaged over the 30 years.

The associated Readme file also provides information on the compilation, including spatial statistics and the confirmation of the presence of the snow petrel breeding site.

Data collection:

Analysis conducted in QGIS version 3.26.2