Spatial Distribution, Species Composition, and Number of Seabirds in the Argentine Basin, Drake Passage, East of Antarctic Peninsula, and Powell Basin in January–March 2020

Results of observations of seabird occurrence during cruise 79 of the R/V “Akademik Mstislav Keldysh” in January, February, and early March 2020 are presented. We recorded 35,851 seabirds, 20,116 of them were identified to the species level, and a total of 43 species were recorded. The observed occurrence of seabirds in the ocean was correlated to a number of environmental parameters: in January, almost all species preferred “good weather”, that is, higher air temperatures, lower humidity and, in some species, high air pressure. In February, a number of species maintained these correlations, but several species, in particular, Black-browed Albatross, Antarctic Skua, Cape Petrel, and Southern Fulmar revealed correlations opposite to the cited environmental parameters. They were mainly encountered during low air temperature and high humidity. This probably indicates that the birds found adequate foraging areas under these meteorological conditions. Several species (e.g., Antarctic Petrel, Antarctic Skua) were observed within regions with specific sea depths. The occurrence of most birds from January to February varied in the regions with different depths. Unlike marine mammals, several seabird species formed uniform distribution of occurrence along the vessel route. The Black-browed Albatross and the Southern Giant Petrel maintained this distribution pattern during both months of the study. The mathematical evaluation of distributions together with a map analysis points to the competition between species or, possibly, in addition, intraspecies competition (probably for food) among these two species.