Understanding the factors driving seabirds’ spatial and temporal distribution is important to infer the likely impact of a changing climate. At sea observational data onboard the vessels can provide such an insight into the distribution of this species. Preliminary results associated sightings with approximate positions of oceanographic features, and suggested that there is a distinct groupings with some species associated with particular features or water masses. Latitudinal transects south of Africa indicate that fronts seem to play critical roles in determining seabird assemblages.
A number of species were associated with water to the north of the subtropical convergence (and for some, immediately around it). These included prions Pachyptila spp., great-winged Pterodroma macroptera and white-headed petrels Pt. lessonii. Prions observed north of the subtropical convergence were almost exclusively Antarctic prions P. desolata, whereas Salvin’s prions P. salvini were thought to be more predominant south of the convergence. Blue petrels Halobaena ceurulea and Southern giant-petrels Macronectes giganteus were recorded from south of the subtropical convergence, but became noticeably more common south of the Antarctic Polar front. Several species were only observed close to South Africa or its continental shelf. This included species that were strictly associated with land, such as Cape cormorants Phalacrocorax capensis and Hartlaub’s gulls Larus hartlaubi, but also in this data set included species migrating from distant areas, such as yellow-nosed albatrosses Thalassarche spp, sooty shearwaters Ardenna grisea and the white-chinned petrel Procellaria aequinoctialis. Equally, there were birds associated with the Prince Edward Islands, with some, such as the Crozet shag Phalacrocorax atriceps and the Kerguelen tern Sterna virgata being strictly located there. Wandering albatrosses Diomedea exulans were also associated, as they were breeding on the islands at the time of this cruise.