posted on 2023-05-22, 17:56authored byAinley, D, Woehler, EJ, Lescroel, A
The presence of sea ice has no analogue as a marine bird habitat feature in most of the world ocean outside of the high-latitude polar regions. With respect to the Southern Ocean, three species assemblages have been consistently identified among seabirds that frequent waters south of the Antarctic Polar Front (APF) as detailed from at-sea surveys around the Antarctic (Table 24.1). One assemblage is associated strictly with the presence of sea ice or with waters that within the year are covered by sea ice (ice-obligate species; see further detail later in the chapter), and the second is associated with open water and avoids sea ice (ice-avoiding species). The third assemblage, somewhat a subset of the second, includes species that mostly frequent open water but which can be found during summer within the outer portions of the sea ice field that rings the Antarctic continent (ice-tolerant species). In other words, especially for the latter group, membership can be affected by factors such as breeding phenology and distribution of nesting colonies, in which case, for example, a species may commute over sea ice to travel between a nesting colony and the open water but is not dependent on sea ice in the same sense as ice-obligate species.