A new rallid radiation
The coose

Rallids are still the most biodiverse bird family (after passerids) in Antarctica, occupying any type of small niche of the icy continent, often becoming flightless. However, one clade of coot, derived from the robust-beaked coot, was able to occupy a large niche that would be left empty by ducks and razorbills of Polarica: we are talking about the coose (Alcinapteryx ameryensis) (the plural is always coose, like moose. So, stop calling them Ceese)

Coose (subfamily: Alcirallidae) is a rhea-sized bird that evolved to eat canelo trees and shrubs that, as we said in precedent pages, are highly poisonous for any antarctic vertebrate. Since canelos are mainly aquatic or riparian plant species, the coose has maintained lots of amphibious adaptations of their ancestors: for example, their feet are still lobed and are proportionally large and flattened, helping the coose to efficiently swim in rivers and lakes. They are also known to eat lots of algae and submerged plants and occasionally crustaceans during summer, while in winter evergreen canelos become the major part of their diet, since other types of vegetation are rare or not available. Both sexes possess a long crest on their head, used to open their way in dense reeds and to intimidate rivals during the mating season. 

Coastal wetlands are the favored coose habitat and they are extremely important for their dispersion since wetlands are more frequent there. Coasts are the most humid areas of Antarctica since annual precipitations are relatively high for a polar environment (>500 mm). The presence of large lagoons and river deltas also increases the available habitats for this species.