Passerines are the most biodiverse group of birds in Antarctica. It comprises at least 9 species of all-year-round birds of two separate lineages: the antarctic tyrant and the pipit (Anthus sp.).

One of the tyrant descendants has become one of the largest perching birds ever, with extremely robust legs and feet less useful to perch on shrubs, but functional for digging up nests underground and running. We are talking about the False ptarmigan (Pernicipasser pulchri). It can weigh up to 1 kg (2.2 lb) and possess strong muscle jaws and short beaks similar to its ancestor, but its diet has become more buds and fruit reliant recently. Furthermore, large size helps these birds to cut branches of trees more effectively and to digest more cellulose thanks to a longer intestine and cecum. Despite being able to fly, the false ptarmigan prefer to walk and run, especially because its flying predators are faster than him. If threatened, this species will run in its burrow, which can be over 10 meters long (33 feet). They often graze in small flocks near titanic mallards' harems, eating uproot trees and their semi-digested feces.

The pipit clade instead consists of two resident species, occupying two separate niches: the variable pipit and the diving pipit. While both of the species are mainly insectivorous, the variable pipit (Geoanthus criophylus) hunts insects on the ground, while the diving pipit (Limnanthus limnanthus) have adapted to hunt aquatic arthropods in rivers and lakes. When winter approaches, the variable pipit becomes nearly completely herbivorous, eating fruits and seed and sometimes ripping off a piece of meat from carrions. Conversely, the diving pipit maintains an insectivorous diet, diving and hunting in non-frozen rivers and lakes.