Wardrums
Rise of a new hegemony

Since their appearance, herdstalkers were the apex predators of Antarctica. They are in fact more efficient at taking down large birds, unlike geotters, which continue to fill a mesocarnivore niche. But new and unexpected competitors have recently risen from a divergent group of ducktails, which has specialized at eat meat: wardrums (clade Anserodontinae). They comprise 7 species, found across any ecoregion of Polarica.
Like all ducktails, wardrums possess false teeth; they are however more elongated and used to better grasp their prey, while their extremely rough tongue and enormous bite force (greater than any herdstalker) are their main offensive weapons to take them down. 

The smallest and most gracile species is the fisher drum (Glossodon piscivorus), a 150 cm (5 feet) tall predator which is known to hunt fish and aquatic crustaceans in the Belgrano wetlowland.
They possess a long and strong neck that is used as a lever to fastly catch their prey in the water. This behavior is usually observed during summer when this type of food becomes more abundant; in the rest of the year, the fisher drum becomes a fierce generalist that hunts any small-medium-sized vertebrate near wetlands. They are perfectly adapted to run, with a top speed of 30 km/h  (22 miles/h) on short distances.

Wardrums are on average larger than any modern herdstalker, with one of them being larger than any terror bird ever: the vojaeger (Incubodon variabilis). This frightening creature is the largest predator that Antarctica has seen in the entire Lentocene: while not being a good runner, this bird can successfully ambush large-sized ducktails. This wardrum possesses large and sharp false teeth that are used to hold their prey, while its raptorial beak helps open up carcasses. When facing large animals (like obelisks or thronghorns), the vojaeger often rips pieces of meat from its victim, usually around the legs and chest. The weakened prey will struggle to keep up with its herd, eventually dying of starvation or hemorrhages.
Despite their brutal hunting behavior, vojaegers are caring parents: this bird usually lives on its own, but social interactions are strong between neighbors and especially with its partner, with which often form a monogamous couple. Chicks are raised in large nests made of hay and feathers and can potentially stay with their parents for an entire year. Unlike large flying raptors, siblicide is a very rare occurrence in vojaeger's youngs, probably due to the great abundance of food in the breeding season and the natural low recruitment rate of the species; vojaegers are in fact k-selected species, with females rarely laying more than three eggs every year; on the other hand, chicks have very low mortality and reach sexual maturity relatively fast, after two years of age.

Vojaegers have a symbiotic interaction with a species of herdstalker: the two predators often live and hunt together in gangs, a behavior strategy that has drastically increase their hunting skill and their overall evolutionary success.