A hoofpole duality

Hoofpoles are ungulate birds mostly adapted to open habitats, which rapidly diversified 10 million years ago, outcompeting all terrarider species. However, the relentless cold is now becoming too severe for even these resilient creatures. Of the 15 species and 7 genera that once thrived 10 million years in the past, only two species from two genera remain today. One of the two, despite the slow worsening of the antarctic climate, is not currently at risk of extinction; this species, called tundra hoofpole (Speroniungulatum nanus), has a nearly cosmopolitan range in Sanctuary Peninsula, being found even in the mossy environment of Greenrock. This light-built  yet tall species is still capable of short flights and survives the harsh environment by consuming any available plant matter and insects. It's a very social species and it can forms herds of over 200 individuals, often seeking protection near the far smaller herds of muskox tramplerats. These birds possess a long head crest that can goes from red to yellow and two long spurs on its feet used for defensive purpose.

The other species, the erosion-pole (Opiumavis leuca), is confined to few areas of Follia Plateau. This giant flightless bird has evolved to feed on anything viable, making it one of the most carnivorous hoofpoles in Antarctica, capable of active hunting. Despite this, it is not among the top predators of the Plateau, as its animal prey includes only small to medium vertebrates such as small terrestrial birds, mammals, eggs, lizards, and carrion. The largest observed prey was a young poop trenchcrawler, weighing 15 kg. Like bears, their diet varies greatly with the seasons. During summer, most of their food intake consists of plant matter and invertebrates. The long beak is used for both attacking and defending, with a small hook at the end facilitating the consumption of carrion, a crucial food source during winter for this species. Their tall stature aids in kleptoparasitizing other predators, which rarely stand their ground against this 2.5-meter-tall bird. Unlike other hoofpoles, the erosion-pole possesses extremely large and strong legs and hooves, necessary to support its great weight of over 200 kg and to dig the ground in search of mammal dens and roots.

Past and Present

Tundra hoofpoles, like other large vertebrates, suffered a significant decline during the Continental Crisis, but rebounded rapidly after the increase in productivity of the Follia Plateau. Actually, they are the most abundant "megafauna" of Antarctica, numbering over 200,000 individuals, with no signs of significant bottlenecks issues. On the other hand, the erosion-pole experienced a sharp decline during the continental crisis, with its population dropping to just 2,000 individuals. Unable to recover genetically enough its numbers despite the increased productivity of its habitat, the erosion-pole eventually entered the extinction vortex: now, it's believed that no more than 400 erosion-poles are alive, and the increase competition of another species, who has taken advantage of the rarefaction of this big bird, has officially extinguished any chance of recovering.
Being an obligate omnivore is advantageous when resources are abundant, but the tundra is far from being a resource-rich habitat, especially during the long, brutal antarctic winters. An analogous situation in the Holocene would be the wild boar, a generalist and successful omnivore that can thrive in various environments but struggles in the resource-scarce northernmost areas of Eurasia.
Despite its past success, the slow but steady cooling trend spells an inevitable doom for the erosion-pole. As the ice continues its relentless march, it will eventually encroach upon and cover most of the Sanctuary Peninsula, leaving no refuge even for the adaptable tundra hoofpoles.
The ice shows pity for none, and the fate of these remarkable birds hangs in the balance as the environment they once dominated transforms into an unforgiving, icy wasteland.