Geotters from Polarica
While herdstalkers still maintain large predator niches, geotters have become the most successful mesocarnivores of Polarica. Over 10 species are known, excluding the multitude of species that were able to reach the various islands of the continent.
Giant of the dwarfs
While diverse and widespread, all geotters are usually small-sized, rarely exceeding 20 kg (44 pounds)...none, except one.
The vulture marter (Osteolutra montana) is a massive geotter of over 50 kg, specialized in kleptoparasitism: its large size is a strong selection to scare away other geotters and carnivorous birds to steal their prey. The bigger you are, the scarier and tough you seem.
It's a direct descendant of the carrion marter and, unlike its ancestors, it's has a more compact body, showing a slow deviation from basal marters, that possess elongated bodies. Its jaws have become even more powerful, comparable to a spotted hyena. They are still solitarily predators, with large home ranges that can be as large as 300 km2.
While not being good hunters, vulture marters could potentially bring down weak ducktails and rostrids given the chance. They are mainly found in tundra and steppes, where carrion are more abundant and easily detectable.
Over the trees
Wotters (Arborilutrinae) are an arboreal radiation of geotters, that already appeared 10 million years ago. They are the most biodiverse group of geotters and the most abundant mammals (in terms of biomass) of austral forests. Their diet plasticity (they are the only truly omnivorous geotters) and their capacity to hunt both on trees and on the ground are the keys of success of these small mustelids.
The common wotter (Omnilutra costalis), as its name suggests, is the most common species, found across any forest ecoregion of Polarica. They are swift climbers with strong paws that help them to catch flying birds but also dig up in the bark of trees in search of larvae. Northernmost populations are the most frugivores, with fruit comprising up to 60% of their summer diet: due to this, they are one of the most important seed dispersals of forested habitats.
A more predatory species, the heavy wotter (Silvilutra arborea), is the largest species of its group and is capable of hunting and successfully bringing down ground rails and small anatids. Thanks to their short snout and giant masseters, a heavy wotter can fatally kill their prey with a single bite, proportionally as strong as the one of the vulture marter. They spend more time on the ground than common wotters, since their larger size and fierce behavior make them less appettible to other predators. In their habitats, heavy wotters are the main predators of the tree mossbrusher, a small semi-arboreal species of rostrid.
Walking on tiptoe
While wotters have managed to colonize the arboreal world, the descendants of the black biwolf have continued to perform their cursorial adaptations. Jackal biwolves (Cynolutra nominalis) are surely the most observable geotters of the Austral forest, with a total population of nearly half-million individuals. They are facultative omnivorous, eating sometimes fruits and seeds to assume supplementary vitamins and fibers. Despite resembling a small wolf, they are not social predators, being more similar to a fox. They mainly hunt young rostrids, ducktails and any species of ground tyrants, that can easily outrun in their environment. They are woodland specialists, rarely approaching semi-open landscapes, where they can easily fall prey to herdstalkers and giant raptorial birds: it's a hard life out there.
Only one species was able to live in open habitats, probably thanks to their swift structure and larger size: the steppe biwolf (Felicyon stepas). They are the largest species of biwolf, weighing nearly 30 kg. They are strong pursuers, capable of reaching 70 km/h (43 mph) for short distances. This mammal and headbutt rotbills are a typical example of parallel evolution: rotbills ancestors have evolved to be faster than their predators and vice versa, becoming the fastest land vertebrates on the continent. Steppe biwolves usually prey on young individuals, since adult rotbills are far too large to be killed. Despite its feline appearance, the steppe biwolf is anatomically more similar to a hyena or a wolf, incapable of using paws as an offensive weapon or to climb trees. They live in breeding pairs that cooperate during hunting: social skills are still not developed, definitely not as much as a shadowstalker.
The rarest of all biwolf species is the moon biwolf (Lutracyon nocturnus), a very elusive predator that can be found in the warmest areas of Belgrano (coinciding with the Queen Maud Land territory), where permanent soil frost lasts for only a few weeks in the year. They are mainly insectivores, using their robust body to dig in search of beetle larvae, giant crickets and wormflies. Their long snout is perfect to pick their prey inside holes, but it has indirectly reduced their overall bite force.
During Belgrano summers, warm temperature (locally 27°C (77°F) and moisture conditions favor the presence of snails, which become the main diet of the moon biwolf during this season. Despite being able to create their own home underground, it's not rare to see moon biwolves cohabiting with ground tyrants in the same den: the two animals do not interact, maintaining a commensalism association. Despite being labelled as a carnivore, moon biwolves ordinarily feed on plant matter for vitamine, especially fruits.
