The twin mountain ranges of Ailuropia can be seen as the continent's primary features. Both the internal basin and the coastal wetlands owe their existence to these ridges, and nearly all Ailuropian rivers begin high on their slopes. They were formed earlier in the planet's history, during a time when both the northern Perithalassic and Medithalassic seabeds were subducting under the continent. In bygone days, modest-sized ice caps covered the highest summits, while smaller peaks were home to less extreme tundras and taigas. Today, the glaciers flow into far lower elevations, subsuming the foothills and spreading out in every direction for hundreds of kilometers. In the northeastern corner of the continent, where the distance between the ranges is short, the two ice sheets nearly meet in the middle, threatening to cut off the lowlands from the Ailox land bridge. Already, many plants and animals that previously crossed freely from Ailuropia to Loxodia are finding themselves split into increasingly distinct subspecies, their gene pools split in half by the wasteland that separates them. On the other hand, for those that can make a living in these barren regions, the ongoing uptick in glaciation offers new opportunities.
On one chilly day in early autumn, a group of rattaloxen plods along, walking perpendicular to the slope of the hill where they currently graze. It has only been a few centuries since their species first crossed into this continent, but already herds numbering in the thousands can be seen wandering the steppes. They don't venture all the way to the highest peaks, for their mammalian lungs can't handle the thin air. Mountain kiwis (Petrapteryx), however, can climb to elevations that would be in the "death zone" for other animals, relying on their unidirectional respiratory systems to extract oxygen from the rarefied atmosphere. They don't spend their whole lives here, but right now their yearly migration has brought them to the glaciers for the all-important task of rearing their young.
After fattening up all summer long, pairs of mountain kiwis begin their climb as soon as they sense the days beginning to shorten. In good times, they graze and forage for bugs alongside the great kiwizelle and raspbird herds; though the mountain kiwis are less efficient at feeding, there is plenty of food to go around, so all can live in harmony as long as the growing season continues. Come winter, though, they cannot compete with the other birds, so they gradually make their way up the mountains. Here, conditions are harsh but food is relatively abundant, especially in the form of underground spiny-grass rhizomes and caches of rat-grass seeds. To successfully hatch their chicks, though, Petrapteryx couples must climb even higher, building their nests on bare ice covered with a layer of down plucked from their own bodies. Once the egg is laid, the male and female take turns incubating; it would only take about fifteen seconds of exposure to kill the developing embryo, so great care is taken to ensure it never goes unattended. When spring arrives, the trio will descend once more, feeding on abundant woodlouse-grasses, insects, isopods, and even small birds and rats. The chick usually remains with its parents throughout its first year, following them back up the mountain before wandering off to find its own mate (though most do not succeed until their second or third year).
Invertebrate communities in this environment are sparse; a lack of standing water means there are no mosquitoes except those capable of flying long distances. Many flagelloculicids have this ability, especially wranglers, whose powerful flight muscles that originally allowed them to carry large prey now permit them to soar for many kilometers without rest. Similarly, dustflies, attracted by large populations of newly-evolved montane sweetstalks, arrive in flocks of millions from the surrounding plains a few times a year. Many woodlice are common as well, like the descendants of sweetstalk-loving Palustrarthus, which followed their host plants as they adapted for life in this habitat. Castlebugs and squashroaches also have a presence wherever the ground does not entirely freeze, while hardy dermestimimids even venture onto the glaciers proper to scavenge for unlucky kiwi eggs before they completely harden into ice.