Quartzkarst, Part 3: Avalanche

It has been 400,000 years since the start of the Ice Age. Glaciers are nearing their maximum extent, covering entire continents in kilometers of ice. Temperatures have ceased falling because dinoflagellate algae are growing much more slowly without abundant atmospheric carbon. However, the glaciers are still growing, and they will continue to do so until their terminal edges reach climates warm enough to melt them as quickly as they grow from their montane origins. All of the Northern Isles, Unciolis, and the northern half of Ailuropia and Loxodia have been lost, along with significant portions of lower-latitude areas. The Ailurentide ice sheets have converged in the east and west, fully enclosing a small area of fertile taiga and tundra in the middle. This ring of ice became complete only a few decades ago when the two unstoppable forces plowed into one another in the southwest. In the years prior, woodlouse-grassland flora and fauna escaped by migrating out the narrow gap, establishing themselves along the coast where the local loop-grass had recently gone extinct. For now, the loop-grassland still exists in Abeli and Loxodia, kept alive by its larger size, though even it is declining, having been fragmented by the encroaching Gillywog ice sheet.

Back in Ailuropia, ice continues to flow outward in all directions from the mountains. So strong is its current that it picks up massive boulders with ease. These can be carried many kilometers from their starting point, often getting deposited at the edge of the glacier when the ice around them melts away. Occasionally, though, the ice meets an object so immovable that it has no choice but to move around it. Such is the case for Tepui Mons, a massive quartzite formation that juts out of the surrounding land, too huge and sturdy to be washed away by movements of the ice. Instead, as the two ice sheets converged around it, they turned it into an island, a lone patch of livable land surrounded by frozen desert. 

Not all of Tepui Mons's inhabitants have survived their new reality. The tepuine pillbird went extinct during the Late Muricene following the loss of the skyplague, their preferred prey, to disease. The Great Decarbonisation also killed off the longclawed ratweasel, which found itself unable to breathe the anoxic mountain air. Many local mosquitoes perished as well, as most sources of stagnant water are now frozen. One species of dusfly survives, feeding on the cold-hardy sweetstalks that make up over a third of the Tepui's low-growing plants. Large pseudotrees are gone, as cold temperatures prevent anything taller than a meter from growing, but there is a population of diminutive hybrid trees that made their way onto the plateau about 150,000 years ago.

Mountain kiwis are still common, though the loss of their arboreal habitat has forced them to take on a more generalistic niche. They are the smallest of their genus, weighing no more than three kilograms, and feed on a combination of tough plant matter and carrion. Their species lives in the shadows of the much larger Acrapteryx tomentosus, a herd-bird whose ancestors were some of the first to reach the Tepui all the way back in the Early Muricene. They are the legacy of the once-dominant Apteryx grandis, a species that went extinct elsewhere due to the rise of kiwizelles two million years ago. While poor climbers initially, they have had hundreds of thousands of generations to adapt to their new life here, and they are now unmatched in their precision and dexterity. With an elongated tail that acts as a counterbalance, they keep themselves steady as they climb across rocks and leap over gulleys. They remain primarily grazers, spending most of their waking hours feeding on sweetstalks and other small grasses in hard-to-reach locations. However, like many animals, they've become less specialized to survive in the low-productivity world of the Ice Age. About 500 of them live in a single herd that patrols the mountain, never staying in one place long. 

These mountain herd-birds are some of the longest-lived kiwis, living more than half a century if they don't die during childhood. Many are still alive that saw the ice first surround their home, though they certainly thought nothing of it at the time, for that event changed little about their day-to-day lives. For several decades now, they've gone about their business unaware of what's been happening beneath their feet. Over the past few months in particular, tremors have shaken the Tepui regularly, though the sure-footed birds were largely unaffected by these quakes. This morning, though, the herd was awakened quite suddenly to the ground falling out from below them. 

Thousands of tons of stone and debris begin to tumble, falling hundreds of meters onto the ice below. The entire western face of Tepui Mons sloughs off, slipping into a horizontal position atop the glacier as more material continues to rain down from above. As the landslide continues, the pile of fallen rocks grows and spreads further. By midday it settles into a stable slope, resting at about a thirty-degree angle. Buried beneath this ramp are a few unlucky members of the herd, which by chance had been sleeping nearby when the avalanche began. The survivors survey the rubble, hopping carefully from one rock to another. Driven by fear to get as far as possible from the site of the disaster, they flee their home and make for the glacier below. Finally, after a descent lasting many hours, their feet touch ice as the sun begins to set. They push on, their empty bellies preventing them from sleeping even after night falls. As the temperature drops, though, younger members start to cry out, shivering and hopping from one foot to the other to prevent frostbite. Their parents finally acquiesce, tucking the chicks into their dense plumage as the herd makes camp for the night.

In the morning, pangs of hunger drive them to rise earlier than usual. Many individuals attempt to turn around and return to the Tepui. Before long, though, they feel the earth shaking once again. Their old home isn't safe anymore, and it likely won't be long before more of the mountain collapses. In the other direction, they can see where the glacier ends, terminating in a wall of ice overlooking the prairie only a few kilometers away. Streams of water pour out onto a landscape that stretches far beyond the limits of their vision. The ice grows slick when they approach the edge, but their sharp claws keep them anchored as long as they stick to flat ground. They are soon standing directly above the woodlouse-grassland, looking down a sheer drop of about twenty meters. A few brave birds try climbing down the ice, but they find themselves unable to grip the cliff face. They turn back, rejoining their herd; could they really be stuck after coming this far?

A week-old bird wanders off from its parents in the confusion, staring down at the grassland with wide, confused eyes. It walks near the edge of the ice, finding a stream channel that appears to drop straight into the glacier. By this time, its disappearance has been noticed, and the adults begin sounding alarms. Realizing how far it has strayed, the chick tries to run back to its mother, but it trips and falls into the crevasse. The herd rushes to its aid but arrives far too late; it has already disappeared out of sight. Knowing they can do nothing for the lost hatchling, the others disperse quickly, leaving only its parents to mourn their loss. Though normally a highly social species that forms lifelong bonds, the other Acrapteryx are simply too exhausted to care. Most of them simply pace restlessly at the edge of the ice, frustrated at their inability to reach the abundant food just a few dozen meters away. Gazing at the foot of the glacier, one spots movement in the tall grass. Then it hears an unmistakable call: three short, high-pitched chirps in a row, followed by a pause, then a loud trill - the distinctive cry of a baby A. tomentosus trying to find its parents.

A crowd forms, vocalizing back and forth with the stranded chick. Its mother pushes its way to the edge and recognizes its offspring immediately, then runs back to the crevasse. Its herd, not realizing what it intends to do, squawk angrily at it for causing such a disturbance. It ignores them, plunging headfirst into the small tunnel and emerging out the other side a moment later, reuniting with the hatchling. Her mate soon follows, as does the rest of the herd once they understand what is going on. One by one they arrive, congregating in the shade against the wall of ice. When all had safely descended, they turn their attention to the endless plains that surround them.

Compared to earlier ages, the woodlouse-grassland is at an all-time low in terms of size and diversity. However, to a species that evolved to live in a single, restrictive habitat, it appears as a land of plenty. Despite the immense scale of their new world, the birds have a strong instinct to live as a tight-knit herd. As the first few days and weeks turn to years and generations, this unified population swells into the tens of thousands, wandering the woodlouse-grassland from the shoreline all the way to the foothills. Predators find them uniquely difficult to catch because their long, mobile tails grant them increased agility, allowing them to easily outmaneuver even the fastest terror kiwis. In less than a century after leaving Tepui Mons, this species rises to dominance as the most abundant grazer in its relict woodlouse-grassland ecosystem.