In winter, bison moved to southern ranges of variable weather and more snow, which kept low-growing grass leaves moist and fresher than in the dry northern plains. They were skilled at sweeping snow aside with their noses and cheeks to find their preferred close-to-the-ground feed, but the snowy steppes of the south were not without risk.
Though it kept them warm in the relatively dry cold, even of the south where more snow fell, the heavy, shaggy coats of bison and other warmly dressed animals that migrated south in winter could be hazardous or even fatal when the climate turned cold and wet, with frequent shifts between freezing and thawing. If their coats became soaking wet during a thaw, they could be vulnerable to a fatal chill during a subsequent freeze, especially if a cold snap caught them resting on the ground. Then, if their long hair froze fast, they would be unable to get up. Excessively deep snow, or icy crusts on top of snow, could also be fatal, as well as winter blizzards, or falling through the thin ice of oxbow lakes, or flooding river valleys.
Mouflon and saiga antelopes also thrived by selectively foraging on plants adapted to very dry conditions, small herbs and ground-hugging leafy shortgrass, but unlike bison, saiga did poorly on broken terrain or in deep snow, and they were not able to leap well. They were fast long-distance runners that could outdistance their predators only on the firm level surfaces of the windy steppes. Mouflon, the wild sheep, on the other hand, were expert climbers and used steep terrain to escape, but they could not dig through snow that piled up. They preferred the windblown rocky high ground.
The goatlike species related to mouflon, chamois and ibex, divided their range by altitude, or by differences of terrain and landscape, with the wild goat-antelope, ibex, taking the highest ground with the steepest crags, followed at slightly lower elevations by the smaller and very nimble chamois, with the mouflon below them. But they were all found in rough terrain of even the lowest levels of the arid steppes, since they were adapted to cold, so long as it was dry.
Musk-oxen were also goatlike animals, although larger, and their heavy double coats, which resembled the fur of mammoths and woolly rhinoceroses, made them seem bigger and more "oxlike." They nibbled continuously on the low shrubs and sedges, and they were particularly adapted to the coldest regions, preferring the extremely cold, windy, open plains close to the glacier. Though their underwool was shed in summer, musk-oxen became stressed if the weather turned too warm.
Giant deer and reindeer kept to open ground in herds, but most other deer were browsers of tree leaves. The solitary woodland moose were rare. They loved the summer leaves of deciduous trees, and the succulent pondweeds and water plants of marshes and lakes, and with broad hooves and long legs, they could negotiate marshy, boggy bottomlands. In winter they survived on the more indigestible grass, or high willow twigs of trees that grew on the low ground of river valleys, their splay-footed long legs easily carrying them through the windblown snow that drifted and piled up there.
Reindeer were winter-loving animals, feeding on lichens that grew on barren soil and rocks. They could smell the favored plants, even through snow, from a long distance, and their hooves were adapted to digging down through deep snows if they needed to. In summer they ate both grass and leafy shrubs.
Elk and reindeer both preferred alpine meadows or herbaceous highlands during spring and summer, but below the elevation of the ranging sheep, and the elk tended to eat grasses more than shrubs. Asses and onagers invariably preferred the arid higher hills, while bison ranged a bit lower, though they generally climbed higher than horses, which had a broader choice of terrain than mammoths or rhinoceroses.
Those primal plains with their complex and diverse grasslands sustained in great multitudes a fantastic mixture of animals. No single place on a later earth did more than approximate parts of it. The dry, cold environment of high mountains could not compare, though there were similarities. Mountain-dwelling sheep, goats, and antelopes extended their range to the lower ground then, but large herds of plains animals could not exist in the steep, rocky terrain of high mountains when the climate of the lowlands changed.
The soggy and fragile northern bogs were not the same. They were too wet for much grass to grow, and their stinting, acid soils caused plants to develop toxins to avoid being grazed by the great multitudes, which would destroy such delicate slow-growing flora. The varieties were limited and offered poor nutrients for the diversity of large herding animals; there was not sufficient feed. And only those with wide splaying hooves, like reindeer, could live there. Huge creatures of great weight with large stumpy legs, or fast runners with narrow dainty hooves became mired in the soft, wet land. They needed firm, dry, solid ground.
Later, the grassy plains of warmer, more temperate regions developed distinct bands of more limited vegetation controlled by temperature and climate. They offered too little diversity in summer, and too much snow in winter. Snow also bogged down animals that required firm ground, and it was difficult for many to push aside to reach food. Deer could live in woods where the snow was deep, but only because they browsed leaves and twig tips from trees that grew above the snow; reindeer could dig through snow to reach the lichen on which they fed in winter. Bison and aurochs subsisted, but they were reduced in size, no longer reaching their full potential. Other animals, such as horses, decreased in number as their preferred environment shrunk.
It was the unique combination of all the many elements of the Ice Age steppes that fostered the magnificent multitudes, and each was essential, including the bitter cold, the withering winds, and the ice itself. And when the vast glaciers shrank back to polar regions and disappeared from the lower latitudes, so, too, did the great herds and gigantic animals become dwarfed or disappear entirely from a land that had changed, a land that could no longer sustain them.
While they traveled, the missing parfleche and long poles preyed on Ayla's mind. They were more than useful, they might be necessary during the long trip ahead. She wanted to replace them, but it would take more than an overnight stop, and she knew Jondalar was anxious to keep moving.
Jondalar, however, was not happy about the wet tent, nor the thought of depending on it for shelter. Besides, it wasn't good for wet skins to be folded up and packed together so tight; it could make them rot. They needed to be spread out to dry, and the hides would probably need to be worked as they were drying to keep them pliable, in spite of the smoking they had received when the leather was made. That would take more than a day, he was sure.
In the afternoon they approached the deep trench of another large river, which separated the plain from the mountains. From their vantage point on the plateau of the open steppes, above the broad valley with its wide, swiftly flowing waterway, they could see the terrain on the other side. The foothills across the river were fractured with many dry ravines and gullies, the ravages of flooding, as well as many more running tributaries. It was a major river, channeling a good proportion of the runoff, which drained the eastern face of the mountains into the inland sea.
As they rounded the shoulder of the steppe plateau and rode down the slope, Ayla was reminded of the territory around the Lion Camp, though the more broken landscape across the river was different. But on this side she saw the same kind of deep-cut gullies carved out of the loess soil by rain and melting snow, and high grass drying into standing hay. On the floodplain below, isolated larch and pine trees were scattered among leafy shrubs, and stands of cattails, tall phragmite reeds, and bulrushes marked the river's edge.