Crested Cascader

The crested cascader is a mid-sized serilope living in the taiga region of North Anciska in the early Thermocene, 100 million years post-establishment. These social herbivores, which weigh about 150 lbs, feed mainly on coarse needle-like evergreen plants, though in summer they readily take the more nutritious buds and leaves of deciduous sunflower trees, and in harsh winters will gnaw on carrion - even of their own species. They are named for the effect given by the long plumed headcrests of both sexes which ripple as the animals travel in close herding formation, resembling the flow of a cascading river over rocks and rapids. Male crested cascaders are a rusty red to orange color, with darker heads sometimes showing a blue sheen, while females are a soft fawn color and about 25% smaller. Both sexes share white legs and cheeks and throats, though only males have a feathered beard beneath their chin, and only males sport paired horns on their snouts; they use these to spar against each other during the late winter breeding season in contests to secure mates. Unlike most horned serilopes, like the related but much larger ornitheres, cascaders' horns are sheathed with keratin like a talon, and they shed most of their horns after the breeding season ends. They retain only a small slightly forked nub about two inches in length - this is the only component made of bone. A new, slightly larger pair of branched structures regrow over the horn base in the following spring.

In winter cascaders travel in large, nomadic groups of mixed sexes for safety, separating into smaller flocks when spring brings more food and cover to the landscape. Then, single males which have secured a dominant position in the hierarchy through late winter sparring are permitted to join female herds numbering five to fifteen, all of which he will couple with. These small herds are composed mainly of relatives, and are long-lasting social structures that group with each other in winter, but don't really mix even then. Familiar individuals remain by those they know, and even when feeding each related flock may keep a few feet of distance from its neighboring flock. Protection of the young from danger is communal, and the young are born all within a few days of each other and herded together in a creche, though females usually do not feed any chicks but their own.

New males typically join each year as rivals are always ready to take on the last year's winner, ensuring genetic diversity in the herd over multiple seasons; sons born in the group are driven out at the age of 20-22 months, just before sexual maturity. Males often fight frequently through the end of winter and into the first weeks of spring, and sometimes multiple males will each spend just a few days with the herd until they are dethroned by another contender, meaning not every female's young may have the same father, which can be a benefit for overall fitness. Yet it is very rare for a rival male to displace a breeding male once any offspring are born, because after this time the females will aggressively mob any unfamilliar male as a collective, protecting their chicks from potential infanticide. Once young are older, by next winter, they will no longer do so, and the male will then have to fight his own battle if he wants to try and stay with them for a second summer.

Females leave their birth groups only rarely, though some may do so during the winter migration to more southerly feeding grounds. Yearling females, having never made the trek before, sometimes get separated from their families and follow different herds, either joining with them for the summer or otherwise finding company in other disoriented youngsters to begin completely new groups. Occasionally very large flocks may also break into two smaller units during the spring, usually driven by a younger adult challenging an old matriarch for leadership and ultimately splintering the group as some choose to follow the old leader, others the new one.