The Cloudrunner and the Rockwing

50 Million Years Post-Establishment

Where the continents of Striata and Wahlteria collided together around 40 million years ago now stands the tallest mountain range ever to exist on the world of birds, the hibernal mountains, a vast dividing range in the east-central region of the now-combined continent. Up in its high peaks dwells the cloudrunner, Spectralis nimbucursus (cloud-running ghost). This is a 40 lb raptorial viva of the banshee lineage, that makes its home in the coldest and stormiest summits of these mountains. One could live their entire life in the hibernals and never see a cloudrunner, an elusive predator that leaps from precipice to precipice with utmost agility, and appears at times to be unbound from the pull of gravity. It runs up vertical cliff walls, assisted by fluttering otherwise flightless wings, and when it must descend it simply leaps from the edge and delicately careens from one narrow foothold to another with its outstretched wings to slow its falls into graceful glides. As a banshee, its tail is uncommonly flexible, formed from only cartilage down the latter two-thirds of its length and thus the most "proper" tail any bird will evolve for many millions of years. It uses it as a rudder, turning on a dime, and spreads its tail feathers as a parachute in conjunction with its wings to control its leaping movements.

The cloudrunner is an ambush predator, hunting mainly the wary wallabeaks, fellow alpine avians that share no relation to it and have been pushed to the extreme heights from competition from other plant-eating vivas that now dominate the lowlands below. They leap instead of run, and deftly stand on nearly vertical walls to pick at the few tidbits of vegetation they find there. It must travel widely to find this prey, for to find enough scarce grass and leaves on these scree slopes to feed themselves they cannot stay in one spot for long. A cloudrunner has but one chance to catch the flighty wallabeaks when it finds them, and must time its attack precisely to catch them by surprise lest they escape quickly from its reach, and flutter across the chasms that it would take days to cross on foot. Lying on its belly and creeping forward in bursts only when its prey have their heads lowered, the cloudrunner disappears into a mottled background of stony crags and snow until it is directly on top of its target. Then it pounces swiftly downward, its full weight pinning the unsuspecting animal against the cliff. It digs in with a hooked talon on each foot and prevents escape in the moments before it can finish the kill with its extremely powerful bone-crushing beak. It is lucky to make one kill in two weeks, and will guard each one with its full attention to prevent scavengers like falconaries from taking its hard-earned prize.

Though solitary by nature, cloudrunners could not perpetuate their lineage without finding a partner at least occasionally, and when a female is ready to breed she will wail with a deafening shriek from the highest perches she can find for days on end, a call that lends them the name "banshee". It is a plea of urgency, sent out to the wind to hopefully catch the listening ear of a male who may be miles away and thousands of meters below her. The difficulty in hunting on these alpine cliffs makes it too dangerous for a female cloudrunner to hunt while incubating her single egg internally, lest she fall and break it within her, a potentially life-threatening situation. So begrudgingly, when a male responds to her call and makes the long trek to its source, he will stick around for some time after they mate. The male indeed takes full responsibility to provide food for his mate while she is denned up before the birth of her young, something rare among banshees. In exchange for his assistance, she will tolerate him if he shows up nearby again later, outside the breeding season, even though she is up to half again as large and could kill him if she wanted to ensure more food was available for her. Once the chick is born his role is done and he departs, leaving her to raise it. In this way, though females have only one young at a time, males may travel widely and help raise several over the short summer period before the mountains are again cast beneath a veil of bitter cold ice and snow.

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The wallabeaks are a lineage of leaping canaries whose ancestry goes back to among the earliest of Serina's birds. They share no common ancestors with any other living species for 49.5 million years, and are one of many canary groups which independently reached comparatively large sizes as "megafauna", though the living species do not qualify for this technically, and larger relatives are by now extinct. Wallabeaks are herbivores and particularly adapted to graze on grasses, but unlike vivas must swallow them in large chunks and break them down internally with the aid of stones held in the crop. Flightlessness occurred at least three times among its extinct members, some of which reached weights over 200 lbs, but the only species left today never surpass 65 lbs and all retain some ability of flight. Wallabeaks were widespread herbivores across eastern Serina in the Tempuscene, but faced growing resource and spatial competition from more efficient viva competitors, that later also became their main predators, too. Though wallabeaks were one of few large birds that retained the hopping locomotion of the original small canary as they grew, they did so mainly to quickly escape ambush predators, and their movement was not as energy efficient as leaping mammals like the kangaroo due to an inherent lack of mobility in their femurs which are angled horizontally forward, reducing their range of motion and the ability of their legs to store the elastic energy released with each impact, and release it again with each bound forward. Ultimately, wallabeaks across most of the continent died out in the face of faster running predators and herbivores with more effective chewing mechanisms that let them better feed on a grass diet. All modern forms are now alpine specialists with a range centered on the hibernal mountains where their long jumping abilities let them flutter from one cliff to another, reaching isolated patches of vegetation to eat and fleeing more grounded predators like the cloudrunner. In this last refuge where other vivas except for these few predators cannot reach, the strange and "primitive" wallabeaks can still succeed.

One remnant species of wallabeak that can still be found today is the unicorn rockwing (Rupesaltor unicornus - one-horned rock-jumper), a gangly bird which reaches a weight of 60 lbs and stands as tall as six feet. The rockwing is named for a long cartilage crest that rises from its skull, possibly used in social communication, but also a sort of "whisker" that lets it detect wind direction, and thus to angle its wings to maximize the distance it can fly. Its own power of flight is limited by its size - for it relies on its hind legs alone to launch into the air - and it is dependent on using those legs for a strong, leaping head-start and then on its wings to ride favorable wind currents to carry it the maximum distance. Unicorn rockwings are social birds and occur in groups of ten to fifty, depending on season and food availability, which let them keep an eye out for danger. Any suspicious sighting by one individual will result in a shrill, honking alarm call that spreads through the group until the whole flock is blaring their voices like a siren, and this itself is a deterrent to predators, especially inexperienced ones. Rockwings breed colonially in monogamous pairs that make their nests on small ledges out of reach of all but a few flying predators, but their chicks are highly precocial and leave their hatching grounds by two days of age. Their chicks, hatched in small broods of two to four, are equipped with fully developed flight feathers and are not only volant, but can fly longer distances than the heavier adults, letting them follow their parents around the mountain without the risk of falling. Adulthood is reached in the third year, at which time both sexes acquire a long trail of flowing tail feathers that mimics, at a glance, the bony tail of the vivas, but has little else in common.