Lore about those:
They run very fast and catch flying bugs in their wide open beak. Its lower part is full of small holes that let air through, but not bugs. Those holes -small rips in the skin below the beck- grow little by little, which means a young ostrican will find it way harder to run with its beak open, because of air resistence - but it is still partly fed by its parents at this point. An old ostrican on the contrary has holes too big that let too many insects pass, and has to hunt longer before it’s full. They drink with their head upside down, siphooning water between the tongue and the upper beck. Young ones have a thin down, not really warmth-efficient; so till their feathers grow, they sleep under the wings of their parents - or, during the day, under one of the adult animals’ chosen by the group as the chicks’ keeper -it tends to change every day, unless one is unable to hunt, in which case it has to keep the chicks. The older ones, often chosen for chicks-keeping, have longer feathers, that provide better thermal isolation and let them go on short flights - glorified jumps, essentially.
They have a short but dense fluff that is both warm and impervious to rain, and their elytra are optimal cover for their back. When feeling threatened, they flatten on the ground, and thanks to the shape of their beak drill their head into the soil from which they are very hard to dislodge. Only the armored parts of their body, those covered by the elytra, are then visible. their vertebrae and the very loose skin of their neck let them turn their head by several times 360°. When it gets cold, they stick their head in their shoulders, and this loose skin forms bulges which are good thermal isolation.
They live in vast windy prairies, in groups of a dozen individuals, several groups maintaining a shared surveillance mesh against predators, never grouping too close or falling too far apart. Though small and sturdy to resist the cold, the boarses are very fast, thanks to their leathery "sails" catching the ever-present wind. They eat grass and moss. Their very wide hooves help them keep their balance on the pebbly ground. When the wind falls (or goes the wrong way I guess? but like with sailing, you can catch the same wind to go different ways), they're very vulnerable.
The "sails" are attached to the top of the shoulders, resting on the back when closed, and standing upright when used. Some ethologists say they're all different and help the boarses differenciate between individuals, but nobody really got convincing evidence, especially since they seem to change patterns depending on the light; some others think they release an odor, when a boarse flees at full speed, that warns others of the danger; some more think it's not an olfactive but a very low-pitched sound signal.
They have strong lips and teeth, and wool-like fur, mane and tail.