A followup to this sequence The human frame, evolved for striding across grasslands on earth was not designed for flight. It could not work up enough thrust to get off the ground without extensive mechanical aide. A fact which soon made itself known to the Avians created (either made from scratch by modification of existing humans) in the 21st century. While modified feet could serve as hand their wings were poorly suited for flight their wings were of little use even with hollow bones. This often left these beings at something of a disadvantage. While felinoids and caninoids could integrate into human civilization easily, the Avians often found themselves as outsiders. As such it was little surprise that in 2152 to 2175 the bulk of their population left earth on a fleet of eight colony ships, making the long voyage at relativistic speed for a distant gas giant. After more than three centuries in stasis they awoke and set to work on building a new world on a moon. Most colonists at this time sought out earthlike worlds or worlds that could be comparatively easily terraformed. The Avians sought a moon slightly larger than Luna to make their new home. Airless, but with only a fifth earth's gravity.At first they established domed cities, but as time went on they erected a much grander project and encompassed the entirety of their world and over the next few centuries enclosed their entire moon beneath a canopy a kilometer above the surface of the planet to maintain a pressurized environment. The regolith was turned to soil in which grew massive 400 meter tall genetically engineered trees. In this environment they could take wing and freely fly. When the first hyperdrives were developed in the 28th century, the Avian World soon emerged as a major hub for interstellar tourism. While species transition had fallen out of favor by that time, a fair number of migrants had 'gone native'.