Master
builders

The great construction abilities are what distinguish Aves ex Machina (AeM) society from any other animal. It is however interesting to note that their dormitories are extremely simple and comparable to those of other birds, while the same cannot be said for their intensive breeding facilities. These "barns" are probably the largest animal-made architectural structures ever observed in Antarctica (excluding human constructions) and can vary in shape and size depending on the species being bred. They are called "arenas" due to their relatively circular structure with an apical opening, and they are built using countless materials.
The main arenas' constituent is usually clay, which, when wetted and dried, allows for shaping. The product is often mixed with grass, rocks, and wood to strengthen the structure, which must endure the strong rainfalls and winds found in the subtropical regions of Antarctica.
Arenas can be built in various locations, even on rocky slopes, but they are more common and larger in flat areas rich in wood. Fallen branches are often used as a structural base for the arenas, both for stabilization purposes and for creating perches. While young arenas tend to be relatively small (a pair of meters wide), the continuous supply of clay and other materials over time transfrom them in gigantic buildings that can reach 10 meters in height (32 ft).

The construction of arenas is almost exclusively carried out by solicrafters, who, with their large pelican-like beaks, can transport large amounts of building material. Battle cargos may sometimes participate in material retrieval, while scouting sentinels (and rarely, storing executioners and all nannies) often collaborate in constructing the inner chambers . Among the various identified arena forms, two construction trends can be observed: arenas for mammals and arenas for reptiles. For mammals, the greatest risk is livestock escape or predation by other predators, so the arenas take on a cylindrical and tall shape. For reptile arenas, the main challenge is to maintain sunny sites for basking, shaping the arena accordingly into a donut-like form (wider and less tall).
Arenas protect the livestock not only from predators, but also from thermal extremes: the clay works as a thermal insulator, although inefficiently, because of the large holes for air recirculation. The maintenance of these infrastructures is a strong limiting factor to the distribution of Aves ex Machina: the large abundance of clay and other materials for construction can only be found near large river basins and other wetlands (both marine and internal).
Large herbivores and some burrowing predators also seems to be a strong limiting factor: while extremely robust, arenas can't do nothing against a large vertebrate trampling the forest canopy. Both herbivores and predators are often attracted by arenas, respectively for the fresh vegetables reservoir and the livestock itself.