Several years ago I visited the nature center in Poynette on a bus trip with the director of the local nature center and about a half dozen other volunteers there. The Poynette center had a program of rehabilitating birds and wild animals. At the time of our visit, we were especially interested in the two raptors they had undergoing therapy. One was a large barred owl, and the other was a kestrel. The owl seemed further along the road to recovery, and could flap its wings strongly. The little kestrel was looking a little lopsided.
The birds had outdoor cages, and the one for the owl was especially roomy -- I would say big enough for an eagle or large hawk. But they were also taken on the rehabber's gloved hand for walks or presented to visiting groups for an informational chat. The owl (or other bird) was perched on a handy branch and encouraged to exercise its wings.
At the time, the local nature center had a little screech owl, named Otus, which was used in educational talks to local school groups. He had suffered a dislocated shoulder which never healed properly. So he had his own indoor cage and a steady supply of mice, nicely thawed out in the office microwave. In fair weather he was taken outside as often as possible for air and sunshine.