Every bird of prey show I have seen was put on by rehabbers using birds that had been injured in the wild and healed but were unable to fly and hunt again. their handlers treated them with great care, and they served as ambassadors from the wild. Children especially are SO impressed at being up close to an owl or hawk, and learning about how they live, it is a valuable lesson in conservation.
Marine mammal shows are another thing entirely. I've seen a few, and the only one that didn't totally turn my stomach was at the Indianapolis zoo, where they had a really huge facility with three large interconnected pools containing about 5 harbor dolphins, fairly small animals with lots of room to race around in. The trainers were using positive methods and the dolphins seemed healthy and active. I've heard that intelligent animals enjoy having a "job" that they do well and are rewarded for, but I'll bet they would rather have a short and stressful life in the open ocean.
