I don't know about technical terms used in zoology or other sciences, but 'gregarious' sounds quite strange to me here. In a nonspecialist sense, at least, it means outgoing, extraverted, enjoying conversation and social interaction. That would be primarily humans by definition, at most perhaps chimpanzees or possibly dolphins, whales, other animals that seem to communicate more with each other on a level beyond just signaling things in the environment like food, water, danger.
As I understand it, herd animals group together not primarily because they need social stimulation in the sense of higher-level communication, but simply because there's safety in numbers. A lone animal is more likely to become prey, and more eyes and ears mean a better warning system against sudden dangers.
I personally would repeat the word 'animal': as a herd animal, flight animal, and prey animal.
And really, isn't there some overlap here? Aren't, for instance, all flight animals also prey animals? Flight is just another method of resisting predators, along with, say, camouflage, kicking, biting, poison ... So it seems to me that flight animals ought to be a subset of prey animals, which makes it look odd to list them together in one group as if the categories were equal or parallel.