What woud you consider a wild animal

I'm doing a college project on wildlife native and invasive living in zoos and I'm try to figure out what counts as wild since there are free range peacocks at the zoo who can leave but don't are they wild. And thers a lake with ducks and the have 4 gadwall ducks there and 5 showed up and the 4 there where allredy there could fly so are they wild? There are also pond sliders that aren't owned by the zoo but where brought in but the public and just relased there so dp those count ad wild? Thoughts woud me great thanks

Thanks for the responses but I don't think I made it clear what meant. I ment shoud I consider those species in my study for example if I see a blue tit I'll note it down since it a wild bird that flew in but if I see a gadwall duck do I note becues the zoo brought some in for display but they can fly away if they want that is where I'm confused.