What should I study if I want to be an wildlife biologist?

I really look up to people like steve irwin and jeff corwin and been thinking about doing what they doing wildlife biology for college. I don't know what cles I should take though. Basicially, I want to do what they do. They always seemed so happy. Now, I really like animals ever sense I was a kid. When I got a little older I realize I wanted a pet. I got one took care of it really well. Even the shop said my iguana was really health and beautiful. So I know I really like reptiles alot, ok. As I got older, I learned I was doing wrong by keeping my pet in a cage even though I did let him out and crawl around and go outside. I realized I was wrong for buying a pet and keeping him in a cage even though he was well cared for. After a few yrs he die on me. And sinse then I havent got a pet. Cuz, I learned it was wrong to keep a pet even if you take care of it. He, wasn't allow to live in the wild like others. So, I'd figure I be a wildlife bioligist. but, am not sure what cles to take or anything. So if anyone could help me that is one or know info on what I should do? So, I can be a wildlife biogist like the great Steve-O!