Qualifications
At the bare minimum, you're going to need a bachelor's degree in zoology, wildlife biology, or something similar like ecology. A BS is fine for an entry-level position, but if you ever want to move up in the ranks of zoology, you absolutely have to get an MS. This is where you'll most likely zero in on your field of study. Master's in ornithology? Yeah, they're out there—along with every other zoological focus you can think of.
If you want to reach the top of the top and apply for your own research trips, get tenure at a university, or head-up a team at a lab, you'll have to get your PhD. It'll be a lot of work, but it'll be worth it when people call you doctor.