I often wondered this myself during my undergrad years. A career in wildlife biology can be achieved with as little as a bachelor's degree to as much as a PhD. It really just depends on exactly what you are trying to do with your degree. Try to focus on a particular area of wildlife biology (marine conservation, land management, etc.) and go from there. Also, look up job postings in your field and pay attention to the positions that sound the most interesting to you. If those positions sound like something you can see yourself doing, then try to tailor your degree towards that area and get experience (internships, research projects with different labs at your school) to get closer to your goals. Hope that helps, and good luck in your pursuits!