As far as careers go in the overall field of Wildlife studies, I suggest you discuss the matter with local wildlife managers, and see what they recommend. My advice is to study a broad range of topics related to plants and animals and see which area sparks the greatest interest. Even if you’re sure you want to study animals, make sure you take some classes in botany and plant taxonomy, knowing plants and plant communities is essential to studying most animals in the field. Also get a good handle on statistics, being able to design experiments and interpret field data will hinge on your ability to relate to statistical methodology.
One other thing, wherever you go to school, take advantage of the faculty available, find out which professors are tops in their field and check out their classes, I attended a University with a superior entomology professor and although I wasn’t particularly interested in insects, I took a class from him, and ended up pursuing a degree in entomology. A great teacher who teaches from the heart will inspire you and make your college career more rewarding. Good luck.