Odds of Hanging On
Typically, wildlife rescuers start as volunteers before they become salaried rescuers for a shelter or reserve. If you want to make that transition, you'll have to prove you're competent, you know how to care for animals and their facilities, and that you can stay safe and keep the animals healthy.
Remember: You're not there to make friends with animals; you're there to save their lives. People who treat the wildlife as pets instead of wild creatures in their care will find they don't last long in the field. There's too much heartache.
After a few years of experience, your career can go in different directions. Some people choose to become independent wildlife rescuers while others work with shelters or reserves. Make sure to beef up your people skills along with your animal savin' skills. If you can do this, you should have no trouble sticking with it—after all, it's not like there won't always be animals in need of rescue.