Are there any of the successful stories about saving animals?

There are several; the Kakapo is a well-known success story. It was on the very brink of extinction when a radio series by Douglas Adams and Mark Carwardine called Last Chance to See featured the flightless parrot. This attracted publicity and funding to the project and, although far from safe (there are current 123 individuals in the world) that's better than the 50 that existed in 1995. It takes an extraordinary effort by dedicated people to do this kind of thing, but it is worth it.