A field guide is a book with interesting background information on various aspects of the wild. It's a good idea to buy a field guide which is directed specifically to the area that you will be visiting, e.g. "Mammals of the Kruger Park" or "Birds of the Kruger Park". A good field guide will include a picture and/or drawings of each animal, it will describe mating rituals, when and how many young are born each year, what food an animal eats, where in the wilderness you will find a particular animal, natural enemies, how old they get, what the social structure of a particular species is and how it functions, etc. Field guides covering various topics are available including trees, flowers, birds, mammals, predators and birds (comprehensive or specific such as raptors or lbj's).