The first rule in wildlife photography safari tours is "be patient". Wild animals will do what wild animals do in their own time. If you are looking for a specific wildlife photograph don't expect the wildlife and weather to cooperate all the time. Sometimes animals and birds just aren't where you expect them to be.
This leads us to the second rule, which is "be flexible". You may have gone looking for one subject, but if you don't see it, you'll probably see some other wildlife that might pleasantly surprise you.