Hippity Potamus and Blackety Bird

The book is about a symbiotic relationship between a hippopotamus and a bird. The bird rides on the hippo's back, eating the bugs that bug the hippo, and the hippo provides protection for the bird. They become great friends but, as friendships often proceed, they argue, separate and go their separate ways. Suddenly, realizing how much they miss each other, they reconcile and reunite, and agree that they will argue no more. It is a happily ever after book.