Listed in order of recommendation:1. Learning Their Language: Intuitive Communication with Animals and Nature
I loved this book. It is a great "first book" with exercises about how to get started in learning how to communicate with other species. While Carol's is laid out very nicely, this book is first on my recommendation list because of it's easy style and exercises. 2. The Language of Animals: 7 Steps to Communicating with Animals
While I don't agree with Carol Gurney's insistence that there is no psychic element to speaking with animals (telepathy is telepathy, no matter how you use it), there is no doubt that "7 Steps to Communicating with Animals" is a straight-forward and clear cut introduction to animal communication.
She deliniates different aspects in different chapters, from behavioral problems to lost animals to death and dying. 3. Animal Talk: Interspecies Telepathic Communication
Penelope Smith is one of the forerunners of Animal Commuinications. Animal Talk is an easy read and it covers great introductory information. Whereas Marta and Carols' books are written from a more grounded perspective, Penelope explores the topic in a little more etherial way.