The Sound Approach to Birding. A guide to understanding bird sound by Mark Constantine and The Sound Approach.
This book, if you haven't read it or even read it over a dozen times, will change your birding and the enjoyment you can achieve from it ten fold! For me, it was without doubt the most groundbreaking and interesting birding book I'd ever read, despite having a serious interest in bird vocalisations as it was; it answered so many questions for me and also open so many more doors to continue down to learn more.
Basically, a bloody great book and accompanying bird sound CDs, not to mention some terrific artwork to boot!
