The beginning birder as well as the expert can benefit from this set of three cassettes or CDs. Presented in 17 learning groups, you'll learn birds with similar calls as well as habitats. Putting the educational focus on subtle differences helps create an even more sophisticated ear, as you will learn to distinguish similar calls within any given habitat. Geographically focused east of the Rocky Mountains, this expansive set contains calls of over 80 species. Drawn illustrations also aid in visual identification. There is also a self-quiz feature to help you learn. You'll become a better birder when you employ this set methodology as well as actually getting into the field."