Peterson Reference Guide To Birding By ImpressionPeterson Reference Guide to Birding By Impression, A Different Approach to Knowing and Identifying Birds With more than 200 photos this comprehensive reference guide portrays birds in their natural habitats. Birders are challenged to view their subject matter in a manner to accurately define the subtle differences in plumage, structure and calls of similar birds. Physical features, behavior, plumage, habitat, and vocalizations are clearly stated.