Experienced birders tend to do things that make them look like wizards to beginners. One of the things that often both impresses and confounds the neophyte is an expert’s ability to catch a glance of a back-lit bird flying out of a tree or a shorebird standing by a pond a half-mile away and nail the identification seemingly without thought. For better or worse, there’s no magic involved. What the experienced birder is doing is birding by impression (BBI).

There’s nothing new about birding by impression. It’s been used by birders forever, and recent guides have focused on the BBI method for identification of shorebirds and raptors. Now there’s a book that addresses BBI techniques in general and its application to all of the bird families of North America.

It’s both ironic and fitting that the Peterson Reference Guide to Birding by Impression carries the Peterson name. Roger Tory Peterson, the father of field guides, created the “Peterson System” that focuses on field marks, usually details of plumage that distinguish one bird from another. For decades, field guides by numerous authors used the Peterson System, and some of the best still do today. In Birding by Impression, authors Kevin Karlson and Dale Rosselet approach identification through evaluation of size, shape, structure, and behavior, without an emphasis on plumage. Despite this being a dramatic departure from the Peterson System, Pete Dunne asserts in this new book’s forward that the late Peterson would have been thrilled with this new treatment as he himself was a practitioner of BBI.

BBI involves a lot of what seasoned birders have long referred to as GISS (usually pronounced jizz). GISS is an acronym for “General Impression, Size, and Shape.” Add an assessment of behavior to traditional GISS and you have BBI. There’s a small bird with a thin bill perched above a pond, making short flights and constantly bobbing its tail. It’s probably an Eastern Phoebe. You don’t need color to identify that bird, you just did it by BBI.

Pete Dunne’s Essential Field Guide Companion textually addresses points of GISS identification for most of North America’s birds. Since then, The Shorebird Guide launched a new trend in identification guides of using size, shape, and structure as critical components of ID. Kevin Karlson, a co-author on The Shorebird Guide, has now teamed up with Dale Rosselet for Birding by Impression, which is far more of a reference guide than an identification guide. You won’t find every bird in North America mentioned in detail in this book, but you will find every family addressed with emphasis on challenging differentiations within each.

Photos are a key part of Birding by Impression. You’ll find plenty of photo quizzes to test your BBI skills, and the book is filled with both detailed images of birds and realistic field photos of groups of different birds. The latter has become a staple of modern identification guides since The Shorebird Guide. Since you often see groups of terns together in the field, why not show Caspian Terns and Royal Terns in the same photo?

Every group section begins with an introduction followed by the BBI information: size, structural features, behavior, general coloration, habitat use, and vocalizations. Following this is a comparison of similar species within the group or family. For these challenges, both unchanging features and non-BBI details are covered.

Just as the best identification system combines a variety of techniques, the best arsenal of identification guides for a birder includes a range of books. Birding by Impression can be an important part of a collection that also includes traditional field-mark guides, GISS descriptions, and specific family, group, and regional guides. Birding by Impression is best read before turned to in the midst of an identification crisis. Consider it training in the art of BBI.

Most of the specifics of identification challenges have already been covered in other books. Shorebirds were fully treated in The Shorebird Guide, terns and others in the Field Guide to Advanced Birding by Kenn Kaufman, and raptors in Hawks in Flight by Sibley, Dunne, and Sutton, and several subsequent books by Jerry Liguori and Richard Crossley. Experienced birders with those tomes already in tow may not find a need for Birding by Impression. For the beginner with only a traditional Peterson-style guide in hand, this is a wonderful introduction to BBI themes for all of the bird families.