Practically a textbook, Smithsonian Birds of North America offers full descriptions of all 922 species of bird documented on the continent.

Alsop abandoned the field guide approach and instead strove for completeness, creating a hardcover book that allots a full page to each species. Unfortunately, the resulting five-pound behemoth is not practical for use in the field. However, for birders interested in detailed descriptions of song, behavior, flight pattern, nests, and habitat, or who will be watching backyard birds from inside the house, this book offers more information than does a field guide.

Each full-page description begins by listing quick facts: common name, bird family, Latin name, length, and wingspan. Dominating the main panel is a large, color photograph of the bird, including a bullet-list of information pointing to specific distinguishing details (for example, on the female Common Eider, the "sloping profile" of the forehead is noted, distinguishing it from the female Mallard). Also included is another photograph of a female plumage, if different, and a small drawing of any juvenile plumages. For reference, the size of the bird compared to the book itself is shown in a silhouette.

The text description includes interesting information (did you know that the Great Cormorant carries water in its throat pouch to pour over its chicks when they get too hot?), plumage description and distinguishing characteristics, phonetic representation of the song, behavioral description, and breeding, nesting, and population information.

A very useful feature is the "similar birds" box, included on each page. This box lists birds whose ranges overlap that can be easily confused, shows a small picture of that bird, and indicates a few quick distinguishing characteristics. For example, the Rough-Legged Hawk is distinguished from the Red-Tailed Hawk by a "smaller bill and feet, feathered legs," etc.)

Small boxes highlight the bird's flight pattern, summer and winter range, and nest shape and location, with simple diagrams and detailed descriptions. The page ends with quick summary information about plumage variability between sexes, habitat (using icons so readers can see at a glance), migration patterns, and weight.

The introduction also offers an extensive look at identifying birds, including a detailed description of bird parts and behaviors, with many example photos. All notations and symbols used in the book are clearly explained here.

The two main drawbacks to the book are its size and its limited visual representation of various plumages. Though the book does include drawings of some alternate plumages, many more are omitted. Also, other field guides, including the National Geographic Field Guide to Birds of North America, often include a variety of plumages and behaviors, such as walking and flying, allowing easier identification. Therefore, it might be best to use this text hand-in-hand with a quality field guide.