This book is a lot of fun. Each species gets its own page, where gobs of individuals are photo shopped into one collage that would be terrifying if it were a real scene. This book has improved my ability to ID birds from different vantage points. It provides frames of reference for size, and the real photos make it more realistic than Sibley’s guide. But it is heavy and doesn’t show up-close details as well as the Sibley Guide. For that reason, I usually leave Crossley in the car, and carry Sibley in my backpack.