The Crossbill guides offer a holistic experience to nature watching in the various destinations covered. A good third of each book is taken up by an introductory section that covers the history and geology of the regions as well as the flora and fauna. Then, the books move on to covering routes, which vary between a few hours of walking and a multi-day, multi-destination round trip. Most routes sit somewhere between these two extremes, taking between half and a full day and combining walking and driving.