As the title says: this is a natural history guide to the mammals of California. Most illustrations and range maps are black and white, though there are a handful of colored illustrations, in photographic plate pages at the center of the book. There is also a wonderful, introductory section that discusses the characteristics of mammals, in general — their basic behaviors, ecological niches, etc. However, unless you already know the order to which the animal you spotted belongs, you might have a hard time finding the information you need in this book. You’d really need a second field guide, in addition to this one, to help you find the information you need. But then, most field guides I have seen do not contain all of the mammals you are likely to spot in California, so it is still a necessary reference book for anyone engaged in nature study in the Coast Range Mountains of California.