SPIDERS AND THEIR KIN is a tiny treasure, a little book that will get you understanding and appreciating these incredibly important creatures, and even beginning to ID the major groups. Best $7ish ever spent.
PETERSON GUIDE TO WOODPECKERS: Learn from a longtime conservationist and woodpecker expert why most species are mainly black and white, and how they evolved to withstand all that hammering and much more, plus in-depth species profiles.
COMMON SPIDERS OF NORTH AMERICA: Want to get really serious about spiders? This is the book, richly illustrated and packed with learning: ID hints, native ranges, even behavioral insights into different species.
BETTER BIRDING: Not a field guide, exactly, but a serious guide to how the pros observe birds using contextual cues, from senior staffers of eBird.org and the American Birding Association. Particular focus on groups including raptors; sea, water and shorebirds; birds of the woodland edge; open-country birds, etc. Science-heavy.
COMMON LICHENS is an intimate look at these not-plants, not-animals that are essential to Earth’s health.
MAMMALS OF NORTH AMERICA: Who knew I lived alongside 52 species of mammals of America’s 462 total?
TRACKS AND SIGN OF INSECTS by Charley Eiseman demystifies all the lumps and bumps and squiggles and webs you see outdoors and ask, “What’s that?”
GARDEN INSECTS of North America (Princeton): Whitney Cranshaw’s comprehensive, easy-to-use reference is a gardener’s must-have tool.
KAUFMAN FIELD GUIDE TO BUTTERFLIES of North America: Probably the only butterfly book you’ll ever need, plus easy to use.
KAUFMAN GUIDE TO INSECTS, a perfect overall guide to representative insects of every major group, with biology and life histories.