The “U.S.-Mexican borderlands” extend within 100 miles from the international boundary and from the mouth of the Rio Grande to the western edge of the Sonoran Desert. This well-written book is a series of essays on the author’s observations and opinions from his 26 years of travel in this diverse region. The topics covered are diverse, too: vegetation types, birding near Brownsville, DDT and its effects, the “arch predator” (Homo sapiens), hummingbirds, “then-versus-now” photography, the coati, pupfishes, and many others. Gehlbach concentrates his efforts on animals, saying relatively little on plants.