Hi,
I haven't read this book, but I know the authors. They are top-notch researchers, so I imagine this is a great book, on par with Rossman et al:
"North American Watersnakes" (Gibbons and Dorcas)
Welcome to the University of Oklahoma Press - home
It looks like you guys have the Thamnophis books covered. My favorite field guides for the US are the reliable Peterson's (east or west, depending on where you herp). A really good book is Harry Greene's "Snakes: The Evolution of Mystery in Nature". This is really well written (much more interesting than many science and textbooks) and full of information about all aspects of snake biology/ecology/behavior....
melissa