Almost stepped on this one!

With camouflage perfectly suited to this region, the common Sonoran Gopher Snake can be found in the desert, in wooded areas, and in grassy areas also. If disturbed it's easy at first to mistake it for a rattlesnake ~ it will shake its tail and rise up and hiss loudly. I almost stepped on this one in a residential neighborhood. This photo has nothing to indicate scale but I estimate it was about 4' long.

Here's what the Desert Museum has to say about these snakes (also called Bullsnakes):
http://www.desertmuseum.org/books/nhsd_gopher_snake.php

And more info and a few more photos can be viewed here:
http://www.wildlifenorthamerica.com/Reptile/Sonoran-Gopher-Snake/Pituophis/catenifer-affinis.html