A Mojave Rattlesnake from the Phoenix area. This brown and tan color is typical of this species in the area, though some of the more famously greenish ones do pop up as well. This one follows all the rules, with a clearly visible tail with bands of a roughly 2:1 white to black ratio, half yellow proximal rattle segment, and eye stripe extending beyond the corner of the mouth.

But what people who are very experienced use to identify a snake like this is not any of those features in particular. It’s the overall appearance, or gestalt. The “cleaner”, less speckled and chaotic pattern, slighter and more angular head shape, and outward appearance as a whole just hit as “mojave” in the mind upon sight. This isn’t to say, of course, that the features listed aren’t important, but all can be variable and fail an observer from time to time. It’s worthwhile, once a person has learned to identify these animals reliably based on details, to “zoom out” and look at the whole animal. Eventually, a Mojave Rattlesnake would stand out from similar-looking species in the same way you can likely tell the difference between a yellow lab and a retriever.