Crotalus Atrox, I presume…

I believe this patient, predatory observer of our sunset ambulation to be a Western Diamond-backed Rattlesnake.

According to the Arizona Game and Fish Department, this stealthy slitherer is responsible for more bites and deaths to mostly hairless bipeds than any other rattlesnake in the U.S.

The noisy end of this all-neck beasty is equipped with not only an auditory alarm, but also a high contrast, attention getting, visual advertisement, in the form of alternating light and dark stripes.

Interesting that such a sensor packed, all terrain, mammal seeking missile would benefit from an advertisement of its proximity…