Unnamed spotting

Yes, interesting observations.

What I found interesting is that as opposed to the bigger, fatter (and less colorful) bull snakes I grew up with in the outskirts of Denver, this snake was completely unperturbed by my presence and didn't stop and present any aggressive rattlesnake mimicking. Thanks for you input!

Length and dark-light repeating squares dorsal pattern looks like Pituophis catenifer group to me. However considering range, then your spotting locale puts it in the range of the western subspecies (according to http://nmherpsociety.org/reptiles/snakes... ), Pituophis catenifer affinis, known as the Sonoran gopher snake. I suppose they also mimic rattlesnake behaviors (?) but perhaps there is individual/situational variability...Maybe wait and see if other users concur or chime in if you have reservations. :-)

Thanks! Do you think your ID is definitive? My recollection of Bull snakes in Colorado is that they were fatter and imitated a rattler when approached.