This is the regal ringneck snake (
Diadophis punctatus regalis), a subspecies of ringneck snake endemic to the southwestern United States and northern Mexico.
Unlike other subspecies of ringneck snakes, the regal ringneck is almost exclusively ophiophagous, meaning that it has a diet that consists almost entirely of other snakes.
They have a weak venom that serves to immobilize their small prey, but is harmless to humans.
