Loggerhead Shrike kill
A dozen or so of these large caterpillars were traveling rapidly across the ground in a dry gravelly wash. There had been recent rain, and many plants had greened up.
Definitely a heteromyid of some kind. I'm assuming Chaetodipus based on size. Looked like it was maybe ~180mm total length. They are EVERYWHERE but super fast and hard to photograph. They like these rock piles around electrical equipment.
ASM Tucson conference. Found outside of our air bnb in the driveway next to metal garage door.