This Great Blue Heron (let's call it A) was walking slowly in the ditch and onto the grass field.
When suddenly another Great Blue Heron (call it B) charged from a short distance away at the direction that A was walking towards to. Causing A to fly away in the opposite direction (also a short distance away).
Great Blue Heron B displaying its territorial display. According to the Pacific Wildlife Foundation, "Herons on adjacent territories display to one another by extending the wings away from the body, arching the neck, pointing the bill a few degrees above horizontals and erecting the feathers." Yep, I definitely saw that.