A Heron on a mission and at a steady pace (that helps).
Cypress trees and last years nests are here. To a Great Blue there is no need to build when you can renovate. Like getting a ‘fixer upper’ house.
The experienced males have claimed the best spots, new birds will poke around and look for what they can find now.
It’s best the new comers keep away from the other established nests. That is when things get ugly.