Morning Robin, lucky to see - nice shots
In my experience, yes they seem to hang around the same trees and spaces - for a few weeks, maybe just a couple max - then they seem to disappear - they are susceptible to predators
If you go back the next day at about the same time …… in the afternoon ………you will usually see them and most of the time they take little notice of you
also you can usually see them in the same place year after year - I have only ever seen them in Jan/Feb
but as you say they NEVER keep still